Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- New Mexico (13)
- Seismology (8)
- Geochemistry (7)
- Colorado Plateau (6)
- Mars (6)
-
- Stratigraphy (6)
- Geology (5)
- Geomorphology (5)
- San Juan Basin (5)
- Tectonics (5)
- Hydrology (4)
- Meteorites (4)
- Volcano (4)
- Chondrites (3)
- Geochronology (3)
- Grand Canyon (3)
- Incision (3)
- Mantle (3)
- Petrology (3)
- Stable isotopes (3)
- Volatiles (3)
- Yellowstone (3)
- Active Source Seismology (2)
- Amalgamation (2)
- Anoxia (2)
- Campanian (2)
- ChemCam (2)
- Climate (2)
- Climate Change (2)
- Detrital sanidine (2)
Articles 1 - 30 of 284
Full-Text Articles in Physical Sciences and Mathematics
Late Cretaceous Ammonites And Other Non-Rudist Mollusks From Costa Rica And Their Paleoecology, Esteban David Lopez-Murillo
Late Cretaceous Ammonites And Other Non-Rudist Mollusks From Costa Rica And Their Paleoecology, Esteban David Lopez-Murillo
Earth and Planetary Sciences ETDs
The Nicoya region in northwestern Costa Rica contains a rich record of Upper Cretaceous fossiliferous sediments, which have received variable levels of study over the past several decades. In particular, rudists from these deposits have been well-characterized, however, the non-rudist ammonite, gastropod, and bivalve fauna have received much less attention. However, this area is particularly important because the Nicoya region was attached to the southernmost tip of North America, making it a unique crossroad between the western Tethys (Caribbean) and Pacific Oceans. Here I present a detailed investigation of these rocks and their fauna between the Late Campanian to Early …
Crustal Structure And Evolution Of The Queen Charlotte Plate Boundary, Collin C. Brandl
Crustal Structure And Evolution Of The Queen Charlotte Plate Boundary, Collin C. Brandl
Earth and Planetary Sciences ETDs
There are many outstanding questions in plate tectonics that remain unanswered because large regions of the Earth are unexplored, both at the surface and in the subsurface. In this dissertation, I processed and analyzed active source seismic reflection data from the historically understudied Queen Charlotte transform plate boundary. Using this dataset, I found that the southern segment of the plate boundary has active underthrusting, is analogous to subduction zone crustal slivers, and is a site of early subduction initiation. Along the entire plate boundary, I constrained the near-surface thermal gradient using the stability of gas hydrate, finding that it is …
Differential River Incision Due To Quaternary Faulting On The Río Jemez-Salado System At The Million-Year Timescale, Cameron Reed
Differential River Incision Due To Quaternary Faulting On The Río Jemez-Salado System At The Million-Year Timescale, Cameron Reed
Earth and Planetary Sciences ETDs
Analysis of long-term average bedrock incision rates along the Río Salado-Jemez system using fluvial terraces can be used to test and quantify the hypothesis that differential river incision reflects Quaternary fault slip during ongoing uplift of the Jemez and Nacimiento Mountains. Terrace flights were correlated from the Arroyo Peñasco to the Río Salado near the southern nose of the Nacimiento and along the Río Jemez. Using highest/oldest river terraces, resulting bedrock incision values average out glacial/interglacial cycles and are interpreted to reflect differential uplift. For previously mapped and correlated terraces, we applied lidar datasets to refine strath heights. We also …
Proterozoic Tectonic Evolution Of The Lower Granite Gorge, Grand Canyon, Arizona: A Middle Crustal Record Of Multiple Orogenic Pulses, John M. Bailey
Proterozoic Tectonic Evolution Of The Lower Granite Gorge, Grand Canyon, Arizona: A Middle Crustal Record Of Multiple Orogenic Pulses, John M. Bailey
Earth and Planetary Sciences ETDs
The well-exposed basement transect in the Lower Granite Gorge (LGG) of western Grand Canyon provides a middle-crustal record of suturing crustal blocks during the Proterozoic accretionary history of southwestern Laurentia. Orogenic evolution included at least three stages: (1) subduction-related ~1.75-1.72 Ga volcanic arc magmatism, turbidite deposition, and suturing of arc terranes with different crustal thicknesses; (2) intense northwest-southeast crustal shortening at ca. 1.71-1.68 Ga to form the Vishnu Mountains during the Yavapai orogeny; (3) dextral strike-slip shear zones development at ~1.4 Ga during long-term crustal residence and slow cooling above ~250 °C (~10 km) until ~1.3 Ga. Final cooling from …
Chemical And Morphological Characterization Of Airborne Particulate Matter At The Jackpile-Paguate Mine, Pueblo Of Laguna, New Mexico: Implications For Potential Metals Exposure, Andreanna C. Roros
Chemical And Morphological Characterization Of Airborne Particulate Matter At The Jackpile-Paguate Mine, Pueblo Of Laguna, New Mexico: Implications For Potential Metals Exposure, Andreanna C. Roros
Earth and Planetary Sciences ETDs
