Earth Sciences Commons^™

Antler Foreland Basin Evolution Recorded In Detrital Zircon U-Pb Geochronology, James Duncan

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Antler orogeny was a Devonian-Mississippian (375-320 Ma) mountain building event that occurred along the western Laurentian margin. The initiation of the Antler orogeny is marked by the emplacement of the Roberts Mountain Allochthon (RMA) that thrust Cambrian-Devonian deep water marine siliciclastic rocks 100 km eastward onto the western Laurentian margin. Shortening related to the Antler orogeny deformed RMA strata and caused a flexural response in the continental crust that resulted in the formation of the adjacent Antler Foreland basin. The paleogeographic history of the RMA strata and tectonic drivers for the Antler orogeny are still debated. Proposed models suggest …

Tectonic Evolution Of The Tucki Mountain Metamorphic Core Complex, Southeastern California: Evidence For Late Cretaceous Extension Within The Sevier-Laramide Orogen, William Killey Barba

UNLV Theses, Dissertations, Professional Papers, and Capstones

The exhumation of Cordilleran metamorphic core complexes from mid-crustal depths in the western U.S. Basin and Range Province has been classically associated with Cenozoic extension. However, recent studies reveal that extensional tectonic exhumation of numerous metamorphic core complexes initiated during the Late Cretaceous. New geologic mapping and structural analysis integrated with geochronology and thermochronology data provide evidence for a Late Cretaceous extensional shear zone, previously interpreted as Miocene in age, within the Tucki Mountain metamorphic core complex on the western flank of Death Valley, California. The shear zone occurs within the immediate footwall of the Miocene-Pliocene Tucki Mountain detachment fault …

Neogene Retroarc Foreland Basin Evolution, Sediment Provenance, And Magmatism In Response To Flat Slab Subduction, Western Argentina, Tomas N. Capaldi, Brian K. Horton, N. Ryan Mckenzie, Chelsea Mackaman-Lofland, Daniel F. Stockli, Gustavo Ortiz, Patricia Alvarado

Geoscience Faculty Research

Understanding the effects of flat slab subduction on mountain building, arc magmatism, and basin evolution is fundamental to convergent‐margin tectonics, with implications for potential feedbacks among geodynamic, magmatic, and surface processes. New stratigraphic and geochronological constraints on Cenozoic sedimentation and magmatism in the southern Central Andes of Argentina (31°S) reveal shifts in volcanism, foreland/hinterland basin development, sediment accumulation, and provenance as the retroarc region was structurally partitioned during slab flattening. Detrital zircon U‐Pb age distributions from the western (Calingasta basin), central (Talacasto and Albarracín basins), and eastern (Bermejo foreland basin) segments of the retroarc basin system preserve syndepositional volcanism and …

Fault Slip And Exhumation History Of The Willard Thrust Sheet, Sevier Fold‐Thrust Belt, Utah: Relations To Wedge Propagation, Hinterland Uplift, And Foreland Basin Sedimentation, W. A. Yonkee, Bryan Eleogram, Michael L. Wells, Daniel F. Stockli, Shari Kelley, D. E. Barber

Geoscience Faculty Research

Zircon (U‐Th)/He (ZHe) and zircon fission track thermochronometric data for 47 samples spanning the areally extensive Willard thrust sheet within the western part of the Sevier fold‐thrust belt record enhanced cooling and exhumation during major thrust slip spanning approximately 125–90 Ma. ZHe and zircon fission track age‐paleodepth patterns along structural transects and age‐distance relations along stratigraphic‐parallel traverses, combined with thermo‐kinematic modeling, constrain the fault slip history, with estimated slip rates of ~1 km/Myr from 125 to 105 Ma, increasing to ~3 km/Myr from 105 to 92 Ma, and then decreasing as major slip was transferred onto eastern thrusts. Exhumation was …

Miocene-Quaternary Deformation Along The Central Maynard Lake Fault, Pahranagat Shear Zone, Nevada, Alexander Peck

UNLV Theses, Dissertations, Professional Papers, and Capstones

The left-lateral Pahranagat shear zone (PSZ) and Caliente-Enterprise zone (CEZ) exist at the boundary between two sub-provinces, the Northern (NBR) and Central Basin and Range (CBR). The PSZ contains three major ENE striking sinistral faults, including the Maynard Lake fault (MLF), which is the longest fault and marks the southern boundary of the zone. The PSZ has been suggested to be a transfer zone, but little is known about the structures along these major faults that are involved in strain transfer. These left-lateral systems exist within the Central Nevada seismic belt which has experienced significant earthquakes in recent history. Possible …

