Field trip leaders Thom Davis, Thomas L. Davis Consulting Geologist, Ventura, CA, and

the Geologic Maps Foundation, Inc. Yannick Wirtz, Department of Geological Sciences

California State University Long Beach

Geologic field trip to the Mojave National Preserve, California October 5-7, 2016

PS-RMS AAPG Field trip #5

Geologic field trip to the Mojave National Preserve California, October 5-7, 2016

Pacific and Rocky Mountains Sections of the American Association of Petroleum Geologists (AAPG)

2016 Annual Meeting, Las Vegas, Nevada Field trip #5

Field trip contacts: Thom Davis* and Yannick Wirtz** * www.thomasldavisgeologist.com; www.geologicmapsfoundation.org email: davnamthom@aol.com **email: y.wirtz@gmail.com Coordinator: Dan Sturmer (sturmer.dan@gmail.com ). Meeting Point (35.441001°,-115.673135°): The group will meet at 2:00 pm, 10/5 at the Cima Road exit (also Excelsior Mine Road) off I-15; this exit is about 25 miles from Primm that’s at the Nevada/California border, and Primm is about 40 miles south of Las Vegas. Late arrivals can meet the group at the Mid Hills Campground (35.133237°,-115.434817°) in the Mojave National Preserve (MNP). Yes, this is a change from the original posted time and meeting place and campground. Please top-off your vehicle’s gas tank at the station at the Cima Road exit. There are no gas stations or stores within the MNP, we will be doing a fair amount of driving within the MNP (200-250 miles), and the trip ends near I-40 and there the nearest gas station is about one hour drive. In addition make sure you have food for 2.5 days camping and hiking; water is available at the campgrounds.

End of the trip: The trip will end at 4:00 PM (10/7) at the intersection of the Essex Road and I-40. The field trip does not return to Las Vegas, and from the intersection it’s 1.5 hours drive to Barstow and I-15, and it’s about a 4 hours drive to Los Angeles from the intersection. If you wish to return to Las Vegas then take 1-40 west to Kelbaker Road, go north (right) on that road to Kelso, take the Kelso-Cima Road to Cima, and take the Cima Road to I-15. Vehicles and camping: Participants must provide their own transportation (high clearance vehicles recommended), all meals (including lunches), and camping gear. Camping the first night is at the Mid Hills Campground (MNP), and we will move to the Hole-in-the-Wall Campground (MNP) for the second night. Both campgrounds have water, fire pits, tables, and bathrooms. Campground costs are included in the field trip fee. Trip summary: This will be “very old school” geology where we will hike to the best outcrops and panoramic view locations. Moderate to good level hiking ability is required of the participants (5-7 miles per hike, with about 1,000 feet elevation gains). We will use published geologic maps and our own observational skills to discuss the principal geologic units of the area (Proterozoic gneissic terrane, Paleozoic strata, Jurassic and Cretaceous granitic plutons, Miocene ash and flow deposits, and Quaternary land forms

and deposits), the principal faults and folds, Mesozoic structural events, and the geologic and tectonic history of the Cima Dome, Mescal Range, Ivanpah Mountains, Mid-Hills, Hole-in-the-Wall area, and the Providence Mountains.

Weather and clothing: For this time of year it will be, most likely, warm by midday (upper 80s to lower 90s) but it can be very cool at night (into the 30s or 40s). Mid Hills campground is at 4400 ft and the Hole-in-the-Wall campground is at 5600 ft. This area can be windy too. Please check the weather forecast before the trip and bring what you need to be comfortable. Bring sunscreen, a hat, and sunglasses. Long pants and long sleeve shirts are best to avoid too much sunshine and the numerous plants that will stick you. Recommended for camping and hiking: This is classic car camping so bring firewood, stove, lantern, flashlight, tent (optional), sleeping bags, coolers (with your favorite beverages inside), cooking gear and eating utensils, and food for 2 dinners, 2 breakfasts, and 2 lunches. For hiking bring canteens (several), leather boots or scree gators are recommended, windbreaker, and a day pack to carry your lunch. Note: alcoholic beverages can only be consumed in the campgrounds and after the day portion of the trip is completed. Food and Beverages: Snacks and nonalcoholic refreshments will be provided on the trip, but not meals. Guidebook: Paper copies will be provided at the meet-up area. Emergency: Should an emergency occur, inform the leaders immediately. They will coordinate a response to the appropriate authorities, if needed. If you have a medical condition that should be known, please tell us in advance! Be sure to bring all necessary medications. Liability Waiver: Due to insurance requirements, you must sign the liability waivers before the trip. Please return the Pacific Section and Rocky Mountain Sections of the American Association of Petroleum Geologists (“AAPG PS-RMS ”) liability waivers to Dan Sturmer via email and cc me. If you do not sign the waivers, you will not be allowed to go on the trip.

