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SSeelleennoollooggyy TTooddaayy iiss ddeevvootteedd ttoo tthhee ppuubblliiccaattiioonn ooff ccoonnttrriibbuuttiioonnss iinn tthhee ffiieelldd ooff lluunnaarr

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CCoonntteennttss

EEaarrllyy CCeennttrraall PPeeaakk vviissiibbiilliittyy iinn TTyycchhoo aanndd CCooppeerrnniiccuuss ccrraatteerrssby Maurice Collins ............................................................................................................. 4

LLuunnaarr ddoommeess AAttllaass oonn lliinnee ((GGLLRR ggrroouupp)) .................................................................. 9

PPuuttaattiivvee ccaallddeerraa bbeeiinngg tthhee ssoouurrccee ffoorr aatt lleeaasstt ssoommee ooff tthhee BBooddee ppyyrrooccllaassttiiccss ::ssppeeccttrraall ssttuuddiieessby Raffaello Lena Geologic Lunar Research (GLR) group ................................................ 19

LLuunnaarr SSoouutthh PPoolleeBy Rik Hill ............................................................................................................................ 27

LLuunnaarr eecclliippssee OOccttoobbeerr 88 22001144By Jim Phillips & Maurice Collins ...................................................................................... 28

TThhee SSttrroommbboolliiaann eerruuppttiioonn ssttyyllee aanndd tthhee vvoollccaanniicc eerruuppttiioonnss ffrroomm SSttrroommbboolliiBy Raffaello Lena Geologic Lunar Research (GLR) group ................................................ 31

PPaarrttiiaall SSoollaarr EEcclliippssee OOccttoobbeerr 2233,, 22001144By Mike Wirths and Pamela Weston ................................................................................. 44

LLuunnaarr ssoouutthh ppoollee wwiitthh ccrraatteerr NNeeuummaayyeerr aatt tthhee ppooiinntt ooff mmaaxxiimmuumm lliibbrraattiioonnBy Rik Hill .......................................................................................................................... 46

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TThhee NNeeccttaarriiss MMuullttii­­RRiinngg IImmppaacctt BBaassiinn:: FFoorrmmaattiioonn,, MMooddiiffiiccaattiioonn,, aannddRReeggiioonnaall GGeeoollooggyyby Richard H. Handy ....................................................................................................... 58

CCOOVVEERR

ccrraatteerrss CCooppeerrnniiccuuss&&

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bbyy MMiikkee WWiirrtthhss ((11)) && GGeeoorrggee TTaarrssoouuddiiss ((22))

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EEaarrllyy CCeennttrraall PPeeaakk vviissiibbiilliittyy iinn TTyycchhoo aanndd CCooppeerrnniiccuuss ccrraatteerrss

by Maurice Collins

I have been intrigued by spacecraft imagesshowing the interiors of craters lit only by the lightreflected of their lit crater rims and Earthshine. Iwondered if it would be possible to see this effectfrom Earth using only an average sized (20cm/8inch) SCT telescope, the largest aperture I possess,and a Zwo Optical ASI120MC colour imager camera.

There had been Transient Lunar Phenomena(TLP) reports by amateurs of central peaks ofcraters being visible before they should be lit bydirect sunlight. These TLP reports describeobservations of faintly lit interiors of craters withmisty glows, so it seemed a realistic exercise to tryto capture an image of this effect to see if it werereal and explainable.

On 2014 August 4 as I was imaging the 8 dayMoon for a full disk mosaic, where the sun was justrising on the rim of the great rayed crater Tycho inthe southern lunar highlands. Even though I did notset out planning to do this experiment that night, as Ididn't know Tycho was just at sunrise, when I sawTycho's lighting I thought this would be an ideal timeto try and see if the central peak was able to be seeninside the darkened shadow of the crater interior, soI attempted to try (Fig. 1).

I had taken normally exposed images momentsbefore at 09:15 UT at 0.006506 seconds exposure,where I could not see any central peak being lit bythe sun at this stage on the live image in theSharpCap software displayed on the screen of mylaptop connected to the C8 telescope. At 09:15 UT Itook two exposures at 0.037511 seconds, then at09:16 UT a longer one at 0.120403 secondsexposure.

At 09:17 UT I took another exposure of0.120403 seconds. All were taken using the samecamera, and I was able to see the central peakilluminated in the shadows by rim light, on screen,with each frame that downloaded!

I took a further exposure at 09:17 UT of0.16136 seconds, I also took another "after" shot at09:18 UT to show that it was not suddenly litnormally by a rising sun just at that moment using0.008705 seconds, and neither the "before" or"after" images show the central peak being lit yet.Later when visual observing at around 09:34UT Icould visually see the peak very faintly glowinginside the shadows of Tycho, lit only by the light ofthe brilliantly lit western rim reflecting light into theinterior, that sun had not yet risen on its peak. TonyCook did a calculation to show that the sun was atan angle of 1.6 degrees at the time of my image,which is confirmed by the Lunar TerminatorVisualization Tool. LTVT also confirmed that therewas no light reaching the central peak in the DigitalElevation Model (DEM) option used to draw thelunar surface at those lighting conditions (at solarangle from 1.6 degree to 1.9 degree) to confirm myobservations that the peak was only lit by rim lightnot direct light.

The following night, 2014 August 5, the sunwas just rising on the crater Copernicus, with itsinterior still in shadow. So I thought I would try tosee if the central peaks of Copernicus were visibleunder similar conditions as well (Fig. 2).

At 06:00UT after taking a full mosaic of theMoon, I trained the telescope (again my Celestron8"/20cm Schmitt­Cassegrain) on the crater andtook a long exposure. I exposed for 0.037511seconds for two images, one after the other. I reallywas not expecting to see anything, but in later

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processing the next morning several of the centralpeaks were visible! I made a montage of images takeat 06:00 UT long exposure 0.037511, 06:01 UT atnormal exposure of 0.006506 seconds, and onetaken later after the sun had risen more and waslighting the central peaks at 08:34 UT at normalexposure of 0.006506 seconds. I sent it off to ChuckWood at Lunar Photo of the Day, and he posted itthat afternoon Aug 6.

Dr. Wood was able to enhance the imagefurther and bring out the peaks much more clearlyand was able to describe three peaks being visibleby the light of the reflected crater rimshine. Bycomparing the long exposure with the later imagetaken at 08:34 UT where the peaks are illuminated, itis possible to match up the same peaks lit in the longexposure image.

Several days later I was reading in H.P.Wilkins "Our Moon" [1] and noted that Percy Wilkinshad also observed Copernicus's peaks and had thisto report :

"On March 29, 1939, the great crater of Copernicuswas finely displayed. The sun was rising there andthe shadows of the western wall were just beginningto creep down the slope of the opposite or easternwall. The whole of the interior was in shadow.Suddenly a faint glow appeared inside Copernicusand the group of little hills near the centre were seento be not sharply defined but rather as though theywere being viewed through fog. This lasted aboutfifteen minutes then vanished. It was not until fourhours later that the first ray of direct sunshinetouched the tops of the hills near the centre.Surprisingly, however, not only the tops but the wholeof the hills were seen at a time when it was notsunshine which revealed them. Where, then, did thelight come from?"

Though H.P. Wilkins did not figure it out, itappears to be sunlight reflected from the lit rim thathas lit up the interior and central peaks, however,why it would be visible for only 15 minutes thenvanish is slightly puzzling. My explanation for thiswould be that the light of the rim overwhelms the eye

in detecting the peak after a certain level, so itvanishes until it is lit directly by sunlight at localsunrise. However, TLP researchers have possibleother explanations, such as dust levitating orgaseous emission of some sort, making ittemporarily visible. Further research andobservations are needed to finally explain why itthe central peaks are sometimes visible, andsometimes not under similar lighting conditions.Perhaps I lucked out that night in capturing it at justthe right time? For more detailed information on theTLP's of central peaks, I refer you to the article inrecent October 2014 BAA lunar section Circular [2],and the ALPO October 2014 "The Lunar ObserverNewsletter" [3] by Dr. Tony Cook, who hasanalysed my observation in relation to TLPs of thepast, especially the excellent observation ofTycho's central peak by Brendan Shaw observedeven earlier than I detected it. Tony Cook's articlealso lists future watch times for similar lightingconditions at Tycho.

Please send any further observation to Dr. TonyCook at email: atc@aber.ac.uk or to the author atmauricejscollins@hotmail.com

EEddiittoorr nnoottee:: We invite all readers of SelenologyToday to send possible observations or ownarticles on the visibility of these central peaks alsoto the editorial board: gibbidomine@libero.it

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Fig. 1

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Fig. 2

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RReeffeerreenncceess::1. Wilkins, H. Percy (1954) Our Moon. Frederick Muller Ltd, London. page 1322. BAA LSC Oct 2014: http://www.baalunarsection.org.uk/2014­10­lsc.pdf (available soon)3. ALPO TLO Oct 2014: http://moon.scopesandscapes.com/tlo_back/tlo201410.pdf

TTaabbllee 11:: the table displays the repeat illuminations of Tycho.

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LLuunnaarr ddoommeess AAttllaass oonn lliinnee ((GGLLRR ggrroouupp))

Lunar domes are structures of volcanicorigin which are usually difficult to observe dueto their low heights.Different methods for determining themorphometric properties of lunar domes(diameter, height, flank slope, edifice volume)from image data or orbital topographic data, andfor determining multispectral images dataproviding insights into the composition of thedome material, have been examined anddiscussed in the book published by SpringerLunar Domes: Properties and FormationProcesses. Furthermore, the book we havepublished provides a description of geophysicalmodels of lunar domes, which yield informationabout the properties of the lava from which theyformed and the depth of the magma sourceregions below the lunar surface.

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Lunar domes represent a clear testimonyof the volcanic processes occurred in our Moon.In fact, the differences in dome shapes andrheologic parameters raise broad questionsconcerning the source regions of the variousdome types allowing the knowledge of whichdifferences in the lunar interior are responsible forthe different lunar dome properties observed onthe surface.The book Lunar Domes: Properties andFormation Processes is a reference work onthese elusive features, providing the methodsused to study quantitatively these volcanicconstructs.

The purpose of the present Lunar dome Atlas,complementary to the book, is an uniformcollection of CCD terrestrial images for eachdome including really high resolution imagery withthe scope of a presentation of all the dome fieldsinformation, including tables describing theirproperties in terms of morphological measu­

rements and rheologic properties.

Lunar domes with their typically low flankslopes display a significant contrast with respectto the surrounding surface only when the solarelevation angle is lower than 4–5°. For thisreason, as illustrated in the Lunar dome Atlas, itis necessary to image these volcanic edificesunder strongly oblique illumination condition. Onlyslightly different solar elevation angles may resultin strong differences in the appearance andvisibility of the lunar domes and their shadow.High resolution CCD imagery of the elusive lunardomes is the most difficult branch of theastrophotography of the Moon. Notably, thedetailed study of lunar domes is only possiblebased on images of the lunar surface acquiredunder strongly oblique illumination conditions, fortheir measurements and for the maximum detail.The recording of finer details will be obtained withtelescopes optically of high quality, largediameter, and favorable observing sites in orderto reduce the effect of the atmosphericturbulence.

The domes atlas is on line athttp://lunardomeatlas.blogspot.it/

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Raffaello Lena was born on 2 September 1959.He has published lunar articles in Icarus,Planetary Space Science, LPSC conferences,JALPO, Selenology, JBAA other than inAmerican and Italian magazines. Over the lastdecade the Geologic Lunar Research Groupthat he founded has produced dozens ofpublished studies of lunar domes, faults andtransient phenomena. He has been interestedin the Moon since he was 10 years old and hasprogressed from a small Newtonian telescopeto high quality scopes (6” Maksutov Cassegrainand a 5” refractor). His first interest in lunarstudies is represented by the lunar domesanalysis and their classification. He is thecoauthor of the book Lunar domes propertiesand mode of formation published by Springer.He works also on interpretation of TLP and hasdeveloped procedures for interpretation of alunar flash in order to identify if it is of real

impact nature. He has been the first Italian todocument a lunar impact because it wassimultaneously recorded also in Switzerland fromother two observing sites (independent andsimultaneous observation with a distance of theobservatories > 500 km). Whenever possible helistens to jazz and explores Italy’s volcanoes andmountainous geology.

