Thesis project information sheet

Project Title Weathering and salt accumulation at Don Juan and Don Quixote ponds in the Antarctic Dry Valleys as an analogue to alteration on Mars

Mentor(s)/Supervisor(s) Peter Englert Affiliation HIGP

Email penglert@hawaii.edu Number 808 384 3500

Project Description We are investigating variations in gypsum and anhydrite abundance with depth and distance from the center of Don Juan and Don Quixote ponds in order to determine if the hydration level of these Ca sulfates can be related to other salt abundances or iron oxide or clay mineralogy. Don Juan and Quixote ponds may be good examples of what to expect in past or present small ponds on Mars.

Desired Skills and Experience

Preferred prerequisites: GG101, or GG105, and CHEM161, MATH241, MATH242, PHYS 272; junior standing

What students will learn

Students can apply technical knowledge of relevant computer applications,

laboratory methods, field methods, and the supporting disciplines to solve real

world problems; students use the scientific method to define, critically analyze,

and solve a problem in earth science; students can evaluate and interpret the

basic principles of Antarctic geology and explain complex phenomena in the

context of Earth & planetary science.

Start Date TBD End date

Minimal Expected Duration

6 months Hours per week 5≤10

Student Support ($) TBD

Project posted on 10-23-2017

Weathering and salt accumulation at Don Juan and Don Quixote ponds in

the Antarctic Dry Valleys as an analogue to alteration on Mars

P. Englert University of Hawaii at Mānoa

J. L. Bishop SETI Institute & NASA Ames Research Center

C. Koeberl University of Vienna & Natural History Museum

Antarctic Dry Valleys

Project tasks:Sample preparationSample analysisData evaluationSynthesis and InterpretationPublication

Weathering and salt accumulation at Don Juan and Don Quixote ponds in

the Antarctic Dry Valleys as an analogue to alteration on Mars

Methods:XRDReflectance SpectroscopyRaman SpectroscopyNeutron Activation AnalysisChemical Analysis

Weathering and salt accumulation at Don Juan and Don Quixote ponds in the Antarctic Dry Valleys as an analogue to alteration on Mars

P. Englert1, J. L. Bishop2, B. Sutter3, E. K. Gibson4 and C. Koeberl5,6

80th Annual Meeting of the Meteoritical Society, July 2017Abstract

The formation of Don Quixote Pond in the North Fork of Wright Valley, Antarctica, and Don Juan Pond in the South Fork are models for unique terrestrial calcium, chlorine, and sulfate weathering, accumulation, and distribution processes [1, 2]. General understanding of the formation of Don Quite Pond by simple shallow and deep groundwater [1] is contrasted for Don Juan Pond by two models that emphasize deep groundwater upwelling [1] and/or seasonal near surface water flows from basement walls and via a water 'thalweg' [3]. In addition to the high abundance of Calcium Chloride [2] our study found that Calcium Sulfates are abundant, showing unique distribution pattern in the pond areas. Our study intends to understand the formation of Don Quixote and Don Juan Ponds as unique terrestrial processes and as models for Ca, Cl, and S weathering and distribution on Mars [3].

Background

➢ Don Quixote Pond (DQP) and Don Juan Pond (DJP) and Basin (DJB) are located in the North Fork and South Fork of Wright Valley, Antarctica, respectively.

➢ The North and South Fork of Wright Valley are unique areas where unusual terrestrial processes can be studied.

➢ DQP is located in the western part of the North Fork of Wright Valley, Antarctica, about 100 m above Mean Seawater Level. Unlike DJP, the DQP brine is seasonally frozen [1]. Valley walls are up to 2500 m high.

➢ DJP, the center of DJB is located about 9 km West of Lake Vanda. The basin floor is 117m above Mean Seawater Level with activity to the north and south rising above 1000 m.

➢ Dickson et al. 2013 [3] characterized DJB as a model environment for calcium and chlorine weathering and distribution on Mars. We agree with this assessment.

Fig. 1. Antarctic Dry Valley research sites Fig. 2. Don Quixote and Don Juan Pond sites.

Don Juan Pond

1200 m East

4300 m East

➢Sample locations East of Core 2074 go to a distance of about 4.3 km, and West of Core 2074 to distances of of about 150 m and 300 m.

➢Potential drainage divides East of DJP and a depression at VXE-6 Basin may have influenced pathways of surface water and the nature of alteration products.