Geologic information on the MNP: A large amount of information and data about the geology of the Mojave National Preserve are available at various web sites: https://www.nps.gov/moja/index.htm https://www.nature.nps.gov/geology/usgsnps/mojave/mojave1.html http://digital-desert.com/mojave-preserve/geology/10.html https://pubs.usgs.gov/bul/b2160/ http://pubs.usgs.gov/bul/1712d/report.pdf https://pubs.er.usgs.gov/publication/pp275

Regional tectonic map showing the Mojave National Preserve (MNP); formerly the East Mojave National Scenic Area (from USGS Bulletin 2160). Note the eastern limits of various rock provinces and the abundance of east vergent thrust faults.

1st Day (Wednesday, October 5, 2016) From meet-up location drive 11.3 miles south along the Cima Road to Stop 1. Please fill-up your vehicles with gas before leaving the meet-up location.

Stop 1, Teutonia Peak view stop and Cima Dome. View stop from the Cima Road, and depending on the time we will do a 2.5 mile round trip hike to Teutonia Peak area. We need to leave Stop 1 at 4:30 PM in order to be at the Mid-Hills campground by 5:30 PM; sunset is at ~6:30 PM.

Present and discuss:

Regional geology.

Teutonia Peak (elev=5754’) an inselberg above a broad pediment. Peak consists of Jurassic Ivanpah granite while most of Cima Dome consists of Cretaceous Teutonia quartz monzonite (adamellite).

View to the east of Kessler Peak (elev=6163’), Ivanpah Mountains, and New York Mountains; Kessler Peak consists of Jurassic Ivanpah granite.

Late Cretaceous extension and uplift, and the East Mojave fault (Miller, et al, 1996; Wells, et al., 2005).

View to the north of the Shadow Valley, Clark Mountain, and the Kingston Range; east vergent Clark Mountain thrust complex (Nelson and Burchfiel, 1979).

View to the west of the Cima Dome, and beyond the Cinder Cone Lava Beds.

View to the south of the Providence, Granite and Kelso Mountains, and Kelso Dunes.

Cima Dome and pediment formation: A pediment is a gently sloping erosion

surface or plain of low relief formed by running water in arid or semiarid region at the base of a receding mountain front. A pediment is underlain by bedrock that is typically covered by a thin, discontinuous veneer of soil and alluvium derived from upland areas. Much of this alluvial material is in transit across the surface, moving

during episodic storm events or blown by wind. Pediment-forming processes are much-debated, but it is clear that rocks such as granite and coarse sandstone (and Tertiary conglomerate made up of boulders of these rocks) form virtually all pediments in the Mojave Desert. These rocks disintegrate grain-by-grain, rather than fracturing and then being reduced in grain size by alluvial transport processes. Large areas within the Mojave Desert are pediment surfaces. These pediments reflect both the antiquity of some mountain structures in the region and the persistent arid climatic conditions in the region. Perhaps the most notable pediment in the region is Cima Dome, a very broad, shield-shaped upland area within the Mojave National Preserve (below). This great, gently-sloped upland area represent a region where desert-style weathering and erosion has stripped away most of the relief to the point that the erosion keeps pace with surface weathering and that surface gradient is gentle enough to prevent gully-style downcutting. Isolated rocky hills or knobs that rise abruptly from an erosional surface in desert regions are called inselbergs. The development of pediments and alluvial fans is progressive with the uplift of mountains and subsidence of adjacent basins. Pediments reflect a relative "static equilibrium" between erosion of materials from upland areas and deposition within an adjacent basin. The slope of the landscape is gentle enough that weathering and transport of sediments from upland areas and the pediment that no significant stream incision occurs. In many areas throughout the Mojave region it is nearly impossible to see where a pediment ends and alluvial fans begin, however, geophysical data and water-well drilling shows that in many places sediment filled basins do occur adjacent to pediment areas.

