Stratigraphy Commons^™

Analysis Of Cryptotephra At Whitney Mesa Nature Preserve, Henderson, Nevada, Alex Newsom

Calvert Undergraduate Research Awards

Advanced Undergraduate Winner

Cryptotephra (small volcanic shards ranging 20-80 microns in size) were discovered within Unit X of the Las Vegas Formation at Whitney Mesa Nature Preserve, Henderson, Nevada. Cryptotephra are deposited soon after a volcanic eruption and can be used as a dating tool to create narrow time constraints for surrounding sediments. Cryptotephra have many applications but are mainly useful as a dating tool. Their study has important implications for the understanding of the timing of palaeoclimatological and paleoenvironmental events as well as for archaeological studies to date important events in human history.

The Whitney Mesa cryptotephra were correlated …

Chemostratigraphic Correlations Across The First Major Trilobite Extinction And Faunal Turnovers Between Laurentia And South China, Jih-Pai Lin, Frederick A. Sunberg, Ganqing Jiang, Isabel P. Montanez, Thomas Wotte

Geoscience Faculty Research

During Cambrian Stage 4 (~514 Ma) the oceans were widely populated with endemic trilobites and three major faunas can be distinguished: olenellids, redlichiids, and paradoxidids. The lower–middle Cambrian boundary in Laurentia was based on the first major trilobite extinction event that is known as the Olenellid Biomere boundary. However, international correlation across this boundary (the Cambrian Series 2–Series 3 boundary) has been a challenge since the formal proposal of a four-series subdivision of the Cambrian System in 2005. Recently, the base of the international Cambrian Series 3 and of Stage 5 has been named as the base of the Miaolingian …

Detrital Carbonates In A Sequence Stratigraphic Framework: An Example From The Furongian Slope Environment In The Hot Creek Range Of Central Nevada, Leon Taufani

UNLV Theses, Dissertations, Professional Papers, and Capstones

An integrated sedimentological study of detrital carbonates of the late Cambrian (Furongian) Hales Limestone in central Nevada was conducted in order to model facies distribution and controlling mechanisms of carbonate gravity-flow deposits. Seven closely-spaced sections and numerous traceable short sections were measured to investigate temporal and spatial changes of detrital carbonates within a high-resolution stratigraphic framework supported by biostratigraphic and carbon isotope chemostratigraphic constraints and by key physical surfaces. Polished slabs and thin section petrographic analysis were used to identify micro- and macro-scale textures and diagenesis.

Ten lithofacies are identified from the Hales Limestone. Lateral tracing of these facies reveals …

Evaluation Of Possible Source Rocks In Northern Nye County, Nevada: Implications For Hydrocarbon Exploration, Inessa Yurchenko

UNLV Theses, Dissertations, Professional Papers, and Capstones

The presence of oil outside of Railroad Valley, northern Nye County has sparked the interest of exploration companies in Nevada. The geology in this region is very complex and the level of petroleum exploration is low. In order to understand the distribution of oil, a complete petroleum systems analysis is required. Previous studies confirmed that the Mississippian Chainman Shale and Cretaceous to Paleocene Sheep Pass Formation, Member B are source rocks. However, a number of other possible source rocks exist in northern Nye County, but they are not confirmed because of incomplete datasets. The goal of this thesis project is …

Burial And Exhumation History Of Mississippian Strata In East-Central Nevada, Yuki Yunika Agulia

UNLV Theses, Dissertations, Professional Papers, and Capstones

Zircon (U-Th)/He analyses and vitrinite reflectance (Ro) analyses were performed on a suite of Mississippian sedimentary rocks collected in east-central Nevada in order to test Permian exhumation described in a previous study.

The zircon analyses produced three clusters of ages: 1) older than, 2) similar to, and 3) younger than depositional age. The majority of zircons shows ages that are older than the sandstone deposition age. Young ages were recorded in three localities that may indicate reset ages/residence within the (U-Th)/He partial retention zone (HePRZ). Moderate-high ratios of Th/U may indicate a magmatic source. Vitrinite reflectance (Ro) analyses show values …

The Effects Of Salt Diapirs On The Thermal Maturity Of Surrounding Sediments In The Western Pyrenees, Spain, Nicholas Martin Downs

UNLV Theses, Dissertations, Professional Papers, and Capstones

Salt diapirs have been modeled as having a large effect on the thermal maturity of surrounding sediments as a result of the high thermal conductivity contrast between halite and other lithologies. The goal of this study was to confirm these and other theoretical predictions through sampling of three salt structures in the western Pyrenees, Spain. Stratigraphic units around these three diapirs were targeted based on their lithologies and positions relative to the diapirs. Samples were analyzed for vitrinite reflectance and quartz cementation to determine their levels of thermal maturity. Remote sensing instruments were used to attempt to measure present day …