Kinematics And Timing Of The Miocene-Quaternary Deformation In Nellis Dunes Recreational Area, Nevada, Shaimaa Abdelhaleem

UNLV Theses, Dissertations, Professional Papers, and Capstones

The kinematics and origin of transfer, accommodation and strike-slip zones is of paramount significance in understanding continental extension. The Las Vegas Valley Shear Zone (LVVSZ) is a NW-striking right-lateral fault system in the central Basin and Range province. Despite its prominence among the structures of the region and its role in the regional tectonic development, little is understood about its eastern portion. The inadequately constrained trace of the LVVSZ along its eastern part contributes largely to the ambiguity of the time activity and role of the LVVSZ. The eastern part of LVVSZ lies in Nellis Dunes Recreational Area (NDRA), north …

Thermal Impacts Of Salt On Sandstones And Mudstones In The Lusitanian Basin, Portugal, Brett Perry

UNLV Theses, Dissertations, Professional Papers, and Capstones

In order to assess the impact of salt structures on paleotemperatures in adjacent sedimentary rocks, a field based study which quantified thermally driven diagenetic products as a function of distance from salt was undertaken. Several salt diapirs are now exposed at the surface of the Earth within the Lusitanian Basin and offered a unique opportunity to document paleothermal anomalies by studying thermally controlled diagenesis in adjacent, exposed Upper Jurassic rocks. Four transects were chosen within Upper Jurassic rocks that contained both sandstones and mudstones. Quartz cementation and albitization of feldspars, both of which are thermally driven processes, were quantified in …

Application Of (U-Th)/He And 40ar/39ar Thermochronology To The Age Of Thrust Faulting In The Sevier Orogenic Belt, Michael Giallorenzo

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Sevier fold-thrust belt of the Cordilleran orogen in the western United States is a well-studied geologic province, yet our understanding of the history of thrust faulting is still far from complete. Thermochronological methods are applied to major thrust systems from two distinct sections of the Sevier fold-thrust belt (SFTB): the Wheeler Pass thrust in the Mojave Desert section of the southern SFTB, and the Willard thrust in the Idaho-Utah-Wyoming section of the SFTB. The new thermochronological data greatly improve our understanding of the structural evolution of this extensive geologic province.

The zircon (U-Th)/He (ZHe) system records thrust-induced uplift and …

Pennsylvanian To Cretaceous Folds And Thrusts In South-Central Nevada: Evidence From The Timpahute Range, Angela Giovanna Russo

UNLV Theses, Dissertations, Professional Papers, and Capstones

Understanding Permian and Mesozoic contractional structures from southern California to northern Nevada requires correlation through south-central Nevada. After the Devonian-Mississippian Antler orogeny through the Permian-Triassic Sonoma orogeny and then up to the Sevier orogeny, south-central Nevada was thought to have remained tectonically inactive. However, Pennsylvanian through Jurassic age deformation is documented to the south in Death Valley and to the north. Identifying geometries, spatial relationships, and relative timing of deformations in the Timpahute Range, south-central Nevada, is an essential piece to completing the overall understanding of Nevada geology. The purpose of this study is to identify and analyze deformational structures …

Determining The Motion And Location Of The Frenchman Mountain Fault, Las Vegas, Nevada: A Paired Basin Analysis And Structural Analysis, Laura Margaret Eaton

UNLV Theses, Dissertations, Professional Papers, and Capstones

Understanding the evolution of large-scale fault systems remains a challenge to geologists and is of critical importance in understanding the dynamics of larger plate tectonic interactions. I mapped the southwestern Frenchman Mountain Fault (FMF), conducted a basin analysis of units in the footwall of the fault, and measured kinematic indicators along the fault zone in order to constrain fault offset, magnitude, and timing in an attempt to further our understanding of these systems.