➢Divides between Core 21 and 37, [3], and adjacent to cores 52 and 38, [4], are at 2 km and 4.3 km East, the latter at an altitude of about 200 m, i.e. about 80 m above pond level.

➢Maximum sampling core length of 6 cm to 31 cm reflects the depth of the permafrost.

Don Quixote Pond

Fig. 4. Don Quixote Pond Sampling Locations

➢ A field photograph with overlaid drawing shows surface sampling locations and five zones of discoloration which become lighter in color with distance from the center of the pond. (Fig. 4).

➢ Three sediment cores, 20,35, and 41 and samples of local rocks were collected.➢ A set of radial surface samples, JB 1146-51 and 1156 a&b, with distances of 14.5 m to over 43.5

m from the pond center were collected.

ResultsSamples were collected from surface, soil pits and depth profiles during the 1979/1980 season, the 1990/1991 and the 2005/2006 field seasons. The several sets of sediment and soil samples from the North and South Fork of Wright Valley were analyzed by INAA, XRD, reflectance spectroscopy, Raman spectroscopy, total C & S, S-isotopes (very few samples), other geochemical analysis methods, e.g. Gibson et al. 1983; Bishop et al. 2001; Englert et al. 2012, Bishop et al. 2014 [4-7]. Similar extensive work has been completed in Taylor Valley by J.D. Toner(2012) [8], and Toner et al. (2013) [9].

Halite, Sulfates and Salts in Don Quixote Pond Color Zone Surface Samples

Fig. 5. Halite, Gypsum and Anhydrite by Color Zone

➢ The two samples from color zone 1, JB1157 and JB1158, are fragile evaporites.➢ There is only one sample from color zone 2, JB1146, at a distance of 14.5 m from the pond

center.➢ JB1147,48, and 49 in color zone 3, are at distances of 16.5, 20.5, and 28.5 m along a radial

sampling traverse to the South.➢ Color zone 3 radial traverse samples show consistently high abundances of Halite and sulfates,

Fig. 7. Otherwise, low concentrations of sulfates are present in all locations, with occasional occurrences of Halite.

➢ In color zone 4 JB1150 is at 33.5 m along the traverse, while JB1155 and JB1152 are southeast and east of Core 48 at distances of 23 m each, respectively. JB1153 and JB 1154, at a distance of 27.5 m, belong also to zone 4.

➢ Color zone 5 covers the remaining area with JB 1151 (43.5 m distance), 1156 a&b, and JB1159 as representative samples, several pond diameters out.

Halite, Sulfates and Salts in Don Quixote Pond Color Zone Surface Samples

Fig. 6. Salt Abundance by Color Zone. Color zone 3 samples show the highest salt load.

➢Color zone 3 samples also show the highest salt load (Salts include small amounts of Thenardite and Bassanite found occasionally), Fig. 6

Halite and Sulfates in Don Juan Basin Surface and Depth Profile Samples

Fig. 7. Sulfates in Depth Profile Samples of Don Juan Basin and Don Juan Pond

➢ Almost all depth profile and surface samples of Don Juan Basin show sulfates including Thernardite, Anhydrite, Bassanite and Gypsum. Gypsum and Anhydrite dominate, Fig. 7.

➢ Core 2074 has the highest Sulfate abundances followed by Core 42, Cores 52 and 33, and with Core 39 having the lowest overall abundance, Fig. 7.

➢ Anhydrite clearly dominates the chemically most altered Core 2074. Anhydrite is also most abundant in Core 33, which is very close to Don Juan Pond and Core 2074.

➢ Anhydrite is on average equally abundant to Gypsum in Core 42, the second most altered Core, although abundance ratios vary with depth. Core 52 Drive Core and Pit

Soil Pit

Drive Core

Fig. 8. Core-Pit relation

➢ Core 39 is low in both Anhydrite and Gypsum.➢ Only in Core 52 does Gypsum have a significantly

higher abundance than Anhydrite, with no Anhydrite present at greater depth.

➢ The highest Gypsum concentration in Core 52 is found at about 6 cm depth, in line with the white horizon in the field photograph, Fig. 8.

➢ High Sulfate and low Quartz abundances in Cores 2074 and 42 are indicators of significant chemical and physical alteration.

Fig. 9. Distribution of Surface Salts as a function of distance from DJP and DQP

AcknowledgementsWe are grateful to the SETI Institute for its continuous support. Thanks are also due to T. Hiroi for acquiring the spectra at RELAB/Brown Univ.