Muddy Creek Formation: A Record Of Late Neogene Tectonics And Sedimentation In Southern Nevada, Thomas William Muntean

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Late Neogene Muddy Creek Formation (MCF), exposed in the vicinity of Lake Mead in southern Nevada, represents the youngest widespread Cenozoic sedimentary sequence in the region and is the focus of this study. Historically, the MCF has been largely ignored, with limited previous studies providing only regional-scale constraint on the age, stratigraphy, and mode of deposition for the formation; resulting in a data gap for our understanding of the Late Cenozoic tectonic and sedimentological evolution of southern Nevada.

Paired Positive Carbonate Carbon Isotope, Organic Carbon Isotope, And Oxygen Isotope Composition Study Across The Lower Mississippian Positive Carbon Isotope Excursion, Southeastern Nevada, Usa, Robert Alan Henry

UNLV Theses, Dissertations, Professional Papers, and Capstones

A prominent positive carbonate carbon isotope (delta13Ccarb) excursion of Early Mississippian age (ca 351 Ma) has been documented by previous studies from numerous sites globally. This delta13Ccarb excursion has been interpreted as resulting from enhanced organic carbon burial that removed 13C-depleted carbon from the ocean and atmosphere. Anticipated outcomes from enhanced organic carbon burial would include a similar positive excursion in organic carbon isotopes (delta13Corg) and a global cooling event resulting from reduced CO2 in the atmosphere and ocean. These predictions, however, were not tested sufficiently in previous studies. This research has tested these predictions through an integrated study of …

Lateral Variability Of Facies And Cycles In The Furongian (Late Cambrian) Carbonate Platform: An Example From The Big Horse Member Of The Orr Formation In Western Utah, U.S.A., Ratna Widiarti

UNLV Theses, Dissertations, Professional Papers, and Capstones

Carbonate depositional cycles and sequences have been proposed to be formed by glacioeustatic sea-level changes. This mechanism would be questionable during times of high atmospheric CO2 and negligible continental ice sheets such as the supergreenhouse time in the Furongian (late Cambrian), during which limited glacioeustatic sea-level changes would be expected. A detailed sedimentological study of the Furongian Orr Formation in western Utah is aimed at testing the hypothesis that, under supergreenhouse climate conditions, most meter-scale carbonate cycles may have been formed through autocyclic processes and thus they should be laterally variable. The research was conducted in a small area ( …

Sequence And Chemostratigraphy Of The Middle Cambrian Succession In Nevada And Utah, Robyn A. Howley

UNLV Theses, Dissertations, Professional Papers, and Capstones

The House Range Embayment of western Utah and eastern Nevada was a prominent topographic feature on the passive margin of western North America during the middle and late Cambrian. In this study, detailed documentation of sequence boundaries, and their intervening sequences across a platform-to-basin transect of the House Range Embayment was used to establish a sequence-stratigraphic framework from which the depositional history of the embayment was deciphered. This framework was then used to test the hypothesis that the House Range Embayment formed by tectonic subsidence. In addition, the chemostratigraphic (δ13Ccarb) record across the embayment was analyzed within this framework to …

Geology Of The Southern Reveille Range, Nye County, Nevada, Matthew Alan Mckelvey

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Reveille Range in central Nevada provides a unique window into the mid-Miocene geology and volcanology of the central Great Basin during the "ignimbrite flare up." Although faulted along its margins, the interior of the range is relatively undeformed thus preserving volcanic centers. The Reveille Range contains three mid-Miocene caldera complexes. Previous studies have identified the Goblin Knobs caldera (25.6 Ma) in the central Reveille Range and the caldera of northern Reveille Range (25.3 Ma) to the north. These calderas are completely filled with intracaldera tuffs. This study has identified a younger third caldera located in the southern part of …

Hydrostratigraphy And Allostratigraphy Of The Cenozoic Alluvium In The Northwestern Part Of Las Vegas Valley, Clark County, Nevada, David J. Donovan

UNLV Theses, Dissertations, Professional Papers, and Capstones

This investigation was conducted to determine the location, nature, and boundaries of the most permeable unit within the alluvial aquifer material in Las Vegas Valley. It was prompted by declines in specific capacity of about 90% at the Las Vegas Valley Water District's West Central Well Field. It was hypothesized that the decline in specific capacity resulted from dewatering of the most permeable interval of the alluvium. Lithologic descriptions from wells and aquifer test information were analyzed for geologic and hydrogeologic variability. New information, in the form of detailed unpublished lithologic and hydrologic information, was available from twenty water wells …