My findings include: 1) the presence of vertical and sub-vertical slickenlines on southwest dipping fault surfaces indicative of normal sense offset; 2) relatively little lateral variation in …

Paleoseismic Study Of The Stewart Valley And Northern Pahrump Segments Of The Stateline Fault System, Nevada, Jonathan Carter

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Stateline fault system (SFS) is a ~200 km long zone of dextral faults running NW along the NV/CA border from Primm, Nevada to Amargosa Valley in the western Central Basin and Range province (CBR). Because of size and proximity, the SFS poses a hazard to the 2.5 million people, most of who live within 10 km, in Pahrump, Nevada and within 40 km, in Las Vegas, Nevada. The goals of this thesis are to (1) understand if the SFS is accommodating faulting slip change in the CBR; (2) test the along strike continuity of the SFS in Pahrump and …

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.

The Behavior Of Zircon During Partial Melting In Anatectic Migmatites: Insights To Metamorphism, Deformation And Tectonism In The Central Santa Fe Range, Northern New Mexico, Michelle Renee Stropky

UNLV Theses, Dissertations, Professional Papers, and Capstones

Three lithologic assemblages exposed in the central Santa Fe Range, northern New Mexico include (1) a septum of Proterozoic low temperature (~700oC, 5.5 kbars), semi-pelitic anatectic migmatites surrounded by (2) deformed megacrystic biotite granite that is intruded by (3) discrete plutons of largely undeformed hornblende biotite tonalite. Metamorphic fabrics in the migmatite record three deformation events (D1 - D3); a composite S1/S2 fabric (D1 and D2) that formed contemporaneous with anatexis and is folded about a southwest plunging map-scale (D3) antiform. The megacrystic granite exhibits a pervasive S1 subsolidus foliation that parallels the S1/S2 fabric in the migmatite and is …

Mesozoic Burial, Mesozoic And Cenozoic Exhumation Of The Funeral Mountains Core Complex, Death Valley, Southeastern California, Mengesha Assefa Beyene

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Funeral Mountains of Death Valley National Park, CA, provide an opportunity to date metamorphism resulting from crustal shortening and subsequent episodic extensional events in the Sevier hinterland. It was not clear whether crustal shortening and thus peak temperature metamorphism in the hinterland of the Sevier-Laramide orogenic wedge have occurred whether in Late Jurassic, Early Cretaceous , Late Cretaceous or somewhere between. Particularly ambiguous is the timing of crustal shortening in the deep levels of the hinterland of the Sevier belt, now manifest in the metamorphic core complexes, and how and when these middle-to-lower crustal rocks were exhumed. A 6-point …

Volatile Bubble Growth In The Aztec Wash Pluton, Brett Perry, Adam Simon, Rachael Johnsen

Festival of Communities: UG Symposium (Posters)

Plutons are well preserved magma chambers that have been preserved in the rock record and allow the study of magmatic processes. Magma chambers are composed of silicate magmas, crystals, and volatiles. Volatiles are a key control in driving eruptive processes, which vent greenhouse gases into the atmosphere, thus a better understanding of the mechanisms of volatile transport within a pluton is necessary. Microscopy was used to analyze the size and density of cavities and feldspars from various stratigraphic sections of the pluton. Microscopy showed that cavities were a result of volatile partial pressure, as well as, a progressive increase in …

In-Situ Synchrotron X-Ray Diffraction Study Of Quartz Deformation Using The D-Dia Apparatus, May Sas, Dawn Pape, Brian Erickson, Sylvia-Monique Thomas, Pamela Burnley

Festival of Communities: UG Symposium (Posters)

Deformation is a rock’s mechanical response to external parameters such as temperature and pressure. Knowledge of deformation is necessary to understand geodynamic processes. The behavior of rocks and minerals during deformation depends on the behavior of individual grains within those minerals as they interact. The mineral we are studying is quartz, which we chose since it is very well studied and is highly abundant. We use high-pressure high temperature experiments to simulate conditions of Earth’s interior and the D-DIA apparatus combined with synchrotron x-ray diffraction allows us to record data directly during the process of deformation. The data we collect …

Late Paleozoic Deformation In The Osgood Mountains And Dry Hills, Northern Nevada, Samuel A. Siebenaler

UNLV Theses, Dissertations, Professional Papers, and Capstones

Pennsylvanian (IP) and Permian (P) deposits (Etchart Formation) and structures in the northern Osgood Mountains and Dry Hills are identified and interpreted to reconstruct a late Paleozoic tectonic history for the time between the Antler and Sonoma orogenies. Mapping, field observations, fusulinid-based unit ages, and structural analysis are used to identify three fold and fault sets, a fault set, a fold set, and at least two angular unconformities. The faults consist of N to S striking normal faults (fault set 1) that are cross cut by WSW-ENE striking thrust faults (fault set 2). Fault sets 1 and 2 are cross …