He has a doctorate in pharmaceutical sciencesfrom the University of Rome and currently works onfood safety.

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Maria Teresa Chiocchetta She has published articles in the field oflunar studies and participates in the activity of the Geologic LunarResearch Group. She is the coauthor of the book Lunar domesproperties and mode of formation published by Springer. She isinterested in the Moon since she was 10 years old and hasprogressed from a 8” Schmidt Cassegrain to a 10” MaksutovCassegrain. She lives in Sestri Levante Genova Italy and work in thefield of construction engineering.

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Michael Wirths My interest in Astronomystarted in my early teens when I saved upenough money from mowing my Parents andneigbors lawns to buy a cheap $25 Tascorefractor. Subsequent ownership of otherscopes such as driven C­8's and 6" Newts onheavy German equatorial mounts created asense of frustration in me as I had nobody toguide me in my hobby, but that all changedwhen I joined the Ottawa Royal AstronomicalSociety of Canada. Through that club and itsactivities I was able to realize that therelatively low tech driven dobsonian was thepath for me. My later to be observing partnerand friend Attilla Danko gave me my first everview through a large dobsonian telescope andI was amazed how much detail and colourcould be seen when the seeing allowed, evenbetter than the F­12 superplanetary 5"Astrophysics refractor that I was fortunate toown for a year. Later my experience at thefamed Texas Star Party led me to the gotodriven Starmasters and the sublime efforts ofthe master optician Carl Zambuto, thesescopes are what I currently observe andimage with, specifically a 45 cm (18")Starmaster. Of course during all that time myWife Pamela Weston and I had been runningan equestrian centre for well over a decade

but both of us were tiring of the harsh cold Ontario winters but a lucky series of small vacations innorthern Baja California Mexico gave us the opportunity to purchase a 500 hectare (1200 acre) piece ofland on the periphery of the Sierra San Pedro Martir national park. This area is highly desirable forastronomy due to its clear weather and above average seeing conditions. So it came to pass that we soldeverything we had in Canada to start a new adventure with an astro B&B and we are going into our 6thyear here in the high Sierra. The last 8 years of my life I have surprisingly been drawn to high resolutionlunar/planetary imaging, even though I never had any desire to do so before since I was stricly a visualobserver. My involvment with the GLR and LPOD was of course a natural progression since like mindedindividuals seem to find each other no matter what geographic distance seperates them! Together we aretrying to push the boundaries of what is possible for amatuers to achieve, who knows where this path willtake us!

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Paolo Lazzarotti I was born in 1973 in Massa, Tuscany, andI started my passion with Astronomy in 1995 when thebeatiful Hale­Bopp comet appeared in the sky and caught myattention. Hence, I observed and imaged anything crossingthe sky but the light pollution here narrowed my interest inthe planetary field only. My interest with Planets and theMoon grown up quickly over years and now I even built bymyself a dedicated instrument for the hires study of the SolarSystem, including the Moon. I'm contributor with GLR groupsince many years and co­author with lots of their lunarresearches and lunar articles.

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James Phillips has been interested in Astronomy for most ofhis life. He lives in South Carolina, USA. He was luckyenough to have a Mom who knew of his interest inastronomy and his desire to have his own telescope. Thatwas enough for Jim. While wanting to observe as manythings as possible with my telescopes, the Moon, planetsand double stars became my primary objects of interest.His telescopes grew as did his interest in amateurastronomy. In next years he was able to buy an R.E. Brandtachromatic doublet which was made into a telescope usingirrigation pipe by Tom Dobbins. He had read about LunarDomes by Patrick Moore (of course). Jim tried to join theALPO lunar Dome program but found it no longer existed. Atthe suggestion of John Westfall the head of ALPO at thetime, he started the New Lunar Dome Survey of the ALPO.This lasted for several years ending up with a catalog oflunar domes. It was not a complete list nor nearly asaccurate as he had hoped but it was a start. About this timeJim started corresponding with Raffaello Lena the founder ofthe GLR (Geologic Lunar Research group), which wanted tocontinue the work on Lunar Domes to complete an accuratecatalog, establishing a lasting friendship. He is interested inthe GLR because the observers are so friendly and there isreal work going on that I can contribute to. He is the

coauthor of the book Lunar domesproperties and mode of formationpublished by Springer. Today He observeand image with an AP 10" F/14.6Maksutov­Cassegrain and an APM/TMB10" F/9 apochromatic refractor with LZOStriplet lens, and uses Skynyx cameras plusRegistax and Photoshop for processing.

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Carmelo Zannelli I was born on 29 April 1967 in Palermo, Sicilyand I started my passion with Astronomy in 1977 when I was10 years old. My first telescope was a small telescope ofdiameter 50 mm followed by a Newtonian 114 mm. Subsequentownership of other scopes such as a Newtonian 130 mm, aMaksutov Newton 180 mm, a Celestron C­9,1/4, a CelestronC­11. Actually my telescope is a Celestron C­14 starbright.Between the years 1980 and 1990, with my friend GiorgioPuglia, I started with to image the deep­sky obtaining severalawards in national competitions. I am graduated in PoliticalSciences at the University of Palermo. I am a founding memberof the O.R.S.A. (Organizzazione Ricerche e Studi diAstronomia) in Palermo, association founded in 1984, and workfor GLR group since many years. Today I use a camera PointGrey Flea3 for planetary imagery and a camera BaslerACE1300gm to image the Moon, both monochrome. The filtersused are the Baader LRGB, placed in a motorized filter wheel.

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Stefan Buda I was born in 1958 in the Eastern Blocand I had a fascination with technology from the earliestage. When Apollo 8 flew around the Moon I wascaptivated by the news on the radio and never stoppedfollowing space news ever since. In my early teens Ifound an old booklet, in a dusty attic, that started with avivid description of Schiaparelli observing the planetMars and discovering "canali", then the story moved onto Lowell and all the speculation about life on Mars. Iwas enthralled! It did not take long before I was able tosee craters on the Moon with a telescope I made froman uncut ophthalmic lens, a cardboard tube and a smallmagnifier. After finishing my formal education inmechanical engineering and completing my compulsorymilitary service, at the age of 23, I put my life on the lineand escaped across the Iron Curtain to the West. A fewmonths later I found freedom in Melbourne, Australiawhere I've been living since. I ground my first telescopemirror in 1985, in time to observe Halley's comet with it.That was followed by many other telescopes andastrographs of increasing complexity. In the late 1990s Istarted experimenting with electronic imaging of theplanets, first with video and then with home made CCDcameras and finally moving onto webcams. My targetswere mainly the planets Mars, Jupiter and Saturn.

The Moon became interesting again forme more recently when I realized that thelatest generation of frame stacking softwarecan do an amazingly good job of unscramblingatmospheric distortions.

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George Tarsoudis He was born on 7 November 1970 atthe Basel (Switzerland). Since 1978 he lives inAlexandroupolis (Greece).He started passion with Astronomy in 2004 and he wasone of the founding members of the Thrace AmateurAstronomy Club (TAAC).He is a Lunar and Planetary observer and now he has aSkywatcher Telescope BK DOB14" Collapsible 355mm@f/4.5. His recent images are at the link of his website:

http://www.lunar­captures.com//Skywatcher_14inch.html

He has 69 Lunar Photo of the day (LPOD) and somepublications at Magazines & Books. Moreover some hisimages are included in "The Astronomy Photographer ofthe Year book" from the Royal Observatory Greenwich.He works for Selenology Today Journal of GLR group(as publisher and editor) and has done some lectures fordissemination of astronomy to the general public.

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PPuuttaattiivvee ccaallddeerraa bbeeiinngg tthhee ssoouurrccee ffoorr aatt lleeaasstt ssoommee oofftthhee BBooddee ppyyrrooccllaassttiiccss:: ssppeeccttrraall ssttuuddiieess

By Raffaello Lena Geologic Lunar Research (GLR) group

IInnttrroodduuccttiioonn

In the LPOD dated July 25, 2014, C. Woodspeculates the presence a volcanic caldera, one of thelargest on the Moon. In fact dark deposits extend awayfrom the rim of a crater, consistent with the putativecaldera being the source for at least some of the Bodepyroclastics. A spectral study of the mentioneddeposits, according to the methods used by GLRgroup, was performed. In this work are described theresults obtained using the Clementine and M3

multispectral data. The lunar pyroclastic deposit (LPD)described in this work belongs to the black beads.

MMeetthhooddssSpectral analyses are released on the

calibrated and normalized Clementine UVVIS and NIRreflectance data as provided by Eliason et al. (1999).The dark material extends beyond the crater rimsuggesting an ash type deposit (Fig. 1) and displays ablue color with a compositional contrast between theLPD and the mare based on the UVVIS ratios imagery(Fig. 2). To estimate the abundances of six keyelements, Wöhler et al. (2011) rely on the regression­based approach which involves the analysis of themafic absorption trough around 1000nm present innearly all lunar spectra. The continuum slope, thetrough width, and the centre wavelengths and relativedepths of the individual absorption minima occurring init are extracted from Clementine UVVIS–NIRmultispectral image mosaics. These spectral featuresallow on estimate of the abundances of the elementsCa, Al, Fe, Mg, Ti, and O based on a second­orderpolynomial regression approach, using the directlymeasured LP GRS abundance data as “ground truth”(Wöhler et al., 2011). The Titanium content computedwith the regression method based on Clementine datais inaccurate for “blue mare” soils, so that the TiO2 andFeO estimation equations by Lucey et al. (2000) may

be applied (shown in Figs. 7­8).Chandryann­1’s Moon Mineralogy Mapper (M3) isan imaging reflectance spectrometer that candetect 85 channels between 460 nm and 3000nm, and has a spatial resolution of 140 m and280 m per pixel. For this work M3 data, at aresolution of 140 mpp, were calibrated andphotometrically corrected and converted toapparent reflectance. Data have been obtainedthrough the M3 calibration pipeline to producereflectance with photometric and geometriccorrections. For deriving the spectral parametersthe photometrically corrected Level 2 data of thePDS imaging node have been used (Isaacson etal., 2011). The calibration of M3 data is presentedin detail by Green et al. (2011).These spectra are not thermally corrected, so wedo not analyze wavelengths longer than 2500 nmas these have a significant thermal emissioncomponent. This does not diminish the efficacyof the analysis because the relevant spectralfeatures are located below 2300 nm. In order tocharacterize the 1000 nm band, it was used acontinuum removal method that enhances thecharacteristic of the 1000 nm absorption bandand more accurately shows the position of theband center. So a straight line between 750 nmand 1500 nm to remove the continuum wasused.The Christiansen Feature (CF) fromGridded datarecord (GDR) level 3 data product of DivinerLunar Radiometer Experiment / LunarReconnaissance Orbiter (DLRE/LRO) data wereused for further analysis. The LunarReconnaissance Orbiter’s (LRO) Diviner LunarRadiometer Experiment has a spatial resolutionof 950m/pixel. Diviner produces thermalemissivity data, and can provide compositionalinformation from 3 wavelengths centered around8μm that are used to characterize the

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Christiansen Feature (CF), which isdirectly sensitive to silicate mineralogy andthe bulk SiO2 content (Greenhagen et al.,2010).

RReessuullttss aanndd ddiissccuussssiioonnThe pyroclastic deposit has a

R415/R750 ratio of 0.6445 and a R950/R750

ratio of 1.0787 (Figs. 2­3). Albedo at 750nm is an indicator of variations in soilcomposition, maturity, particle size, andviewing geometry. The R415/R750 colourratio essentially is a measure for the TiO2

content of mature basaltic soils, wherehigh R415/R750 ratios correspond to highTiO2 content and viceversa. The R950/R750

colour ratio is related to the strength of themafic absorption band, representing ameasure for the FeO content of the soil,and is also sensitive to the optical maturityof mare and highland materials

FFiigguurree 11

FFiigguurree 22.. RR441155//RR775500 rraattiioo FFiigguurree 33.. RR995500//RR775500 rraattiioo

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The color ratio image is obtained assigning theR750/R415, R750/R950 and R415/R750 into the red,green, and blue channels of a color image,respectively. The lunar highlands are depicted inred (old) and blue (younger). In the color ratioimage the maria are depicted in yellow/orange(iron­rich, lower titanium) or blue (iron­rich, highertitanium). The pyroclastic deposit is characterizedby a different color respect to the nearby soil andappears blue indicating an increased TiO2 content(Fig. 4).