The Geology Of The Tuff Of Bridge Spring: Southern Nevada And Northwestern Arizona, Shirley Ann Morikawa

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Tuff of Bridge Spring (TBS) is a regionally-widespread, andesite to rhyolite (59.50 to 74.91 wt. %) ash-flow tuff of mid-Miocene age (ca. 15.2 Ma) that is exposed in the northern Colorado River extensional corridor of southern Nevada and northwestern Arizona. Determination of the areal distribution, geochronology, lithology, geochemistry, and internal stratigraphy of the TBS is important for its establishment as a reliable stratigraphic reference horizon for tectonic reconstructions of the extensional corridor during the middle Miocene. Based on reoccurring patterns of major and trace element variation, the TBS is divided into constant Cr/variable SiO₂ and variable Cr/variable SiO …

Stromatolites Of The Lower Cambrian Deep Spring Formation; Mount Dunfee, Esmeralda County, Nevada, Lynn Oliver

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Middle Member of the Lower Cambrian Deep Spring Formation at Mount Dunfee, Nevada contains a diverse assemblage of stromatolites that formed on a tide- and storm-dominated, siliciclastic-influenced, carbonate shelf. The stromatolites formed in a shallow subtidal environment within and near active oolite shoals under strongly focused currents. The stromatolites occur in four different lithofacies: (1) bioherms of digitate stromatolites, (2) bioherms and biostromes of inclined stromatolites, (3) isolated forms of massive and hemispheroidal stromatolites, and (4) a biostrome of cryptomicrobial boundstones. The first three lithofacies are interpreted as microbial reefs. They had topographic relief, formed in active agitated waters, …

Provenance And Description Of Landslide Masses, Rainbow Gardens Clark County, Nevada., Joseph R. Parolini

UNLV Theses, Dissertations, Professional Papers, and Capstones

A landslide breccia of plutonic and metamorphic rocks located 20 km east of Las Vegas, Nevada is interstratified with the late Tertiary Thumb Formation. Rock types of similar mineral composition to the landslide masses in the Rainbow Gardens are found 60 km to the east in the Gold Butte (Nevada) area. The landslide masses were displaced into their present position by lateral strike-slip motion along either the left-lateral Lake Mead fault system or the right-lateral Las Vegas shear zone. In t.he Rainbow Gardens landslide masses, five plutonic rock types, including rapakivi granite, match rocks from the Gold Butte area, both …

Geology And Ore Deposits Of The Johnnie District, Nye County, Nevada, Stanley Wayne Ivosevic

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Johnnie district, in the northwestern Spring Mountains, Nye County, Nevada, may have produced a little under 100,000 troy oz of gold, since the discovery of the district in 1890.

An approximately 13,000-ft-thick (4,000 m) section of east-dipping upper Precambrian through Middle Cambrian miogeosynclinal clastic and carbonate rocks is exposed in the district. The strata are, in order of decreasing age, the Johnnie Formation, Stirling Quartzite, Wood Canyon Formation, Zabriskie Quartzite, and Carrara and Bonanza King Formations. These are overlain by Cenozoic units which include and older unit and a younger unit of fanglomerate, the older containing a megabreccia deposit, …

Stratigraphic Comparison Of The Precambrian Wyman And Johnnie Formations In The Western Great Basin, California, Johnnie Nathan Moore

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Precambrian Johnnie Formation in the Death Valley area and to the south is separable into two facies. The southern facies contains six distinct members: the transitional, quartzite, lower carbonate-bearing, siltstone, upper carbonate-bearing, and Rainstorm members. Dolomite, quartzite, and mudstone characterize the southern facies, as does the presence of the Johnnie oolite. To the north the Johnnie oolite pinches out and the amount of mudstone in the formation increases. The dominantly mudstone northern facies contains local gray limestone lenses closely similar to limestone in the Wyman Formation in the White-Inyo Mountains. Generally outcrops of the northern facies of the Johnnie …

Interbasin Movement Of Ground Water At The Nevada Test Site, Isaac J. Winograd

Publications (WR)

The present paper presents hydraulic evidence for the interbasin circulation of ground water through carbonate rocks of Paleozoic age at the Nevada Test Site. An integral part of this evidence is the discovery that aquifers in alluvium and tuff, formerly thought to be the principal aquifers at the Test Site, are semiperched above a thick tuffaceous aquiclude that separates them from the carbonate rocks.

This paper is based on one of the studies being made by the Geological
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