In Situ Element Quantification In The Hydrothermal Diamond Anvil Cell Using Synchrotron X-Ray Fluorescence With Applications Toward Subduction Zone Processes, Steven Joseph Maglio

UNLV Theses, Dissertations, Professional Papers, and Capstones

Yttrium is used in geochemical investigations of arc volcanics and metamorphic geothermometers. The ability to use Y as a geochemical tool is predicated on an understanding of the mobility of Y during fluid-saturated conditions attending metamorphic and igneous processes. The goal of this work was to use the hydrothermal diamond anvil cell (HDAC) and synchrotron radiation X-ray fluorescence to quantify, in situ, the concentration of Y in aqueous fluids at 2-5 GPa and 650 - 800 °C; conditions likely at the oceanic lithosphere - mantle wedge interface in subduction zones. Previous studies have used modified diamond anvils which limits their …

Final Report: Task 22 — Extreme Ground Motion Studies, John G. Anderson, James N. Brune, Jaak J.K. Daemen, Matthew Purvance

Publications (YM)

TASK 22 consisted of two separate investigations into extreme ground motions due to seismic events, Subtask 1 and Subtask 2. Subtask 1 included field studies of geological formations that should put an upper bound on extreme ground motions that have happened at the site of the formations. The locations are critically selected to provide the most effective constraints possible on the validity of the probabilistic seismic hazard analysis for Yucca Mountain. Subtask 2 surveyed recorded ground motions from around the world, with the aim to draw general conclusions from these as to the conditions where extreme ground motions are observed. …

Kinematics And Timing Of Orogen-Parallel Flow, Grouse Creek Mountains, Utah, Tonia Gail Arriola

UNLV Theses, Dissertations, Professional Papers, and Capstones

Alternating contractional and extensional events in orogenic belts play a significant role in dynamically adjusting crustal thickness during regional contraction. Distinguishing between these two contrasting kinematic regimes is not only important for understanding the tectonic setting but also provides insights into the dynamics of evolving orogenic wedges. The earliest pervasive fabric, D ₁ , in the Grouse Creek Mountains of northwest Utah is interpreted to have played an integral role in accommodating such a dynamic adjustment. It is interpreted that focused crustal thickening led to differences in gravitational potential energy along strike, facilitating an episode of mid-Cretaceous synconvergent orogen-parallel extension. …

Imaging The Southern Trace Of The Black Hills Fault, Clark County, Nevada, Shelley A. Zaragoza

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Black Hills fault (BHF) is a SE-dipping normal fault forming the northwestern structural boundary of the Eldorado basin, ∼20 km southeast of Las Vegas, Nevada (Langenheim and Schmidt, 1996). The fault offsets Holocene strata and is thus considered to be active (Fossett, 2005). Therefore, the BHF poses a significant seismic hazard to the greater Las Vegas area.

Fossett (2005) estimated that the BHF is capable of producing a M _W 6.4 to 6.8 earthquake. However, this suggests a subsurface rupture length greater than the scarp length (Fossett, 2005). To test this hypothesis, remote sensing, geologic mapping, and high-resolution seismic …

Exceptional Ground Accelerations And Velocities Caused By Earthquakes, John G. Anderson, James N. Brune

Publications (YM)

This project aims to understand the characteristics of the free-field strong-motion records that have yielded the 100 largest peak accelerations and the 100 largest peak velocities recorded to date. The peak is defined as the maximum magnitude of the acceleration or velocity vector during the strong shaking. This compilation includes 35 records with peak acceleration greater than gravity, and 41 records with peak velocities greater than 100 cm/s. The results represent an estimated 150,000 instrument-years of strong-motion recordings. The mean horizontal acceleration or velocity, as used for the NGA ground motion models, is typically 0.76 times the magnitude of this …

Seismicity In The Vicinity Of Yucca Mountain, Nevada, For The Period October 1, 2002 To September 30, 2003, Ken Smith, David Vin Seggern, John G. Anderson, Richard Quittmeyer, Amy J. Smiecinski

Publications (YM)