The petrographic map is constructed interms of three different mare basalt end­members,where the relative content of mare basalt, Mg­richrock, and FAN is denoted by the red, green, andblue channel, respectively (Fig. 5). The highlandsoils stand out clearly as anorthositic highlandmaterial (blue). Basaltic mare plains and lava­filledcraters appear red orange while in the green areshowed Mg­rich rock, e.g. with high olivinecomponent.

Another petrographic map, termedpetrographic basalt map (Fig. 6), was thenrepresented as relative fractions of the three end­members: red for mare basalt with low Titaniumamounts (Al 9 wt%, Ti 1.5 wt%), green forhighland­like material (Al 14 wt%, Ti 0.5 wt%) andblue for titanium rich basalt (Al 6.3 wt%, Ti 3.6wt%).

FFiigguurree 44.. CClleemmeennttiinnee ccoolloorr rraattiioo iimmaaggee

FFiigguurree 55.. PPeettrrooggrraapphhiicc mmaapp ccoonnssttrruucctteedd iinn tteerrmmss oofftthhrreeee ddiiffffeerreenntt mmaarree bbaassaalltt eenndd­­mmeemmbbeerrss

FFiigguurree 66.. PPeettrrooggrraapphhiicc bbaassaalltt mmaapp

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In this map regions appearing in green are composedof highland material (or sometime mare basaltcontaminated with highland material by lateral mixingeffects). The LPD displays a titanium rich composition,according to the Clementine color ratio map (Fig. 2),while the eastern soils are of highland composition. Itis important to note that the derived amounts of Ti andFe might not be appropriate for some deposits due tothe possible presence of high amounts of glasses andother unknown factors. However the analysis,according to the Clementine color ratio imagesdisplaying a blue color with a compositional contrast,indicate that the “relatively” higher TiO2 and FeOvalues (Figs. 7­8) are associated with the pyroclasticdeposit if compared to nearby mare soil, which isreddish in the color ratio.

FFiigguurree 77.. TTiiOO22 ccoonntteenntt ((%% wwtt))

FFiigguurree 88.. FFeeOO ccoonntteenntt ((%% wwtt))

Spectral diagrams of the examined deposit(Fig. 9) indicate a composition similar to the blackbeads: mare soils are represented by the darkgrey regions and highland soils by the light greyregions, according to Gaddis et al. (2003).Taurus–Littrow, Sinus Aestuum, Vaporum, andRima Bode LPDs are all “blue” in Clementine colorratios and are known or inferred to have asignificant component of high­titanium materials (inthe form of ilmenite­rich black beads).

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FFiigguurree 99

The spectral signature of olivine has a wideband centered beyond 1000 nm, while thepyroxenes displays a narrow trough around1000 nm, with a minimum wavelength below1000 nm, and a wide absorption band around2000 nm. Chandryann­1’s Moon MineralogyMapper (M3) and Clementine data the spectra ofthe deposits would indicate a mixture of someolivine content and pyroxene (see Figs 10­12).

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FFiigguurree 1100

FFiigguurree 1111FFiigguurree 1122

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FFiigguurree 1133

The Christiansen Feature (CF) fromGridded data record (GDR) level 3 dataproduct of Diviner Lunar RadiometerExperiment/Lunar Reconnaissance Orbiter(DLRE/LRO) indicate values towards longerwavelength (CF ~8.55 micron) indicatingless silicic composition and at least in someparts with an olivine component (Fig. 13).

In conclusion the spectral studies indicatethat the dark deposit has a compositioncorresponding to the LPDs termed as blackbeads.

RReeffeerreenncceess

1) Eliason, E., Isbell, C., Lee, E., Becker, T., Gaddis, L., McEwen, A., Robinson, M.: Mission to theMoon: the Clementine UVVIS Global Mosaic. PDS Volumes USANASA PDS CL 4001 4078.http://pdsmaps.wr.usgs.gov (1999).

2) Gaddis, L.R., Staid, M.I., Tyburczy, J.A., Hawke, B.R., Petro, N.E., 2003. Compositional analysesof lunar pyroclastic deposits. Icarus 161, 262–280.

3) Green, R.O., Pieters, C.M.,Mouroulis, P., Eastwood,M., Boardman, J., Glavich, T., Isaacson, P.J.,Annadurai, M., Besse, S., Barr, D., Buratti, B.J., Cate, D., Chatterjee, A., Clark, R., Cheek, L.,Combe, J.P., Dhingra, D., Essandoh, V., Geier, S., Goswami, J.N., Green, R., Haemmerle, V., HeadJ.W., Hovland, L., Hyman, S., Klima, R.L., Koch, T., Kramer, G.Y., Kumar, A.S.K., Lee, K., Lundeen,S., Malaret, E.,McCord, T.B.,McLaughlin, S.,Mustard, J.F., Nettles, J.W., Petro,N.E., Plourde, K.,Racho, C., Rodriquez, J., Runyon, C., Sellar, G., Smith, C., Sobel, H., Staid, M.I., Sunshine, J.M.,Taylor, L.A., Thaisen, K., Tompkins, S., Tseng, H., Vane, G., Varanasi, P., White, M.,Wilson, D.,2011. TheMoonMineralogy Mapper (M3) imaging spectrometer for lunar science: instrumentdescription, calibration, on­orbit measurements, science data calibration and on­orbit validation. J.Geophys. Res. 116, E00G19, http://dx.doi.org/10.1029/2011JE003797.

4) Greenhagen, B.T., Lucey, P.G., Wyatt, M.B., Glotch, T.D., Allen, C.C., Arnold, J.A., Bandfield,J.L., Bowles, N.E., Donaldson Hanna, K.L., Hayne, P.O., Song, E., Thomas, I.R., Paige, D.A., 2010.

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Global silicate mineralogy of the Moon from the Diviner Lunar Radiometer. Science 329,1507–1509, http://dx.doi.org/10.1126/science.1192196.

5) Isaacson, P., Besse, S., Petro, N., Nettles, J., and the M3 Team: M3 Data Tutorial November2011 http://pds­imaging.jpl.nasa.gov/documentation/Isaacson_M3_Workshop_Final.pdf .

6) Lena, R., Wöhler, C., Phillips, J., Chiocchetta, M.T., 2013. Lunar domes: Properties andFormation Processes, Springer Praxis Books.

7) Lucey, P.G., Blewett, D.T., Jolliff, B.L., 2000. Lunar iron and titanium abundance algorithmsbased on final processing of Clementine ultraviolet­visible images. J. Geophys. Res. 105 (E8), 305(20,297–20).

8) Wöhler, C., Berezhnoy, A., Evans, R., 2011. Estimation of elemental abundances of the lunarRegolith using clementine UVVIS­NIR data. Planet. Space Sci. 59 (1), 92–110.

9) Wood, C. http://lpod.wikispaces.com/July+25%2C+2014

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LLuunnaarr SSoouutthh PPoolleeBy Rik Hill

On October 4­5 the libration of the moon was favorable for observation of the lunar south pole. Ienjoy peeking over the edge, so to speak, and seeing features that are only occasionally visible. I've markedsome of these transient features. Note on the far left the position of the Lunar Prospector Crash on July 31,1999. I observed that event with Dr. Ann Sprague on the 61" Kuiper Telescope (Catalina Telescope) on Mt.Bigelow in the Catalina Mountains north of Tucson. We had a large echelle spectrograph on the telescopewith the slit oriented perpendicular to the limb in hopes of seeing dust, enhanced continuum or maybe evenemission lines from vaporization, though this latter was very unlikely since the velocity of the impact was tooslow. In the end we saw nothing that we could attribute to the impact, but the set up and anticipation wasgreat fun.

North of Scott you can see two large craters, Schomberger and Simpelius and further on near the topof the image is Curtius. Above Demonax are also two large craters, Boguslawsky and Manzinus. Over nearthe right edge of the image is the great 134km diameter crater Boussingault and above it is Mutus with thetwo smaller (17 and 24 km) craters on opposite walls. Over on the left edge just barely seen is thelandmark 117km diameter crater Moretus.

The 2 images that made this montage, each made from 500/3000 AVI frames, were stacked usingRegistax 6, knit together with AutoStitch and final processing done with GIMP and IrfanView.

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LLuunnaarr eecclliippssee OOccttoobbeerr 88 22001144

I wish I had my small telescope (80mmLOMO F/6) with me but I did what I couldusing a Nikkor 70­200 F/2.8 lens with myNikon D810.

NIKON D810NIKKOR LENS 200MM @ F/2.8ISO Various

Here are a few images from the start ofthe eclipse and at/near totality with theBlood Moon appearance or, if squeamisha copper penny color.

By Jim Phillips

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BByy MMaauurriiccee CCoolllliinnss

The view throughbinoculars was nice, not sonice through my little ETXwhich couldn't grabmuch feeble light. I triedsome afocal shots through itwith a 32mm eyepiece at11:53pm which I have madeinto a montage (they are a bitblurred). It was quite dark,and not easily seen in theETX but there was thinclouds most of the time, but itlooked ok in binoculars andnaked eye. Not sure whatDanjon I would rate it, I agreewith the estimates I've seenso far of 2 or 3.

Not as good as the lasteclipse from here where itwas nice and clear until aftermid­eclipse. This time round Ikept taking the ETX backinside when it clouded overas couldn't tell if it was goingto rain or not. I gave uparound 12:30pm where itlooked pretty solid cloud.

Anyway, least we saw it andit was nice!

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TThhee SSttrroommbboolliiaann eerruuppttiioonn ssttyyllee aanndd tthhee vvoollccaanniicc eerruuppttiioonnss ffrroommSSttrroommbboollii

By Raffaello Lena Geologic Lunar Research (GLR) group

AAbbssttrraacctt

In this paper is described the Strombolian activity, including an overview of the Italian volcanoStromboli. The images of the volcano, and its eruptions, are taken by the Author. Some samples ofvolcanic rocks, from the private collection of the Author, are presented and described. A comparisonwith lunar strombolian eruption is given.

IInnttrroodduuccttiioonn

Volcanic eruptions created lava flows,pyroclastic deposits, pits, and domes on the Moon.The same process continues to operate on Earth,most reliably visible at Stromboli volcano which haserupted for more than a millennium (Wood, 2008; seealso Alean and Fulle, stromboli online). Some of thelunar pyroclastic deposits on the moon have beendescribed and modelled as compatible with aStrombolian or Vulcanian style of eruption.

GGeenneerraall oovveerrvviieeww

More than 100 lunar pyroclastic deposits havebeen recognized and classified as small and regionaldeposits on the basis of size and morphology(Gaddis et al, 2003 and references therein).Characterization of the nature of the lunar pyroclasticdeposits (LPDs) is essential for models of formation,segregation and emplacement of lunar magmas.There are two styles of volcanism that might leavedark mantling units on the moon. Regional depositsare thought to have been emplaced as products ofcontinuous or Strombolian­style eruptions, with widedispersion of well­sorted pyroclasts (Gaddis et al,2003; ). Intermittent or Vulcanian­style eruptionslikely have produced the small pyroclastic deposits,with explosive removal of a plug of lava within a

conduit and forming an endogenic vent (Head andWilson, 1979; Weitz et al, 1998).Thus the Strombolian eruptions may have formedthe largest dark mantle deposits on the moonwhile the Vulcanian eruptions feature shortexplosions of gas and rocks and tend to besmaller than Strombolian eruptions. Becausegases need to build up near the vent, they do notinvolve large volumes of magma. Hence,Vulcanian eruptions likely form the smallerpatches of dark materials on the moon, with arecognizable central pit or vent structure (Headand Wilson, 1979).Among the largest of the dark mantle deposits areAristarchus plateau, Mare Humorum, South MareVaporum and Sulpicius Gallus deposits.On the Earth continuous Strombolian explosions,sometimes accompanied by lava flows, have beenrecorded at Stromboli (Italy) for more than amillennium.