The inhalation of windblown particulate matter (PM) derived from abandoned uranium mines (AUMs) is a potential environmental health risk to Native American communities that live in proximity to these sites. However, the aeolian transport of metal-bearing PM from AUMs, as a potential exposure pathway, has not been investigated in any detail. In this study, we sampled airborne particulate matter within the Jackpile Mine located on the lands of the Pueblo of Laguna, New Mexico using passive sampling methods to understand the characteristics of dust within the mine site. The objective was to determine the elemental concentrations, mineralogy, and morphology of …
Sulfur Sequestration In Anhydrite Through Alteration Of Calcic Wall Rock, Lexi Kenis
Sulfur Sequestration In Anhydrite Through Alteration Of Calcic Wall Rock, Lexi Kenis
Earth and Planetary Sciences ETDs
Heterogeneous gas-solid reactions are suggested as a potential mecha-
nism for sequestering gaseous sulfur through the alteration of calcic wall
rocks. This study explores the concept of a “hierarchy of reactions” pro-
posed by Giggenbach (1987), outlining the interplay between gas components
and redox-related minerals in volcanic wall rocks. Mt. Pinatubo provides a
more felsic composition and more oxidizing conditions compared to previ-
ously studied volcanoes, Kudryavy and Erta Ale (Henley and Fischer, 2021),
and Lascar a more oxidizing case with a similar composition. By employing
thermodynamic models and synthetic melt experiments, evaluations of effi-
ciency of sulfur sequestration across …
Sand, Ice, And X-Rays: Developing Xct Methods For Frozen Samples And Refining Siliciclastic Facies Models For Perennially Ice-Covered Lakes, Utilizing Cores From Lake Fryxell, Mcmurdo Dry Valleys, Antarctica, Holly M. Levett
Earth and Planetary Sciences ETDs
Sedimentation in perennially ice-covered lakes (PICLs) is proposed to be bi-modal, with mud deposited by stream inflow and sand deposited on the ice cover by aeolian processes and then melting through by absorption of solar radiation. Here, we consider Lake Fryxell, a PICL in the McMurdo Dry Valleys, and several lake bed cores about 30 cm in length, to better understand PICL facies through time, using micro X-ray CT (XCT). Using XCT images along with sieve and laser granulometry data, we constrained the grain-size of PICL deposits to dominantly medium / fine sand with a coarse component. The presence of …
Carbonate And Organic Proxies And The Impacts Of Climate On Lake Systems: Paleoclimate Interpretations From Lake Chalco, Mexico, Aria Holmes
Earth and Planetary Sciences ETDs
This project incorporates several lines of evidence to better understand the climate at Lake Chalco. Chapter 1 utilizes oxygen isotopes from carbonates and show that the Inter Tropical Convergence Zone varies on primarily glacial and millennial timescales; precession is not observed. These data indicate glacials periods were shallower and interglacials were wetter periods at Lake Chalco. Chapter 2 studies carbon, nitrogen, C/N, and TOC proxies and finds that the lake conditions during the glacials and interglacials are primarily a mixed algal-macrophyte-terrestrial organic matter. Deviations show that the lake during the interglacials had more algal organic matter- reflecting influxes of nutrients …
Unboxing The Complicated Near Term Climatic And Geomorphic History Of Mars, Joshua Matthew Williams
Unboxing The Complicated Near Term Climatic And Geomorphic History Of Mars, Joshua Matthew Williams
Earth and Planetary Sciences ETDs
It has long been thought that glacial processes were unlikely within the tropical regions of Mars. However, growing evidence, including this work has identified and quantified relic glacial forms within the equatorial regions. These findings have major implications for understanding Martian climate history and its sensitivity to changes in insolation. As well, the presence of ice in the equatorial region of Mars has significant implications for the past global redistribution of the water ice in the Martian cryosphere. In this manuscript, I clarify and refine our understanding of the morphology of glacial features in the equatorial zone by applying novel …
Paleoecology Of The Late Cretaceous Western Interior Seaway And Gulf Coastal Plain, Ceara Kathleen Quinn Purcell
Paleoecology Of The Late Cretaceous Western Interior Seaway And Gulf Coastal Plain, Ceara Kathleen Quinn Purcell
Earth and Planetary Sciences ETDs
This dissertation presents research into the paleobiogeography and paleoecology of the Western Interior Seaway (WIS) and Gulf Coastal Plain (GCP) during the Late Cretaceous. The dataset utilized here includes an extensive record of marine invertebrates from over 200 years of fossil collecting and sedimentary data collated from over 45 different literature sources, representing approximately 17 million years of deposition. The high-resolution of this dataset, and its extensive geographic distribution and temporal duration, make it ideal for exploring various ecological questions. Using these data, I have attempted to reconstruct paleobiogeographic provinces as published in prior works, explore functional diversity patterns, and …