Author Affiliation1University of Hawaii at Mānoa, Honolulu, HI, USA, (penglert@hawaii.edu). 2Carl Sagan Center, SETI Institute, Mountainview, CA, USA. 3Jacobs Technology at NASA JSC, Houston, TX, USA. 4NASA Johnson Space Center, Houston, TX, USA. 5,6Natural History Museum & University of Vienna, Vienna, Austria.

Reflectance Spectra

Figure 11. Reflectance Spectra of DQP Core 35 depth profile

Figure 12. Reflectance Spectra of DQP Radial Sampling Traverse

➢ Reflectance spectra of Cores 2074 confirm the presence of Quartz and Gypsum and the high abundance of Anhydrite, Fig. 10. They also show the presence of Calcite and hydrated ferric oxide.

➢ Reflectance spectra of Don Quixote Pond Core 35 and radial traverse samples show hydration bands, probably correlated to high salt abundance. The presence of Gypsum is also confirmed for most samples. The spectra also indicate Calcite and Al-rich phyllosilicates.

➢ Reflectance Spectra of the Core 35 depth profile, Fig. 11, show mineralogical differences with depth including variations in the abundance of quartz, pyroxene and hydrated components. Dashed lines near 4.5 and 4.7 µm mark anhydrite bands and the line at 0.98 µm is due to Fe2+ in pyroxene. Weak bands consistent with Fe/Mg-phyllosilicates are present near 1.4, 1.9, and 2.35 µm.

➢ Reflectance Spectra of samples from a Radial Traverse, Fig. 12, extending outward from Don Quixote Pond exhibit strong H

2O bands near 1.95 and 2.9 µm attributed to hydrated materials. Anhydrite bands are observed near 4.5

µm.

Figure 10. Reflectance Spectra of Don Juan Basin Samples, Core 2074

Discussion & ConclusionsDon Quixote Pond has generally high abundances of halite with gypsum and anhydrite present as the major sulfates. We are investigating variations in gypsum and anhydrite abundance with depth and distance from the center of the pond in order to determine if the hydration level of these Ca sulfates can be related to other salt abundances or iron oxide or clay mineralogy. Color zones are not correlated to salt abundances except for Color Zone 3, which has 15% salts of varying composition in all samples. All sediments also contain quartz, pyroxene and feldspar as observed in other studies [e.g. 5]. Further research may provide an explanation for the well-defined color zones. Don Juan and Quixote ponds may well be a good examples of what to expect in past or present small ponds on Mars.

References[1] Harris H.J.H. & Cartwright K., 1981, in: Dry Valley Drilling Project, L.D. McGinnis, ed., Antarctic Research Series, 33, 193-214. [2] Torii T. & Yamagata J. (1981) Dry Valley Drilling Project 33, 141-157. [3] Dickson J. L. et al., 2013, Sci. Rep. 3: 1166. [4] Gibson E. K. et al., 1983, Journal of Geophysical Research, 88, A912-A928. [5] Bishop J. L. et al. (2001) GCA 65: 2875-2897. [6] Englert P. et al. (2012) 43rd LPSC abs. #1743. [7] Bishop et al. (2014) Phil. Trans. R. Soc. A 2014 372, 20140198. [8] Toner J.D. (2012) PhD Dissertation, University of Washington. [9 ]Toner J.D. et al. (2013) Geochimica et Cosmochimica Acta 110, 84-105.

Fig. 3. Don Juan Basin and Pond Core Sampling Locations

Halite and Sulfates in Don Juan Basin Surface and Depth Profile Samples

➢ Halite is not very abundant in Don Juan basin samples. It is present at levels of 2% or less in very few samples. It is not present in any depth profile samples except for Core 39 where abundance is 2.9% at a depth of 3 cm.

➢Don Juan Pond and Don Quixote Pond have formed in similar climatic and geological environments. Don Juan Basin shows low surface abundances of Halite and relatively high abundances of sulfates throughout with gypsum or anhydrite dominating at different locations, Fig.15. The DQP area, much smaller that DJB, has high surface abundances of Halite with Gypsum present as the major sulfate. This supports that DJP and DQP had different formation conditions.

➢The importance of surface water or groundwater contributions to DJP formation has been raised. Our results can support both mechanisms, but would seek to constrain surface water contributions to a small area.