Stromboli, the North East of the AeolianIslands, is the emergent summit of a volcano thatgrew in several eruptive periods, the last of whichformed the western portion of the island (Fig.1a).Ginostra, located to the West, is likely thesmallest port in the world (Fig 1b). About 200000years ago, Stromboli had not yet reached sealevel but another volcano, called Strombolicchio,was active. Today Strombolicchio is an erodedvolcanic neck of basaltic andesitic composition(Fig.2).

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FFiigguurree 11aa::map of Stromboli

FFiigguurree 11bb::Ginostra village (imageby the author)

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The geologic evolution of Stromboli volcano isrecorded in its subaerial part and four major periods(Paleostromboli, Vancori cicles, Neostromboli, RecentStromboli) have been recognized and furthersubdivided in 30 volcanostratigraphic units (Fig.3).These main divisions are defined largely by collapseepisodes of the volcanic edifice (Fig. 3). The Vancoriproducts filled the remnants of the Paleostromboliedifice, a caldera formed at the end of thePaleostromboli period (Hornig­Kjarsgaard et al.,1993). A lateral collapse defines the end of theVancori period and the Neostromboli collapse, whichoccurred in the same direction, defines the end of theNeostromboli period (Hornig­Kjarsgaard et al., 1993;Tibaldi et al., 1994; International Geoscience programand references therein). Subsequently, a new ventbecame active in the area of Pizzo sopra la Fossa(Fig. 1), marking the onset of the recent activity of thevolcano. Several smaller collapses have occurred inthe same area, forming the Sciara del Fuoco in itspresent shape and resulting in a highly faultedvolcanic edifice. The Sciara del Fuoco formed about5000 years ago (cf. Fig.4). During the first two periodspyroclastites (ignimbrites, surge and lahar deposits)predominate over lavas. The more recent products are

generally basalts and andesites spanning the complete range of subduction­related magma series fromcalc­alkaline to shoshonitic. The activity of the Vancori and Recent periods is shoshonitic, whereas theNeostromboli period products are richer in potassium (Francalanci et al., 1989).

In locality Piscità (Fig.1) a lava tube is visible, which formed after the surface of a lava flow cooledand solidified, developing a continous crust beneath which the still molten interior lava continued to flowtoward the sea. The active vents are well visible from the Sciara del Fuoco or from the highest peak of thevolcano Pizzo sopra la fossa (cfr. Figs 1 and 3). The slope below the vents is covered with debris from theOctober 1993 explosions. Interestingly some small yellowish patches between dark ash located near thecrater 1 are apparent. They are remains of Neostromboli volcano, which have been chemically altered bycorrosive action of the fumaroles, still visible in the upper portion of the cone. Figs. 1­10 provide thestratigraphic relationship and the different volcanic products that can be observed today in Stromboli. All theimages were taken by the Author.

FFiigguurree 22::Strombolicchio an eroded volcanic neck(image by the author)

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FFiigguurree 33::

Geologic map of Stromboli;1, eruptive fissure; 2, craterrim; 3, flank and sectorcollapses; 4, summit caldera;5, dike; 6, young parasiticvent; 7, active vent; 8, oldestrock units comprisingPaleostromboli I, II e III; 9,Vancori series; 10,Neostromboli rocks; in whiteare the Recent Perioddeposits (from Pasquarè etal, 1993).

FFiigguurree 44 :: periods of volcanism and collapse in Stromboli

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FFiigguurree 55 aa..

Basalts and scoria from thePaleostromboli volcano (image by theauthor)

EErruuppttiioonn ssttyyllee aanndd MMiinneerraallooggiicccchhaarraacctteerriissttiiccss

The magmas of the Aeolian islandsare similar to those of volcanoes that makeup the "belt of fire" in Pacific ocean. Theyshow, over time, the trend towards evermore basic compositions (lower content ofsilica) and more rich in potassium. Thesample shown in Fig. 11 is an andesite withreddish hue and vescicular texture. Themain phenocrysts are plagioclase feldsparand with the presence of pyroxene(clinopyroxene) and olivine. For a detailedaccount of the mineral chemistry ofStrombolian basalts refer to Francalanci etal (1989) and Wilson et al (2006). HoweverStrombolian eruptions normally occurseveral times per hour from one or more ofthe active vents sited 150 m below thePizzo Sopra la Fossa (Fig. 1). Theseexplosions led to fallout of fresh lapilli orscoria. Samples of lapilli and scoria (seeFig. 12) collected on Stromboli belong tothe black scoriaceous volcanic materialnormally erupted during Strombolianactivity.Figure 12 shows a vesicular, blackin color, glassy rock formed during

eruptions, when decreasing pressure causes gas to «bubble out» of andesitic and basaltic magma. Theblack color is mostly due to its iron content. As shown from volcanic material and petrologic analysis, theactivity in Stromboli and nearby Vulcano island, is different from the material produced during the volcanicactivity in the Lipari island, another Aeolian island, which contains craters and lava domes on a basement ofsubmarine volcanic deposits. The latest eruption in historic times, probably in 729 AD, at Monte Pilatus at theNE tip of the Lipari island, formed obsidian lava flow and deposit of pumice (cfr. Figs. 13 and 14).

Stromboli has an activity characterized by the intermittent explosion or fountaining of lava from thevents, especially from crater 1 (the NE­crater) and crater 3 (the SW­crater), with scoria, lapilli and ashejected within a very restricted area close to the vents (Fig. 15). Occasionally the volcano enters a period ofmore activity called a ‘paroxysm’. This is characterized by the ejection of the volcanic products outside thecaldera rim and bombs can even land on the villages on the island. Bertagnini et al.(1999) reported emissionof “golden pumice” when associated with paroxysmal explosive events.

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The magma in a Strombolian eruption rises slowly in the vent, allowing bubbles to coalesce andseparate from the melt, as they rise to the top of the magma column. Upon reaching the surface, the gaspocket disrupts the magma, throwing it out ballistically. The whole cycle repeats, with individual blastsseparated by anything from a fraction of a second to hours (Fig. 16).Two main possibilities have been proposed to explain the paroxysmal explosive events: changes in thevolatile flux, or changes in the groundwater level. Recently it has been demonstrated that paroxysm isheralded by anomalous increases in sulphur degassing (Aiuppa & Federico, 2004) and CO2 and H2

degassing (Carapezza et al., 2004), strongly suggesting that the shift in the style of activity is mainlycontrolled by changes in the volatile flux.

FFiigguurree 55bb.. Basalts and scoria from the Paleostromboli volcano (image by the author)

LLuunnaarr PPyyrrooccllaassttiicc mmaatteerriiaall

The explosive eruptions that formed the lunar dark mantle deposits have been likened to sometypes of terrestrial volcanic activity. Intermittently explosive or Vulcanian­style eruptions are likely to haveproduced the small pyroclastic deposits, with explosive decompression acting to remove a plug of lavawithin a conduit and to form an endogenic vent crater (Head and Wilson, 1979). The small pyroclasticdeposits have been further subdivided into three compositional classes on the basis of their "1.0­micron"or mafic absorption bands in Earth­based spectra (e.g., Gaddis et al and references therein , 2003). Maficbands of small pyroclastic deposits in the Group 1 class are centered near 0.93 to 0.95 microns, havedepths of 4 to 5%, and are asymmetrical,. Their spectra resemble those of typical highlands and are

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indicative of the presence of feldspar­bearing maficassemblages which are dominated by orthopyroxene(e.g . small pyroclastic deposits are found on thefloors of Atlas Crater). Mafic bands in spectra forGroup 2 deposits are centered near 0.96 microns,have depths of ~7%, and are symmetrical in shape.Group 2 spectra are similar to those of mature maredeposits, and they are dominated by clinopyroxene(e.g . two small deposits east of Aristoteles Crater ).Small pyroclastic deposits in Group 2 appear toconsist largely of fragmented plug rock material, withinsignificant amounts of highland and juvenilematerials (e.g., Gaddis et al and references therein ,2003). Group 3 mafic bands are centered near 1.0micron, have depths of ~5 to 7%, are relatively broadand asymmetrical, and are probably multiple bands.Spectra of Group 3 deposits are dominated by olivineand orthopyroxene; examples of Group 3 smallpyroclastic deposits are those of J. Herschel Crater(62°N, 42°W) and the well known Alphonsus Crater(Fig. 17).

On the other hand, in a Strombolian eruptionexplosive decompression occurs as the pressure isreleased and the magma and gas rise in anexpanding column of erupting material. For the moonthe particles will spread out over an area roughly sixtimes larger on the Moon than they would for asimilar eruption on Earth. Larger fragments will bedeposited closest to the vent. A Strombolian eruptionis consistent with the volatile coated spheresreturned from the Apollo 17 landing site. Among thelargest of the dark mantle deposits are Aristarchusplateau, Mare Humorum, South Mare Vaporum andSulpicius Gallus deposits.

FFiigguurree 66 ::

stratrigraphy of lava flows and scoria producedfrom Paleostromboli and Vancori volcano (image bythe author) .

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FFiigguurree 77::

the Vancori volcano has produced explosiveeruptions. Ignimbrites, lapilli, solidified lava andpyroclastic deposits are apparent (image by theauthor).

FFiigguurree 88::

Volcanic products (scoria and lava flows) fromNeostromboli volcano (image by the author)

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FFiigguurree 99::

the flank of the ancient Vancori volcanocollapsed and was filled with volcanic productsof Neostromboli. The surface is covered with

FFiigguurree 1100 aa aanndd 1100 bb :

The crater 1 with small yellowish patches remains ofNeostromboli volcano. In the two images the plumesproduced by small Strombolian eruption are apparent(images by the author).

(a)

(b)

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FFiigguurree 1111

Andesite fromStromboli (privatecollection of theauthor)

FFiigguurree 1122

scoria from a Strombolian eruption(private collection of the author)

41

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FFiigguurree 1133::

different eruption materialfrom Lipari. Obsidian(private collection of theauthor)

FFiigguurree 1144 aa..

The obsidian texture. The sampleswere collected in Lipari (privatecollection of the author)

FFiigguurree 1144 bb..

Pumice. The samples were collectedin Lipari (private collection of theauthor)

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FFiigguurree 1155::

a strombolian eruptionimage from Crater 1. Imagetaken by the author fromPunta Labronzo.

FFiigguurree 1166

scheme of a Strombolianeruption

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RReeffeerreenncceess[1] Aiuppa, A. & Federico, C., 2004. Anomalous magmatic degassing prior to the 5th April 2003 paroxysm onStromboli. Geophysical Research Letters 31, L14607, doi: 10.1029/2004GL020458.

[2] Alean J. and Fulle M., 2008http://www.swisseduc.ch/stromboli/volcano/photos/photo1005a­en.html

[3] Bertagnini, A., Metrich, N., Landi, P. & Rosi, M. (2003). Stromboli volcano (Aeolian Archipelago, Italy): an openwindow on the deep­feeding system of a steady state basaltic volcano. Journal of Geophysical Research 108(B7),2336, doi: 10.1029/2002JB002146.

[4] Carapezza, M. L., Inguaggiato, S., Brusca, L. & Longo, M., 2004. Geochemical precursors of the activity of anopen­conduit volcano: the Stromboli 2002–2003 eruptive events. Geophysical Research Letters 31, L07620, doi:10.1029/2004GL019614.

[5] Francalanci, L., Manetti, P., Peccerillo, A., Keller, J., 1993. Magmatological evolution of the Stromboli volcano(Aeolian Arc, Italy): inferences from major and trace element and Sr isotopic composition of lavas and pyroclasticrocks. Acta Vulcanologica 3, 127­151.

[6] Gaddis, L. R., Staid, M. I., Tyburczy, J. A., Hawke B. R., Petro, N. E., 2003. Compositional analyses of lunarpyroclastic deposits, Icarus, vol. 161, no. 2, pp. 262­280, 2003.

[7] Gaddis L.R., C. Rosanova, B.R. Hawke, C. R. Coombs, M. Robinson, and J. Sable, 1998. Integratedmultispectral and geophysical datasets: A global view of lunar pyroclastic deposits. New Views of the Moon, LPI,pp. 19­20 September, 1998. LPI, pp. 19­20 September, 1998.