Earthquake activity in the Yucca Mountain from October 1, 2002 through September 30, 2003 (FY03) is assessed and compared with previous activity in the region. FY03 is the first reporting year since the 1992 M 5.6 Little Skull Mountain earthquake with no earthquakes greater than M 3.0 within 65 km of Yucca Mountain. In addition, FY03 includes the fewest number of earthquakes greater than M 2.0 in any reporting year since the LSM event. With 3075 earthquakes in the catalog, FY03 represents the second largest number of earthquakes (second to FY02) since FY96 when digital seismic network operations began. The …

Seismicity In The Vicinity Of Yucca Mountain, Nevada, For The Period October 1, 2003, To September 30, 2004, David Von Seggern, Ken Smith, John G. Anderson, Amy J. Smiecinski

Publications (YM)

This report describes the seismicity and earthquake monitoring activities within the Yucca Mountain region during fiscal year 2004 (FY2004 - October 1, 2003, through September 30, 2004) based on operation of the Southern Great Basin Digital Seismic Network (SGBDSN). Network practices and earthquake monitoring conducted at the Nevada Seismological Laboratory (NSL) under DOE directives for prior fiscal years are covered in similar yearly reports (see references). Real-time systems, including regional data telemetry and data management at NSL, provide for the automatic determination of earthquake locations and magnitudes and notification of important earthquakes in the region to UNR staff and DOE …

Extreme Ground Motion Studies, James N. Brune, John G. Anderson

Publications (YM)

Subtasks:

1. Constraints on Yucca Mountain extreme ground motion based on precariously balanced rocks, unstable precipitous cliffs, and un-fractured sandstone along the San Andreas fault.

2. Prepare summary report on large recorded ground motions.

Geodetic Monitoring Of The Yucca Mountain Region Using Continuous Gps Measurements, Geoff Blewitt, Jonathan Price, Nevada Geodetic Laboratory, Nevada Bureau Of Mines & Geology

Publications (YM)

What Task 3 is About: Monitor current crustal deformation at YM
– In the broader tectonic context of the NA-Pacific plate boundary
– In the regional context of the East California Shear Zone (ECSZ)
– In the geological context of specific fault activity
– Vertical motion associated with geophysical fluids

Using geodetic methods
– GPS – mature, proven
track the 3-D point-positions of 47 stations with < 1 mm precision
– InSAR – new, experimental
regional map of displacement along the line-of-sight (accuracy??)
proven capability: (1) co-seismic deformation; (2) local instabilities

Longbase Laser Strainmeter Measurements At Yucca Mountain, James N. Brune

Publications (YM)

Why Operate a Strainmeter? To monitor strain over a broader bandwidth and with much higher sensitivity than GPS (or other instruments):
– Measure strain from seismic, earth-tide, temperature and air pressure inputs--gives local rock properties, and changes in them.
– Independently constrains GPS results.

To directly measure in the Yucca Mountain Block:
– Sensitive to potential very local tectonic events, (including any triggered slip), or volcanic events.

To establish a baseline for future strain changes:
– E.g., events developing from loading and heating of the repository

Geostatistical And Stochastic Study Of Radionuclide Transport In The Unsaturated Zone At Yucca Mountain, Feng Pan, Ming Ye, Jianting Zhu

Publications (YM)

Motivation: Why Study of Unsaturated Zone?

The unsaturated zone (UZ), where the proposed repository would be located, acts as a critical natural barrier by delaying the arrival of radionuclides at the saturated zone and by reducing radionuclide concentrations in groundwater through dispersion and dilution

Quantitative prediction of radionuclide transport in the unsaturated zone becomes critical for performance assessment and design of the proposed repository of the Yucca Mountain Project

Unlv Magazine, Carol C. Harter, Joe Cockrell, Tony Allen, Regina Bacolas, Lori Bachand, Jennifer Lawson, Bret C. Birdsong, Steve Parker, Erin O'Donnell, Jennifer Robison

UNLV Magazine

No abstract provided.

Paleoseismology Of The Black Hills Fault, Southern Nevada, And Implications For Regional Tectonics, Eric Fossett

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Black Hills fault (BHF) is a Holocene fault located in Eldorado Valley, approximately 7 km from Boulder City, southern Nevada. The importance of this study is to determine the seismic hazards the BHF poses to Boulder City and the greater Las Vegas metropolitan area and to determine the mechanisms driving the young deformation in the Lake Mead region. The BHF is a multistranded fault that had five surface rupturing paleoearthquake events in the past approximately 25 ka. Paleoseismic fault offsets indicate that the BHF is capable of generating a Mw = 6.4-6.9 earthquake. Slip rates calculated for the BHF …