The impact of climate change on alluvial fans has been the focus of much research. Studies show that a period of elevated alluvial fan deposition occurred between the time of the Last Glacial Maximum (about 15,000 years ago) and the beginning of arid conditions in the early Holocene (about 9,400 years ago). McDonald et al, (2003) suggest that the climatic transition from seasonable wet conditions to arid conditions, punctuated by extreme storm event (possibly associated with tropical cyclones) may be responsible for this change. Today, heavy rainfalls rarely provide enough precipitation to allow enough surface runoff to occur on highly porous soils and colluvium. Only during major stream event will water discharge in volume and intensity to move material from mountain source areas to lower fan areas. In addition to extreme storm events, the buildup of alluvial fan deposits at this Pleistocene/Holocene time transition may be linked with the transition from widespread plant cover to the more barren character of the modern Mojave landscape. Die-back of plants would decrease rooting, making more mountain-side material available for erosion and transport to alluvial fans.

The full version of the above discussion on pediments, with photos, can be found at http://digital-desert.com/mojave-preserve/geology/10.html

From USGS Bulletin 2160.

Cima Dome from the Mid Hills. Teutonia Peak is barely visible just

right of the crest of the Dome, and the Ivanpah Mountains are just

right of the Peak.

Teutonia Peak, an inselberg of Jurassic Ivanpah granite.

From: USGS Geology in the Parks, MESOZOIC ROCKS, by Gordon B. Haxel and

David M. Miller, http://geomaps.wr.usgs.gov/parks/mojave/MESOmoja.html

Jurassic Plutonic Rocks: The Ivanpah Granite of Beckerman and others

(1982) is 150 to 145 Ma (J.D. Walker, 1992, oral commun.). It consists of biotite monzogranite that is strongly porphyritic. The pluton is moderately

peraluminous and potassic.

Cretaceous Plutonic Rocks: Most Cretaceous plutonic rocks of the EMNSA

belong to the Early and Late Cretaceous Teutonia batholith (Beckerman and others, 1982Preliminary U-Pb zircon ages for major plutons of the batholith

range from 93 to 100 Ma (determined by E. DeWitt, 1990). The six major plutons that constitute the eastern Teutonia batholith crop out chiefly in the

New York Mountains, Mid Hills, and the Cima Dome-Wildcat Butte-Marl Mountains area (pl. 1). Five of the six plutons are fairly large, with exposed

areas §50 to 200 km2. These plutons are intermediate to felsic in composition. The sixth, mafic pluton forms a subcircular outcrop area §2 km

in diameter; correlative bodies are yet smaller. The five relatively large plutons of the Teutonia batholith principally range in composition from

quartz monzodiorite to syenogranite, with granodiorite and monzogranite as the principal compositional types; monzodiorite is a minor phase of one

pluton. Despite this compositional range, granite constitutes most of the exposed rock. Three of the five plutons are leucocratic--Teutonia Adamellite,

Mid Hills Adamellite, and Kessler Springs Adamellite of Beckerman and

others (1982).

The full version of the below discussion on Mesozoic deformation, with citations, can be found at http://digital-desert.com/geology/mesozoic/07.html Some Mesozoic deformational features of regional extent crop out in the western and north-central parts of the EMNSA. These deformational features are reflections of shortening shown by brittle-style thrust plates developed in the foreland of the Cordilleran thrust belt and ductile-style nappes in southeastern California and Arizona (Burchfiel and Davis, 1971, 1977, 1981; Howard and others, 1980; Snoke and Miller, 1988; Miller and Barton, 1990). Generally east-directed thrust faults, present in the Cowhole Mountains and the Clark Mountain Range areas, may be Middle Triassic(?) through Early Jurassic (Burchfiel and Davis, 1981).

From Stop 1 drive 6 miles south to the road intersection at Cima and take the Kelso-Cima Road south 5 miles. Turn left on to the Mojave Road and continue 6 miles east on the Mojave Road. Turn right on to the Black Canyon Road and from there go 3 miles south. Make a right on to the Wild Horse Canyon Road and follow for 2 miles to the entrance to the Mid-Hills Campground. We will camp the first night at Mid Hills.

Portion of the geologic map from USGS Bulletin 2160 showing the Mid Hills. The East Providence fault (Hazzard, 1954) is now considered a segment of the regional East Mojave fault (Miller, et al., 1996; Wells, et al., 2005).

A Mid Hills Campground site.

2d Day (Thursday, October 6, 2016) We will depart Mid-Hills campground by 7:30 AM; sunrise is ~6:30 AM. From Mid Hills Campground return to Cima via same road we used yesterday. From Cima take the Cima Road 10.5 miles north to a dirt road, turn off on the right, and head 2.0 miles east to reach the south side of Striped Mountain.