[8] Head, J.W., III, Wilson, L., 1979. Alphonsus­type dark­halo craters: morphology, morphometry, and eruptionconditions, in: Proc. Lunar Planet. Sci. Conf. 10th, pp. 2861–2897.

[9] Hornig­Kjarsgaard, I., Keller, J., Koberski, U., Stadlbauer, E., Francalanci, L. & Lenhart, R., 1993. Geology,stratigraphy and volcanological evolution of the island of Stromboli, Aeolian arc,Italy. Acta Vulcanologica 3, 21–68.

[10] International Geoscience Programme http://www.geo.unimib.it/IGCP508/IGCP508_Areas_Stromboli.htm

[11] Pasquaré, G., Francalanci, L., Garduño, V.H., Tibaldi, A., 1993. Structure and geological evolution of theStromboli volcano, Aeolian islands, Italy. Acta Vulcanologica, 3, 79­89.

[12] Tibaldi, A., Pasquaré, G., Francalanci, L., Garduño, V.H., 1994. Collapse type and recurrence at Strombolivolcano, associated volcanic activity, and sea level changes. Accademia dei Lincei, Atti dei Convegni Lincei,Roma, 112, 143­151.

[13] Weitz, C.A., Head, J.W., III, Pieters, C.M., 1998. Lunar regional dark mantle deposits: geologic, multispectral,and modeling studies. J. Geophys. Res. 103, 22725–22759.

[14] Wilson, M, Condliffe, E, Cortes, J. A, & Francalanci, L., 2006. The Occurrence of Forsterite and Highlyoxidizing conditions in Basaltic Lavas from Stromboli Volcano, Italy. Journal of Petrology, 47, 1345­ 1373

[15] Wood, C.A, 2008. A LUNAR PROCESShttp://the­moon.wikispaces.com/LPOD+June+16%2C+2008

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PPaarrttiiaall SSoollaarr EEcclliippssee OOccttoobbeerr 2233,, 22001144By Mike Wirths and Pamela Weston

A partial solar eclipse occurred this year. In the image you can make out the mountainous regions of thelunar south pole silhouetted against the solar disk. The huge sunspot AR 2192 is also detectable and it wasimaged.

PPaarrttiiaall ssoollaarr eecclliippssee LLuunntt 115522mmmm ssoollaarr ssccooppee ((MM.. WWiirrtthhss))..

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SShhoott ooff tthhee eecclliippssee wwiitthh aa CCaannoonn 66DD aanndd aa440000mmmm lleennss,, BBaaaaddeerr ssoollaarr ffiilltteerr ((PPaammeellaaWWeessttoonn))..

LLuunntt 115522mmmm ssoollaarr ssccooppee ((MM.. WWiirrtthhss)).. TThheeBB&&WW iimmaaggee ooff tthhee hhuuggee ssuussppoott.. AA ssttaacckk ooff330000 oouutt ooff 11770000 ccaappttuurreedd..

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Lunar south pole with crater Neumayer at the point of maximumlibration

By Rik Hill

The small arrow marks the point of maximumlibration giving the flat bottomed craterNeumayer, just above the arrow, good exposure.Above and to the right of that crater is the 99 kmdiameter crater Helmholtz and to the left of thatis the crater in a crater Boussingault andBoussingault A. At 134 km diameter this is thelargest crater in this image. Even further to theleft is Boguslawsky. Going north fromBoguslawsky is another flat bottomed crater,Manzinus and to its right is Mutus with the twosmaller craters (17 & 24 km) in the bottom.Below Buguslawsky is the 117 km diameter,Demonax in one of the best presentations I haveseen of it. Immediately to its left and half filledwith shadow is Scott and right below Scott,almost all filled with shadow is Amundsen, asyou might expect if you know your polarexploration history. A line through the center ofScott and Amundsen and extended oneAmundsen diameter will take you to the exactpole, which is on the limb of this lighting andlibration. Above Scott is Schomberger. Thisimage is a montage of 2 images each made from600 select frames from 3000 frame AVIs takenwith the SKYRIS 445M camera. Stacking wasdone with AutoStakkert and final processingdone with GIMP. The montage was put togetherwith AutoStitch. Using LROC QuickMap I wasable to identify craters to 1km diameter in theregion of Mutus.

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A small Meniscus Hollow field associated with extrusive volcanismin south eastern Mare Tranquillitatis

By Barry Fitz­Gerald Geologic Lunar Research (GLR) group

AAbbssttrraacctt

Lunar extrusive volcanism can take the form oflocalised (resulting in positive relief features) orregional (producing widespread low relieftopography) pyrocastic activity, effusive domeformation or widespread basaltic flows togetherwith a host of other associated structures such assinuous rilles. A more enigmatic form that may owetheir formation to volcanic activity are the structuresknown as Meniscus Hollows, the most well knownexample being 'Ina' in Lacus Felicitatis. A numberof these structures have been previously reportedfrom Mare Tranquillitatis, and this article describesthe close association between what is interpretedto be a small effusive lobate flow of volcanic originand a small field of Meniscus Hollow structures. Apossible link between their spatial occurrence andmechanism of formation is discussed.

The imagery provided by the Lunar ReconnaissanceOrbiter Camera has resulted in the discovery ofnumerous previously unknown features on the lunarsurface. Many of these features are believed to bevolcanic in origin, providing evidence of widespreadactivity over the course of lunar history. These featuresrange from previously unrecognised pyroclastic deposits(Gustafson et.al 2012) effusive volcanic structures suchas lunar domes (Lena, R and Lazzarotti 2014). Includedin this list are the enigmatic 'Ina like' Meniscus Hollowswhich are interpreted as being the result of the releaseof residual volatile or radiogenic gasses, and probablyform some of the youngest features on the lunar surface(Stooke, 2012).

The current article describes an unusual complex withinthe Lamont mare ridge structure of Mare Tranquillitatis,approximately 60kms to the south­east of the craterArago (Fig.1). This complex consists of two different

structures, one a suspected viscous flow likefeature associated with a possible source vent,and another consisting of a field of MeniscusHollow (MH) structures associated with whatappears to be a submerged impact crater.

Both structures are associated with localiseddeposits of dark mantle material (DMD) as seen inthe Clementine UVVIS Multispectral Mosaicimages, adding support to the hypothesis thatthese structures are volcanic in nature.

The northernmost structure takes the form of alozenge shaped, flow like feature, measuringapproximately 8kms east­west and 5kms north­south (Fig.2). The upper surface of the feature isflat and table like, with a crater density similar tothat of the surrounding mare. The margins of thefeature exhibit a lobate form, with two prominentlobes to the north and smaller lobes around theremaining edges. Interestingly the two northernlobes partially overlap (Fig.3), with the westernlobe superimposed on the eastern one, suggestingthat the latter pre­dates the former (i.e the easternlobe is younger).

The surrounding surface of mare lavas have alocally downwards slope towards the centre of theLamont structure, with no indications of anyprotruding highland materials with which thestructure could be related or form part of. Theslope of the features margins is of the order of 25º,with the lower part forming what appears to be adebris or talus apron due to mass wastage. Theeastern part of the structure is dominated by threecraters, two of which appear to be impact craters inthe region of 700m in diameter, the third appearingmore sub­circular and subdued in nature and in theregion of 900m in diameter (Fig.4). The possibilityof this larger crater being a source vent will bediscussed later.

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Fig.1

Location of the volcanic complexdiscussed in text. Note the mareridges which form the westernboundary of the Lamont structure.

Fig.2

SELENE image of suspected flow likefeature (SF) showing lobate margins,and submerged crater (SC) whichappears to be the focus of localisedMeniscus Hollow activity.

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Fig.3

LRO Quickmap view of northernmargin of flow the like feature.Note Debris Apron (DA) mantlinglower slopes and the overlappingrelationship between the westernand eastern lobes (OL).

Fig.4

LRO Quickmap view of three craters at theeastern end of the flow feature underdiscussion. Note the more subdued natureof the crater lower left.

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East of these three craters the structure takes on amore subdued and less well defined nature, butlobate edges are still visible especially along thesouthern margin. Approximately 2kms to the south ofthis trio of craters is the submerged circular structurenoted above (Fig.5).

This is morphologically identical to the manywidespread examples of submerged mare impactcraters and suggests the flooding of a pre­existingimpact crater by later low viscosity lava, followed bylater subsidence of the lava levels, leaving the centralpart of the crater slightly depressed relative to thesurrounding mare surface (Masursky et.al, 1978).

The structure appears slightly oval in shape, with anapproximate diameter of some 3.5kms. The westernrim is more elevated above the mare surface (byabout 17m) than the eastern rim (1 to 2m) this maybe a consequence of the general regional slopetowards the east and the centre of the Lamontstructure. The inner wall of the crater consists of a200m wide slope with the subtle 'tree bark' textureindicative of mass wastage. Around the westernsection of the crater, and some 5m below the highestpoint, a narrow discontinuous moat or fissure isvisible. This moat appears to be the focus of some ofthe numerous small MH structures that surround thiscrater (Fig.6). Similar structures have been observedin other mare flooded craters (Schultz, 1972) andmay be interpreted as being a result of thesubsidence of the mare infill. This would suggest apossible conduit via subsurface fractures to deeperlevels within the structure.

These small MH structures range from small pits, tolarger irregularly shaped depressions of the order of100m in dimension. They appear to consist of areaswhere the superficial regolith is absent, revealing anunderlying surface that is featureless at the resolutionof the imagery. The floor of the larger hollows mayhave a sprinkling of loose boulders (Fig.7).

A larger MH structure can be seen to the north­north­west associated with the rim and inner walls and floorof a small crater. This appears to be a small impactcrater some 350m in diameter, that has been heavilymodified by MH activity. In this case, a high albedo

Fig.5

Image taken from LROC Observation M1108132323Lof submerged circular structure identified in Fig.2.Note occurrence of Meniscus Hollow activity (yellowarrows) particularly associated with western margin ofstructure.

Fig.6

Image taken from LROC Observation M1108132323Lof submerged crater showing western rim (R), moat(M), Debris Apron with tree bark texture (DA) andcrater floor (F). Note Meniscus Hollows associatedwith moat.

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featureless substrate appears to be exposed overthe northern part of the crater with the higher slopesof the inner wall bearing the characteristic 'etched'appearance typical of small MH features.

Fig.7

Details of Meniscus Hollow pits associated with the western section of the submerged crater (LROCObservation M1108132323L).

Fig.8

Detail of MH modified crater on NNW rim ofsubmerged crater (LROC Observation M1108132323L).

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A small talus cone of boulders can be seen onthe crater floor, whilst the inner eastern wallexhibits what appears to be two cleft likestructures running parallel to the crater rim andsome 80­100m in length. These clefts mayrepresent areas where material has beenremoved by some process – possibly related tothe gas release implicated in MH formationgenerally. An interesting irregular MH structurecan be seen located just to the east of theeastern rim of the submerged crater. This isapproximately 200m in length, with irregularmargins and a floor consisting of a smoothsubstrate, with in places, irregular low relief andpossibly isolated boulders. This structure has asmooth featureless low albedo aureolesurrounding it, extending out approximately 50­100m beyond the visible sharp rim of thedepression (Fig.9).

The remainder of the area surrounding thesubmerged crater contains additional small MHtype structures, mostly on the scale of between5 and 25m, some irregular and others withsharply defined edges. The floors (where visible)are similar to those already described with asmooth featureless surface with the suggestionof some superimposed boulders. The largestareas of MH appear to be associated with 2impact craters both approximately 1km indiameter and lying within 1km of the submergedcrater. The first of this pair lies to the south­east,and bears signs of extensive MH activity in theform of high albedo patches on the westerninner wall, apparently associated with aconcentric 'bench' visible around the innercircumference of the crater (Fig.10). The activity,as noted appears largely confined to thewestern half of the crater wall, where the 'uppersurface' of the bench appears to be covered in alow albedo smooth material similar to theaureole noted in Fig.9.

The second crater to the south­west is similarlymodified by MH activity, but in this case most ofthe circumference of the inner crater inner wall

Fig.9

Detail of MH to the east of submerged crater. Note thesmooth low albedo aureole.(LROC Observation M1108132323L).

Fig.10

Small MH modified crater to the SE of submergedcrater. Note the 'bench' located on the inner crater wall,and MH activity concentrated in the western half.(LROC Observation M1108132323L).

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is affected, with large patches of high albedomaterial surrounded by smoother low albedodeposits. Some of the high albedo patches areclearly heavily boulder strewn. Vague indicationof a 'bench' type structure on the slopes of theinner crater wall are visible, especially to thesouth, but the extensive modification and downslope movement may have obscured evidenceof the feature elsewhere.

It might be hoped that the different units withinthis complex might exhibit unique multispectralsignatures to assist in identifying their origin andcomposition. A glance at Fig.12 reveals that thisis partially the case, with indications of lowalbedo, possibly mafic pyroclastic deposits insome areas, but little to distinguish the proposedhigh viscosity lobate flow from the surroundingmare.

Fig.11

Small MH modified crater to the SW ofsubmerged crater. Note MH activityaround circumference of inner wall(LROC Observation M1131694020Loblique view looking west).

Fig.12

Composite consisting of SELENE image ofarea under discussion and superimposedClementine UV­VIS Multispectral Mosaic(R=1000nm, G=900nm, B=415nm). Notedark possibly mafic material concentratedaround craters identified in Fig.4, andwestern margin of submerged crater.

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As can be seen, darker, possibly mafic pyroclasticmaterial is evident in the area of the three cratersnoted in Fig.4, with a particularly dense concentrationto the south of the more subdued of the three. Thisdenser concentration corresponds to a spine ofmaterial that appears to be superimposed (togetherwith a more tabular area of elevated materialimmediately to the north) on the suspected viscousflows, and may itself represent a late stage extrusionof even more viscous material (Fig.13).

A further dark, possibly pyroclastic signature is visibleassociated with the western rim of the submergedcrater, but at the current resolution it is impossible toassociate any of the MH structures with these darkerareas.

DDiissccuussssiioonn

The close proximity of the suspected viscous flowstructure, possible source vent(s) and the MH activitysurrounding the submerged crater are suggestive butnot conclusive evidence of a common cause. Thepossible connection between volcanic areas andareas of MH activity such as to the west of TobiasMayer has been commented on previously Stooke(2012), though it is fair to say that alternativemechanisms for the production of MH's (such as inthe classical area Ina) have been proposed (Garryet.al, 2012 and Schultz et.al, 2006). The presence ofthe suspected viscous flow superimposed on themare surface suggest that it's extrusion (if this isindeed the correct interpretation) occurred followingthe emplacement of the mare lavas and thusrepresents late stage volcanism. Similarly, the MHactivity clearly post dates mare emplacement, theflooding of the submerged crater and subsequent lavawithdrawal. Such late stage volcanism might beexpected to produce a highly derived, acidic lava.Such effusive products might be expected to exhibit adifferent spectral signature to the surrounding marebut no such difference is visible, a potential counterargument to the present interpretation. Lawrence etal. (2013) however point out that there is nodifference spectrally between the domes and cones of

Fig.13

Spine of material (SP) corresponding in position todark concentration of possibly mafic material as seenin the Clementine data. To the north a lower tabularstructure (TA) of comparable morphology.

the Marius Hills and the surrounding mare, andsuggest that a difference in mode of eruption ratherthan difference in composition is responsible for theobserved variation in morphology. This situationmay apply to the present case to some degree. Theobserved morphology consisting of lobate fronts,with evidence of lobes overlapping (suggestive oftheir formation being separated temporally) is againhighly indicative of a series of viscous flow. Thepresence of the dark possible mafic pyroclasticmaterial in the area of the subdued crater shown inFig.4 adds further support to the volcanicinterpretation offered here.

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Fig.14

Quickmap GLD100 plot from west to east across the suspected viscousflow (left) and the suspected submerged crater (right). Note scales notidentical.

Further information regarding the relative dating of thestructures can be gleaned from the Quickmap GLD100plots across both the suspected flow and thesubmerged crater. As can be seen from Fig.14, bothare located on terrain with a regional dip towards theeast, consistent with the down­warping of the centralpart of Lamont, a process that gave rise to theprominent circular wrinkle ridge system that definesthe feature. In the case of the suspected viscous flow(Fig.14 left) formation must have pre­dated the down­warping as otherwise the flow would have occurredagainst the local topographic gradient (i.e. up­hill).Similarly the profile of the submerged crater (Fig.14right) shows the floor sharing the same dip towardsthe east as the regional one, indicating that lavainfilling pre­dated the down­warping, as otherwise ahorizontal infilling would be observed. Both of theseobservations bracket the origin of these structures toafter the final mare emplacement, but prior to thesubsidence of the central part of the Lamont structure.

The MH's in the current example are a heterogeneouscollection, with some having a well defined edges,others appearing quite irregular. Most have a welldefined aureole of smoother, sometimesconspicuously darker material (such as the exampleseen in Fig.9), whilst some of the smaller exampleslack any conspicuously darker margins. This MHactivity would appear to be the most recent form ofactivity in this area, with the more conspicuous darkaureoles being devoid of any superimposed craters.This is consistent with the exceedingly recent dates

proposed for similar structures such as Ina(Schultz et.al, 2006). Whilst heterogeneous inform, most of the MH's in the present exampledisplay a common trend in being located on eitherthe inner crater wall of the submerged crater (andparticularly with the 'moat' structure mentionedabove) or the inner crater walls of a number ofsmaller, younger impact craters in the immediatesurrounding area such as those in Fig's 8, 10 and11. These smaller craters also poses ananomalous inner wall with the 'bench' typestructure possibly being analogous to the 'moat' inthe submerged crater.

These inner crater wall features may represent thesurface expression of circumferential faults,fractures and fissures associated with the initialcrater forming event. As such they may provideconduits for the escape for the residual volcanic orradiogenic gasses which are suggested as beingresponsible for the formation of MH's elsewhere byremoval of the finer regolith component. Curiouslyno MH's are visible within the submerged crater, apossible consequence of the presence here of athicker capping of mare lavas. The MH illustratedin Fig.9 is however the exception thatdemonstrates that not all of these features areassociated with peripheral crater fracture systems,but can also be found on the nearby mare surface.

The presence of the dark, possibly pyroclasticmaterial in the areas occupied by the MH's would

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support the residual volcanic gas interpretation offormation as opposed to the release of radiogenicallyderived gas, though this is speculation and thecoincidence of the two forms of gas release cannot beruled out by this study.

Another example of a suspected viscous flowstructure and MH activity can be seen approximately19kms to the south of the crater Natasha and withinthe volcanic landscape surrounding Tobias Mayer.Here a small roughly rectangular elevated plateau,with talus rich lobate margins suggestive of viscouslava flow fronts, can be seen perched on top of asmall massif which corresponds in position to a darkpossibly pyroclastic deposit as seen in the Clementinedata (Fig.15).

Whilst it is not intended to discuss this area in anygreat detail, it is worth commenting on the parallelsbetween what can be seen here and the structures inthe Lamont example. Both areas display the presenceof a structure indicative of formation by a processinvolving viscous flow(s) of possible volcanic origin.Both areas share a mantling of dark possiblypyroclastic material, and both have associated MHtype modification to what appear to be nearby impactcraters. An examination of some of the other cratersin the area shown in Fig.15 and 16 shows indicationsof MH activity in a zone within the inner crater wallsas is seen in the Lamont area. This brief comparisonserves to illustrate that this combination of features isnot unique and may hint at similar geological activityin both areas. It would also suggest that a search forfurther areas of MH activity could be focussed onareas containing suspected late stage effusivevolcanic activity and viscous flow structures.

Fig.15

Composite image consisting of LRO Quickmapimage of small massif and rectangular plateau southof Natasha superimposed Clementine UV­VISMultispectral Mosaic (R=1000nm, G=900nm,B=415nm). Note dark possibly pyroclastic materialcorresponding in position to the massif.

Fig.16

LRO Quickmap image of the rectangular plateaudiscussed in text (left) – note lobate talus coveredmargins and inset box showing location of small MHmodified crater shown in enlargement (right).

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RReeffeerreenncceess

Garry, W. B.; Robinson, M. S.; Zimbelman, J. R.; Bleacher, J. E.; Hawke, B. R.; Crumpler, L. S.; Braden,S. E.; Sato, H., November 2012. The origin of Ina:Evidence for inflated lava flows on the Moon. Journalof Geophysical Research 117: E00H31.

Gustafson, J.O., Bell , J.F., Gaddis, L.R., Hawke, B.R., Giguere, T.A., 2012. Characterization ofpreviously unidentified lunar pyroclastic deposits using lunar reconnaissance orbiter camera data. J.Geophys. Res. 117, E00H25

Lawrence, S., Stopar, J., Hawke, B., Greenhagen, B., Cahill, J., Bandfield, J., Jolliff, B., Denevi, B.,Robinson, M., Glotch, T., 2013. LRO observations of morphology and surface roughness of volcaniccones and lobate lava flows in the Marius Hills. J Geophys Res­Planet. 118 (4):615­634.

Lena, R. and Lazzarotti, P, 2014. Domes in northern Mare Tranquillitatis: Morphometric analysis andmode of formation. Selenology Today, Issue 35.

Masursky, H., Colton, G. W., and El­Baz, F. eds. 1978. Apollo over the Moon: A view from Orbit.Washington, D.C.: NASA Scientific and Technical Information Office (Special Publication 362)

Stooke, P. J., 2012. Lunar Meniscus Hollows. 43rd Lunar and Planetary Science Conference, heldMarch 19­23.

Schultz, P., 1972. Moon morphology. University of Texas Press, Austin, Texas­London, pp 340­341

Schultz, P. H. Staid, M. I. Pieters, C. M., November 2006. Lunar activity from recent gas release. Nature444 (7116): 184–186

AAcckknnoowwlleeddggeemmeennttss

LROC images and topographic charts reproduced by courtesy of the LROC Website athttp://lroc.sese.asu.edu/index.html, School of Earth and Space Exploration, University of Arizona.

All multispectral images courtesy of the USGS PSD Imaging Node at http://www.mapaplanet.org/

Selene images courtesy of Japan Aerospace Exploration Agency (JAXA) at:http://l2db.selene.darts.isas.jaxa.jp

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TThhee NNeeccttaarriiss MMuullttii­­RRiinngg IImmppaacctt BBaassiinn:: FFoorrmmaattiioonn,,MMooddiiffiiccaattiioonn,, aanndd RReeggiioonnaall GGeeoollooggyy

by Richard H. Handy

IInnttrroodduuccttiioonn

I must confess to being totally fascinatedby the Nectaris Multi­Ring Impact Basin.Those dramatic set of nested concentricscarps, massifs and plateaus separatedby lava and impact melt veneered moatssurrounding a relatively small embaymentof mare lavas. They are surprising relicsfrom an impact event that occurred nearly3.9 billion years ago. Surprising becausemost basins do not have obvious orstrongly defined multi­ring scarps, despitethe fact that they all originally possessedthem. Presumably these arecharacteristics that have been eitherflooded by subsequent lava flows, erodedaway by later impacts, or buried by ejectablankets. The Orientale basin is a classicexample of a multi ring impact basin witha relatively small area of maria duemainly to its youth, unfortunately forearthbound observers, its scarp rings andmoats are seen in profile, close to thelimb, depriving us of a plan view of theentire basin. The Nectaris basin, howeveris well placed for our observations,located near the middle of the south eastquadrant in the northeast extension of theSouthern Highlands. (See figure 1). Thiswork examines the geological units,topography, petrography and formation ofthe Nectaris basin. A full list of books andarticles published in the literature thatwere used to produce this work arecompiled in the reference section.

FFiigguurree 11

The Nectaris Multi­Ring Basin November 9, 2014. Mosaic imageswere acquired between approximately 9:45 and 10:20 UT usingthe author’s Alter M815 Maksutov telescope and LumeneraSkynyx2.01Mvideocamera.