Map showing various roads in the Ivanpah Mountains and Mescal Range (from Digonnet, 2013).

Stop 2, Striped Mountain loop and hike. We will investigate the

geology around Striped Mountain (elev=5954’), the west flank of the Ivanpah Mountains, and south side of the Mescal Range. This will require a driving loop around the mountain and taking short hikes to key locations. Present and discuss:

Mesozoic deformation: Structural elements from Sevier and Laramide events are present in this area (Nelson and Burchfiel, 1979).

Late Cretaceous deformation (Laramide) in the southern Cordillera was different from the northern segment as it is now believed that it was affected primarily by extensional, and possibly strike-slip deformational events (Burchfiel, et al., 1992).

Early Cretaceous thrust faults in the Clark and New York Mountains may have several tens of kilometers of eastward directed overthrusting with some of the thrusts having hanging-walls of crystalline basement and the convergent structures may represent the southernmost extent of the Sevier event (Burchfiel, et al., 1992).

Striped Mountain, Ivanpah Mountains.

Cross section I-I’ from USGS Professional Paper 275 showing a portion of the east vergent Clark Mountain thrust complex (Nelson and Burchfiel, 1979).

A portion of the geologic map from USGS Professional Paper 275 (Hewett,

1956) showing Cima Dome, Ivanpah Mountains, and Mescal Range. The

Clark Mountain fault is now called the Kokoweef fault (Nelson and Burchfiel,

1979). The Mescal fault is part of the Clark Mtn. thrust complex.

The East Mojave fault (EMF) is a proposed regional structure that

combines several previously mapped faults (East Providence fault, Pinto

shear zone of the New York Mountains, and Cima faults) (Miller, et al.,

1996). The EMF has down on the west separation and is offset by Miocene

and younger faults. During the late Cretaceous the EMF connected areas

of extension from Death Valley southward to the Old Woman Mountains

and provide further support for regional extension in the North American

Cordillera at about 70 Ma. Mapping suggests that the Kokoweef fault might

be another splay of the EMF.

Portion of the geologic map from USGS Bulletin 2160 showing the Ivanpah

Mountains and southern Mescal Range. Note the numerous east vergent

thrust faults. South of the red boundary is Mojave National Preserve

(MNP) land. See the end of this guidebook for the map explanation.

We will depart the Striped Mountain area about noon and return to the Cima Road via the Zinc Mine Road. Then take the Cima Road left (south) to Cima and turn left on the Morning Star Mine Road. From there go 11 miles north to the Mine Cutoff Road, turn left, and go about 3 miles west into the east flank of the Ivanpah Mountains.

Stop 3, New Trail Canyon and Oro Wash area The second half of Day 2 we will explore the geology and hike along the east flank of the Ivanpah Range. Present and discuss:

Oro Wash and New Trail Canyon mining area.

Kokoweef syncline and deformation of the crystalline basement and overlying strata (Nelson and Burchfiel, 1979).

Portion of the geologic map from USGS Bulletin 2160 showing the New

Trail Canyon mining area. The Kokoweef syncline is shown in the

upper left corner of the map. Nelson and Burchfield (1979) provide a

more detailed map of the syncline and discussion of its deformational

style.

We will depart the Ivanpah Mountains by 4:00 PM. We will follow the route we took yesterday towards the Mid Hills Campground. However, from the Mojave Road we will turn right (south) and continue 10 mile south to the Hole-in-the-Wall Campground for our second night in the field.

Hole-in-the-Wall Campground from the east side of Barber Peak.

Barber Peak from the Hole-in-the-Wall Campground.

3d Day (Friday, October 7, 2016) We will hike out of the Hole-in-the-Wall Campground by 7:30 AM; sunrise is at ~6:30 AM. We will either hike to the top of Barber Peak or make the Barber Peak loop trail followed by a hike to the Hole-in-the-Wall.

Stop 4, Barber Peak, Wild Horse Mesa, and the Woods Mountains. Present and discuss:

Miocene Woods Mountains igneous source and sequence (a rhyolite flow and dome phase followed by an explosive phase of ash and lava flows, and followed by caldera collapse and infilling)(McCurry, 1988).

Local Miocene igneous stratigraphy (see below map): Tdf=rhyodacite flows and domes, Tw=Wild Horse Mesa Tuff, Tts=Tortoise Shell Mountain Rhyolite, Tb=basalt flows.

Portion of the geologic map from USGS Bulletin 2160 showing the Hole-in-the-Wall area, Wild Horse Mesa, and Woods Mountains.

We will depart the Hole-in-the-Wall Campground by noon and drive to the Bonanza King mine in the northeastern Providence Mountains. From the Hole-in-the-Wall Campground take the Black Canyon Road 10.5 miles south to the Essex Road and turn right (west). Take the Essex Road for about a mile to the “Ranch Road,” then turn right and go north for about 6 miles; turn left on the road to the Bonanza King Mine that is about 3 miles further west.

Stop 5, Bonanza King Mine and Providence Mountains Present and discuss:

Structure of the Providence Mountains and the East Providence fault.

Bird Springs Formation and late Paleozoic paleogeography (Stevens and Stone, 2007).

Cenozoic events: Basin and Range extension, Peach Springs Tuff.

Bonanza King Mine: East Mojave’s second richest silver mine.

Portion of the geologic map from USGS Bulletin 2160 showing the Providence Mountains.

Portion of the geologic map from USGS Bulletin 2160 showing the Bonanza King Mine area in the northern Providence Mountains.

One of the many openings at the Bonanza King mine, northern Providence Mountains.

End of the field trip at the junction of Black Canyon Road and Essex Road. Exit (MNDP) and connect with I-40 via the Essex Road.

Citations and key sources of information

Burchfiel, B.C., Cowan, D.S., and Davis, G.A., Tectonic overview of the Cordilleran orogeny in the western United States, in Burchfiel, B.C., Lipman, P.W., and Zoback, M.L., "The Cordilleran Orogen: Conterminous US," Geological Society of America, Vol. G-3, 1992, Chapter 8, pp. 407-480. Digonnet, M., 2013, Hiking the Mojave Desert: Natural and cultural heritage of Mojave National Preserve, Publisher’s Cataloging-in-Publication (Provided by Quality Books, Inc.), Palo Alto, CA, ISBN: 978-0-9659178-2-7, 452 p. Goldfarb, et al, 1987, Mineral Resources of the Providence Mtns, USGS Bulletin 1712-D: D1-D70. Hazzard, J.C., 1954, Rocks and structure of the northern Providence Mountains, San Bernardino County, CA, in R.H. Jahns ed., Geology of southern California, Chpt IV, California Division of Mines, Bulletin 170, p. 27-35. Hewett, D.F., 1956, Geology and Mineral Resources of the Ivanpah Quad, USGS Professional Paper 275, 172 p. McCurry, M.O., 1988, Geology and petrology of the Woods Mountains volcanic center, southeastern California—Implications for the genesis of peralkaline rhyolite ash flow tuffs: Journal of Geophysical Research, v. 93, no. B12, p. 14,835–14,855. Miller, D.M., 1994, Field guide to the Proterozoic Geology of the New York, Ivanpah, and Providence Mtns, USGS Open-file report 94-674.

Miller, D.M., Wells, M.L., Dewitt, E., Walker, J.D., and Nakata, J.K., 1996, Late Cretaceous extensional fault system across the northeastern Mojave Desert, in Reynolds, R.E., and Reynolds, J., compilers, Punctuated chaos in the northeastern Mojave Desert: San Bernardino County Museum Quarterly, v. 43, no. 1/2, p. 77-84.

Nelson, E.P. and Burchfiel, B.C., 1979, Deformation of autochthonous foreland basement, Clark Mountain thrust complex, southeastern California, in G.W. Newman and H.D. Goode, eds, Basin and Range Symposium and Great Basin Field Conference, Rocky Mountain Association of Geologists and Utah Geological Association, p.107-114.

Stevens, C.H. and Stone, P., 2007, The Pennsylvanian-Early Permian Bird Spring carbonate shelf, southeastern California: Fusulinid biostratigraphy, paleogeographic evolution, and tectonic implications, Geologic Society of America Special Paper 429, 82 p.. Theodore, T.G., 2007, Geology and Mineral Resources of the Eastern Mojave National Scenic Area, USGS Bull 2160.

Wells, M.L., Beyene, M.A., Spell, T.L., Kula, J.L., Miller, D.M., and Zanetti, K.A., 2005, The Pinto shear zone; a Laramide synconvergent extensional shear zone in the Mojave Desert region of the southwestern United States: Journal of Structural Geology, v. 27, p. 1697-1720.

East dipping beds of the Mississippian Monte Cristo limestone, northeastern Providence Mountains.

Wild Horse Mesa viewed from near the Bonanza King Mine, northeastern Providence Mountains.

Edgar Peak (right) and Fountain Peak (left) viewed from the east flank of the Providence Mountains.