TThhee GGeeoollooggiiccaall UUnniittss ooff tthhee NNeeccttaarriiss bbaassiinn

Figure 2 is a color coded image representing the main Nectarisbasin geological units based on a sketch from page 69 of “TheGeology of Multi­Ring Impact Basins: The Moon and otherPlanets” by Paul D. Spudis, Cambridge Planetary ScienceSeries, Cambridge University Press, 2005. In this coloredimage, deep blue is the Mare Material, yellow is the CraterMaterial, violet is the Smooth Plains, orange is the Descartes

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Formation, Green is the Janssen Formation,red is the Hilly and Pitted Material, bluegreen is the Plateau Material, pink is theTerra Plains, black is the Massif Material andthe gray of the uncolored surface representsthe Undifferentiated Terra. Although adetailed examination of each of the mainfacies is beyond the scope of this article,their particular pattern suggests that a broadlens of material covers the zones to the westof the Altai Scarp with what appears to beanorthosite excavated from the Nectarisimpact site. Apollo 16 confirmed these ideaswhen they retrieved samples from the KantPlateau. The Censorius Highlands are also arich source of high aluminum and maficchemistries, indicating a deep excavationand redeposit as part of a broad ejectablanket with similar origin to the Kant Plateaumaterials. The crater materials displays apattern that suggests that the smaller 10 to30 kilometer craters scattered around thebasin are not random impacts. Theirclustering in the zones outside the centralmare indicates instead that these arepredominately basin secondaries.Presumably the secondaries that were closerto the basin center have been buried by laterflows of mare lavas. Besides the freshappearance of the scarp rings, the presenceof platform massifs is also a hint that longterm changes in the asthenospherecontinued long after the basin initially formed.These massifs rafted to their isolatedpositions by riding the flows of a deeperintrusion of mare basalts. The system ofrings around both the Fecunditatis andTranquillitatis basins was probablyresponsible for the development of theseisolated plateaus by allowing fracturedcrustal plates to extrude lava as they shiftedabout on the aesthenosphre. This style oflunar tectonics is regional in nature, not aglobal system of constantly moving lithicplates riding atop a continuous movingmantle such as the case for the Earth’sGlobal Plate tectonics.

FFiigguurree 22

A color coded image based on a sketch by Paul D. Spudis inhis classic volume “The Geology of Multi­Ring ImpactBasins”, Cambridge University Press, Copyright 2005 ref:pag. 69.

NNeeccttaarriiss BBaassiinn TTooppooggrraapphhyy

Within the five basin rings currently accepted as artifacts ofthe Nectaris impact are a set of topographically distinctregions that are associated with both the impact event aswell as those features related to the later phases ofmodification, including mare basalt infill of the nascent basinand the inner rings interior to the main topographic rim,rejuvenation of the scarp rings as well as very long termadjustments to the regional isostacy. Therefore, the terrainreflects all these elements, some being common to all majorlunar basins and others being unique to the thermal andgeological environment of the Nectaris impact. Elevation

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data from Lunar Reconnaissance Orbiter (LRO)LOLA (Lunar Orbiter Laser Altimeter) data show thatthe highest elevations (3.5 to 4.5 km above themean lunar diameter) are immediately exterior tothe Altai ring in a broad lens or fan that is especiallyprominent in the highlands to the west and south ofthe basin. To the northeast, an isolated plateau andhilly region, the Censorius Highlands, remains as aneroded and heavily cratered continuation of thisgiant basin ejecta blanket. The green colored terrainin this image is about one kilometer lower at 2.5 km,while the turquoise color is representative of theelevations that correspond to about 750 meters,those associated with the maria. Violet representsthe deepest elevations, approximately 3 kilometerslower than the lunar mean diameter. It is clear tosee that the north and eastern components of thisblanket were either areas of paucity of the densityof material in the ejecta curtain or were initiallyformed in situ and were later subsumed by lavasfrom Mare Fecunditatis and Mare Tranquillitatis.Both of these factors could have played out duringthe long evolution of the basin.

The annular inter scarp zones, what arereferred to informally in this article as the “moats”,descend in discreet steps of elevation (see Figure

4) from the main topographic rim at 4000 metersabove the mean lunar diameter, followed by the firstinner annulus shelf which is 1000 meters lower inelevation, the second inner shelf is another 1000meters lower yet and the third annulus is 750 meterslower as one ventures inward from the maintopographical rim. In this sense, inner basins ringsand moats are the giant equivalent to the terraces ofcomplex craters, which bear relation to the geneticsof these features, i.e, mass wasting of the transientcrater rim by the force of gravitation. Obviously, theextreme energy regime of basin producing impactsimpose important morphological differences in thestructures of these major classes of impact eventsseen on the surface of the Moon. Figure 3 is animage combination of LRO LOLA elevation data ofthe basin with simulated northern lighting appliedusing Lunar Terminator Visualization Tool (LTVT),freeware software developed by selenologist JimMosher. The image was created by Irish selenologistand author John Moore who kindly provided its usefor this article.

FFiigguurree 33

Lunar ReconnaissanceOrbiter (LRO) image of theNectaris Basin with colorsrepresenting the regionalelevations derived fromLOLA data sets. Red is thehighest, orange and yelloware intermediate heights,greens are lower plains,blue are the mare areasand the basin center andsome peripheral craters areviolet, the deepest features.The light was recreatedfrom an unnatural direction(from the north) using JimMosher’s freeware softwareLTVT. Image courtesy ofJohn Moore.

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FFiigguurree 44

Schematic representation ofa cross section through abasin from the maintopographic rim to its center.The arrows indicate thedirection of movement oflarge annular zones, theinter scarp zones informallyreferred to as the “moats” inthis article. Sketch drawn bythe author.

TThhee PPeettrroollooggyy ooff tthhee NNeeccttaarriiss BBaassiinn

Most of the data acquired to characterize the mineralconstituents of the Nectaris basin were derived fromorbital or ground based remote sensing. The Apollomissions, Lunar Prospector and then the LunarReconnaissance Orbiter have extended theopportunity to analyze Nectaris basin deposits. TheApollo16 mission sampled material directly from theKant Plateau, offering a unique opportunity tocompare mineral analysis based on remote sensingcomparisons to laboratory results. The product of thissynthesis allows a thorough mineral classification forthe Nectaris facies.Northeast of the basin center, the CensoriusHighlands, in the area of the crater Capella, is aprovince characterized by its Very High Alumina(VHA) anorthositic deposits. Thorium deposits hereare some of the highest in any isolated highlandsarea. Its prominent mafic component is thought to berelated to the depth of crustal penetration by theNectaris impactor. In contrast to Orientale, whichlacks this signature, the thermal conditions in itstarget area must have cooled enough for thelithosphere to thicken. And due to the downwardmigration of the asthenosphere (also named asaesthenosphere) during the period of the Orientaleimpact, mafic components from the deepestexcavation of the transient cavity should not bepresent in its distal deposits, as the mineral dataindicates.

To the northwest, a similar province, the KantPlateau, in the region around the crater Descartes,is also anorthositic in composition and similar tothe Censorius Highlands, except that it has ahigher proportion of alumina to silicon, in fact thehighest ratio for any such deposit on the Moon.However, in stark contrast to the CensoriusHighlands, the levels of thorium measured byremote sensing as well as by laboratory analysisof Apollo 16 samples indicate that this provincehas the lowest thorium levels, exceeding anyregion on the near side, and is comparable withthe lowest percentages in the far side highlandswith respect to this component. In both regionsthese results indicate that these materials wereoriginally part of the upper anorthositic crust in thetarget zone, and along with a mixture with uppermantle components, which were deposited in theirpresent location by the force of the Nectarisimpact.Interestingly, as one moves beyond the KantPlateau further west past the Descartes Formationwhich is predominately composed of pureanorthosite, the levels of thorium and maficcomponents increase. Here the rock types aresignificantly different than the Nectariscomponents and the surface chemistries arethought to reflect subsequent pre­Imbriumvolcanism and distal deposits and mixing ofmaterials from the Imbrium impact as well as the

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heterogeneous make up of the southern near sidehighlands. In general, the Nectaris facies arecomposed predominately of anorthositic and LowPotassium Fra Mauro (LKFM) components in a ratioof 3:1 respectively. A less significant component butone that must accounted for in the regional analysis,is the mare basalt contribution that increases as oneapproaches the basin center. Moreover, this maficconstitution, along with the KREEP (Potassium,Rare Earth Elements, and Phosphorus) componentpresent in the highland areas suggest that marebasalts were present at the target location,presumably in pre­existing basalt deposits fromMare Tranquillitatis and Mare Fecunditatis. Becauseno ultramafic materials were identified in the spectraldata for the distal units of the Nectaris facies, it isbelieved that this result points to an impact that didnot excavate deep enough to penetrate the uppermantle, but rather was confined to the middle andlower lithosphere.

TThhee FFoorrmmaattiioonn ooff tthhee NNeeccttaarriiss bbaassiinn

Figure 5 is an image of the basin annotated to showthe approximate location of the main topographic rimand two inner scarp rings. There are also tworecognized rings outside the boundary of the AltaiScarp which are not shown in this image. Note thenested concentric pattern of the scarps. How did thisdistinctive structure form? Upon first impact of this35 kilometer asteroid, all craters that had formed inthe impact location were swept clean of the surface.The impactor was nearly totally vaporized in ablinding explosion as a huge spherical melt zoneformed in the center of what would become a 500kilometer by 35 kilometer deep transient crater.When the transient crater reached its greatestdiameter, the melt zone rebounded into a giantcolumn of melt that was ejected over a hundredkilometers upward, much in the same manner that adrop of water deforms the water surface into a peakas a reaction to the impact of the drop. At themoment of contact, when the asteroid delivered itsfull kinetic energy, the lunar crust literally rose andfell several kilometers as giant seismic ripples liftedand then dropped the lithosphere, fracturing, anddown faulting huge annular zones, consequentlyexposing the scarps. An ejecta curtain, a giant cone

of vaporized impactor and shock melted targetmaterial expanded outward from the transientcrater rim. As the massive ejecta curtain sweptthrough, it mixed with pulverized regolith, creatingfluidized flow fronts, incredibly energetic tsunamisof flowing debris splaying out radially and nearlyhorizontal to the surface. They gouged long linearvalleys and strange braided landforms and teardrop formations as they tore through crater walls,burying what they did not destroy. When the ejectacurtain impacted, the debris blanketed andinundated and covered both large and smallcraters in areas of the lunar surface exterior to themain topographic rim. A rain of secondary impactsfollowed, some taking long arcing trajectoriesbefore impacting several minutes later, hundredsof kilometers away into the distant surroundingterrain, gouging deep linear catenae radial to theimpact center. Vallis Snellius and Vallis Rheita areprominent examples of Nectaris impact sculptures.

An intriguing aspect to the scarp ringspacing is that each succeeding ring diameteroutward from the basin center measures about 1.4times the diameter of the previous ring, the wellknown square root of 2 rule for basin rings. Andwhile there are no simple answers for theexistence of such a relation, it can be understoodas primarily the result of the diminishing energy,expressed as a gradual reduction in the amplitudeof the seismic shock waves as they propagateoutward, dissipating their energy over a wider areaof the crust.

Surprisingly, although the basin was formedin roughly two hours, the lavas that cover MareNectaris took hundreds of millions of years toemplace. Perhaps not as obvious, because theyare not surficial, are the changes that occurreddeep below the crust. Here concentric lenticularfracture zones in the mega regolith provided apath for hot magmas from the lithic/mantleinterface below, feeding the expansion of marebasalt flows, which were extruded layer by layerfor several hundred million years thereafter.

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Figure 5

Approximate location ofthe Nectaris concentricscarp rings includingthe Altai ring and therings interior to it. Thereare rings interior to thecentral ring shownhere, but they havebeen almost entirelyflooded and subsumedby mare lavas. Imageby the author.

In concert with these processes in the lithosphere, werethe changes happening in the lunar asthenosphere.The warmer and denser plastic upper mantle, initiallypushed aside by the force of the Nectaris impact, wouldeventually flow inwards and upwards towards basincenter where the annular crustal zones could beexpected to be tugged in tectonic fashion. Extensionalgraben faults that would develop as the mass ofbuilding mare lavas later depressed and furtherfractured the crust provided sufficient venting ofmagmas to allow changes in aspects of basinmorphology over long periods of lunar geologic history.These modifications, particularly in the areas adjacent

to the scarps, probably occurred in episodicfashion long after the scarps initially formed,rejuvenating the appearance of the rings asregional isostasis was still being established in theevolving thermal environment of the early lunarasthenosphere.The inter­scarp regions, stepped annular zonessometimes referred to as the moats, aredestroyed, buried and broken, medium (about 50km diameter) to small (10 km diameter) cratersthat are covered with a veneer of impact melt

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and/or mare lavas. The moats interior to the maintopographic rim are the most subject to obscuration bymare basalt lavas that have covered these zonespredominately in the north from Mare Tranquillatatisand to the east from Mare Fecunditatis (see Figure 1).Here the jumbled texture of the inter­scarp zones aremuted, and except for a few isolated areas, virtuallycovered by mare lavas. Yet to the south and west ofthe basin the moat zones are clearly exposed,displaying a layer of impact melt, the fresh appearanceof its inner scarps belying its advanced age. There aresurprises here, only the partial rims of some mediumsized craters can be seen while almost the entire flooris submerged by ejecta deposits from the basin’sformation. Other craters have only their basin facingramparts remaining; their opposing walls and glacishave been scoured away by the force of thetremendous blast as the ejecta curtain swept through.This image indicates these inter­scarp zones and a fewalmost hidden craters partially submerged by ejecta.

TThhee PPrreesseerrvvaattiioonn ooff tthhee NNeeccttaarriiss SSccaarrpp RRiinnggss

Why is the Nectaris multi­ring impact basin so wellpreserved? Nectaris is a large sized basin with a smallmare area. If measured across its main topographicrim (the Altai Scarp) it is 860 km in diameter, but themare is relatively small with a diameter of only 368 kmand an area of 84,000 square kilometers,proportionately smaller than most near side basins.The Orientale basin displays an even greater paucity ofmare basalts. Was the impactor smaller in diameter?Impactor size might be a major reason that basaltlavas did not completely inundate the rings interior tothe main topographic rim, such as the Imbrium lavashave done to its inner rings. With a smaller impact, thecrust/mantle faults would not be as deep or as widelydispersed in area, reducing the volume of lava eruptedand consequently preserving the multiple scarps. Yetthis seems unlikely because the main topographic rimof Nectaris is commensurate in diameter with a numberof large basins. And given differences in morphologybased on the range of kinetic energies and extremeangles of impact, impactors of similar mass producesimilar sized crater/basin diameters.Does the relative isolation of the Nectaris basin figureinto its preservation? The Tranquillitatis basin to the

north and the Fecunditatis basin to the east arethe only basins close by whose lavas could havemodified Nectaris. It does appear that they haveflooded onto the northern and eastern regions ofthe Nectaris basin obscuring the rings there,however, they have not significantly destroyed themulti­ring scarps to the west and south of themare. Could its location closer to the southernhighlands have meant a thicker crust in the targetregion, slowing the degradation of the basin byimpeding volcanism? This seems plausible, as itplaces Nectaris far from the vast plumbing of theProcellarum and Imbrium regions and a thickercrust would mean the depth of the transient cavitywould not have penetrated as deeply.Consequently the release of magma fromchambers in the sub­lithospheric layer layerswould have been minimal for this area of theMoon. There may well have been some kind oflong term rejuvenation of the scarps that occurredmuch later, when mare lavas subsumed thefractured and broken craters in the moat zones,causing them to collapse, flatten and slidedownslope towards the basin center as a result ofthe building mass of the dense mare basalts andthe movements in the asthenosphere, furtherexposing and accenting their appearance.Whatever the details of the processes responsiblefor its preservation, we are all fortunate to witnessthe spectacular Nectaris multi ring impact basinwhich is not only ancient but remarkably wellpreserved. Within the confines of the maintopographic rim are a magnificent collection ofintermediate size complex craters, all muchyounger than the basin because they superposeit. (See Figure 6).Chief among these are the classic trio, youngTheophilus, mature Cyrillus, and ancient andbattered Catharina. Several hundred thousandyears after the basin was formed, Nectarian agedCatharina was created. Immediately thereafter itappears to have been repeatedly struck bysmaller impactors, and a couple of hundredthousands years later, the impact that producedCyrillus obliterated some of the smaller cratersseveral kilometers to the northeast between thefirst and second scarp ring.

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Theophilus, the Copernican age crowning jewel of thissuperb, partially overlapping group, was emplacedwithin the last billion years or so. Fracastorius, a largecomplex crater of Nectarian age, formed about the timeof Catharina and is now nearly submerged bysubsequent mare basalt flows that breached its easternwalls when the slope of the basin in its vicinityplastically deformed under the load of massive basaltdeposits concentrated at basin center.. Tangent to themain topographic rim, Eratosthenian age Piccolomini(see Figure 7) shows its relatively young featuresespecially when the terminator is close by. A puzzlingaspect is the appearance of its southern walls. Theseterraces appear to reflect the Altai Scarp relief contours,as if the location of Piccolomini’s impact next to the AltaiScarp helped to direct some of the energy of the eventaway from the scarp, preserving its general outline.

FFiigguurree 66

Mosaic image of the centralmare and Nectaris basin scarprings to the west of the mare.The prominent group of threelarge complex craters,Copernican aged Theophilus,Nectarian age Cyrillus andCatharina superpose two innerscarp rings. Image courtesy ofRaffaello Lena, GLR group.

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FFiigguurree 77Lunar crater Piccolomini’s southern walls appear to showevidence of the pre­existing Altai Scarp contours. Image crop fromthe October 12, 2014 mosaic.

Seeing the basin in various waxing and waninglighting can really help to discriminate some of itscomplex annular terrain and radial structure, Figures8 and 9 are image mosaics of the basin regionacquired with my Russian made 8” Alter 815M f/15Maksutov telescope and Lumenera Skynyx 2.0­1Mvideo camera on October 29, 2014 in waxing light,early lunar morning (see Figure 8), again in waxinglight on November 9, 2014, early lunar morning (seeFigure 9), and under waxing light, mid lunar morningon October 29, 2014 (see Figure 10), and finally inwaxing, under mid lunar morning light (see Figure 11).

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Seeing the basin in various waxing and waninglighting can really help to discriminate some of itscomplex annular terrain and radial structure, Figures8 and 9 are image mosaics of the basin regionacquired with my Russian made 8” Alter 815M f/15Maksutov telescope and Lumenera Skynyx 2.0­1Mvideo camera on October 29, 2014 in waxing light,early lunar morning (see Figure 8), again in waxinglight on November 9, 2014, early lunar morning (seeFigure 9), and under waxing light, mid lunar morningon October 29, 2014 (see Figure 10), and finally inwaxing, under mid lunar morning light (see Figure 11).

Figure 8

Mosaic of the Nectaris basinunder waxing (early lunarmorning) on October 29, 2014at 03:30 to 04:45 UT. Imageacquired and processed bythe author.

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Figure 9

Mosaic of the Nectaris basinunder waxing (mid lunarmorning) on November 28, 2014at 01:40 to 03:50 UT. Imageacquired and processed by theauthor.

Figure 10

Mosaic of the Nectaris basinunder waning light (early lunarafternoon) on November 9, 2014at o5:30 UT. Image acquired andprocessed by author.

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Figure 11

Mosaic of the Nectaris basin underwaning light (late lunar afternoon)November 10, 2014 at 05:30 to 06:35UT. Image acquired and processed byauthor.

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AAcckknnoowwlleeddggeemmeennttss

Finally, I would like to extend my gratitude to my friend Raffaello Lena of the GLR Group for both theuse of his superb image mosaic and his consistent support and encouragement. Without his efforts, I wouldnot have been able to pull this article together. Likewise, for the unusually lit LROC image merged withcolored LOLA elevation data and the help and good cheer from my friend John Moore, author andselenographer and an author of several books on near side lunar craters, features and topography as wellas an administrator and contributor for Charles A. Wood's MoonWiki. Thank you both.

There is one individual who is predominately responsible for my continued interest in lunar geology. Hiswebsite aroused my mind and extended my understanding, as he still does today, despite the fact that hissite is no longer being currently published (it is online in archival form). That man is Charles A. Wood. Toyou sir, I owe a debt of gratitude I will never be able to repay. However, I suspect this is true for thethousands of folks who visit his “Lunar Photo of the Day” (LPOD) website every day and who are fortunateenough to have acquired his classic tome “The Modern Moon: A Personal View”, the commentaries thataccompany “The Kaguya Lunar Atlas” that he co­authored with Motomaru Shirao, or those commentaries

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RReeffeerreenncceess

1. “The Geology of Multi­Ring Impact Basins: The Moon and Other Planets” by Paul D. Spudis,Cambridge University Press, paperback edition, Copyright 2005.

2. “The Geologic History of The Moon” by Don E. Wilhelms with sections by John F. McCauleyand Newell J. Trask, U.S. Geological Survey Professional Paper Paper 1348. United StatesPrinting Office, Washington : 1987.

3. “Traces of Catastrophe: A Handbook of Shock­Metamorphic Effects in Terrestrial MeteoriteImpact Structures” by Bevan M. French, Lunar and Planetary Institute Contribution No. 954,Copyright1998byLPI.

4. “The Clementine Atlas of the Moon” by Ben Bussey and Paul Spudis, Cambridge UniversityPress,Copyright2004.

5. “The Modern Moon: A Personal View” by Charles A. Wood, Sky Publishing Corp., Copyright2003.

6. “A Geologic Time Scale 1989” W. Brian Harland, Richard L. Armstrong, Allen V. Cox LorraineE. Craig, Alan G. Smith, David G. Smith, Cambridge University Press, Copyright 1990.

7. “The Face of the Moon” by Ralph B. Baldwin, University of Chicago Press, copyright 1949.

8. “Geological Map of the Nectaris Basin and its Deposits” by M.C. Smith and Paul D. Spudis,Department of earth and Planetary Sciences, University of Tennessee, Lunar and PlanetaryInstitute, 44th Lunar and Planetary Science Conference (2013).

9. “Lunar Sourcebook: A User’s Guide to the Moon” edited by Grant H. Heiken, David Vaniman,and Bevan M. French ©1991, Cambridge University Press ­ Digital version of the classic 1991publication, a one­volume reference encyclopedia of scientific and technical information aboutthe Moon.

10. “Stratigraphy and Composition of Nectaris Basin Deposits” by Paul D. Spudis and M.CSmith, Lunar and Planetary Institute, Department of Earth and Planetary Sciences, Universityof Tennessee, 44th Lunar and Planetary Science Conference (2013).

11. “On the Age of the Nectaris Basin” by R. L. Korotev, J. J. Gillis, L. A. Haskin, and B. L. Jolliff,Department of Earth and Planetary Sciences, Washington University, Saint Louis MO,Workshop on Moon Beyond 2002

12. “Nectaris Basin Ejecta From Clementine Data” by D. Ben. J. Bussey, Paul D. Spudis, B. RayHawke, Paul G. Lucey, and Dave Blewett, Lunar and Planetary Institute, Houston TX ,University of Hawaii, Honolulu HI, 60th Annual Meteoritical Society Meeting.

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13. “What is the Age of the Nectaris Basin? New Re­Os Constraints for a Pre­4.0 GaBombardment History of the Moon” by M. Fischer­Godde and H. Becker, Institut furGeologische Wissenschaften, FR Geochemie, Freie Universitat Berlin, Germany, Institut furPlanetologie, Westfalische Wilhelms­ Universitat Munster, Germany, 42nd Lunar andPlanetary Science Conference (2011)

14. “Composition of the impact melt sheets of the Orientale and Nectaris impact basins” by PaulD. Spudis, Lunar and Planetary Institute, Houston TX, EPSC Abstracts Vol. 8, EPSC2013­758,2013 European Planetary Science Congress Copyright 2013 Author(s).

15. “Remote Sensing Studies of Geologic Units in the Eastern Nectaris Region of the Moon” by B.R. Hawke, C. R. Coombs, L. R. Gaddis, P. G. Lucey, C. A. Peterson, M. S. Robinson, G. A.Smith and P. D. Spudis. Planetary Geosciences, HIGP, Univ. of Hawaii, Honolulu, HI, College

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