Remote Sensing Techniques To Determine Volcanic Gas Components And Fluxes: Application For Lascar, Chile And Fagradalsfjall, Iceland Volcanos., Felipe S. Rojas Vilches
Remote Sensing Techniques To Determine Volcanic Gas Components And Fluxes: Application For Lascar, Chile And Fagradalsfjall, Iceland Volcanos., Felipe S. Rojas Vilches
Earth and Planetary Sciences ETDs
Volcanic plumes allow us to understand different aspects of a volcanic system including magma movements, dynamics, mass transfer, overall gas emissions to the atmosphere, and many processes that impact human life. However, the H₂O gas is poorly constrained due to the intrinsic difficulties of this gas, with high background values and easily dispersed/integrated into the background. In this work we study the gas emissions from Lascar volcano, and Fagradalsfjall volcano, in Chile and Iceland, respectively, using a combination of different ground-based remote sensing techniques and in situ plume measurements, we measure H₂O, SO₂, CO₂, CO, and H₂S from longer and …
Environmental Fate Of Sulfur In Sulphur Creek, Valles Caldera, Nm: Implications For Metal Transport And Water Quality, Daniel Lavery
Environmental Fate Of Sulfur In Sulphur Creek, Valles Caldera, Nm: Implications For Metal Transport And Water Quality, Daniel Lavery
Earth and Planetary Sciences ETDs
The 1.2 Ma Valles Caldera in north-central New Mexico hosts a young igneous volcanic hydrothermal system after the model proposed in Goff and Janik (2000). The Sulphur Springs area within Valles Caldera is an acid-sulfate area typical of this model, discharging acidic waters (pH 1.5-3) formed by oxidation of magmatic H2S at the surface. We report on samples obtained from springs and streams collected between October 2021 and May 2023 in the Sulphur Creek and Alamo watersheds. Sulphur Creek receives input from Sulphur Springs and exhibits low pH (2-4) and high concentrations of Al (≤110 mg/L), Fe (≤60 …
Hydrochemistry Of An Alpine Karst System, Northern New Mexico: Las Huertas, Kambray A. Townsend
Hydrochemistry Of An Alpine Karst System, Northern New Mexico: Las Huertas, Kambray A. Townsend
Earth and Planetary Sciences ETDs
Las Huertas in the Sandia Mountains relies on snowmelt, monsoonal recharge, and groundwater inputs. Our hypothesis, the proportion of groundwater contribution varied spatially and temporally, was assessed by observing travertine and multiple geochemical tracers to differentiate water balance components. We report 26 samples from 13 locations (sampled between 2021-2023). Major ion and isotopic analysis indicated Las Huertas headsprings vary spatially. Capulin Spring has higher salinity; major ions suggest recharged waters are a mix of CaCO3-rich and sulfate-chloride-containing water. The proportion of groundwater to spring discharge is a mix of winter and summer precipitation. Travertine supersaturation is seasonal, with variations downstream, …
Applications Of Observational Seismology: Insights Into Volcanic And Near Surface Processes, Justin T. Wilgus
Applications Of Observational Seismology: Insights Into Volcanic And Near Surface Processes, Justin T. Wilgus
Earth and Planetary Sciences ETDs
The field of observational seismology has made tremendous progress in the past two decades. This progress has been multi-faceted in form, but significant contributions emanated from 1) increases in both the quality and the quantity of seismic data 2) advances in computational power 3) advances in algorithmic capability, including machine learning. In this dissertation I report on three distinctly different seismic applications made possible by the aforementioned progress and discuss the insights these applications have provided in understanding volcanic and near surface processes of the Earth.
In the first chapter titled, “Shear Velocity Evidence of Upper Crustal Magma Storage Beneath …
Seismic Analysis Of The Upper & Lower Falls Of The Yellowstone River, Loring Schaible
Seismic Analysis Of The Upper & Lower Falls Of The Yellowstone River, Loring Schaible
Earth and Planetary Sciences ETDs
Twelve years of concurrent hydrologic and continuous seismic data along with temporary seismic data demonstrate that the Upper and Lower Falls of the Grand Canyon of the Yellowstone River comprise a highly localized source of 0.5-5 Hz seismic energy that overwhelms anthropogenic contributions. In aggregate, seismic amplitude from 2008-2019 is linearly related to discharge with a correlation coefficient of 0.96. Repeated deviations from this linear relationship persist for 1-2 weeks prior to the date that Yellowstone Lake becomes clear of winter ice coverage. Seismic efficiency increases by ~50-250% during this period of ice-breakup, during which lake ice flows into the …
Seismic Shadow Zone Investigation In The Upper Magma Reservoir Of The Yellowstone Caldera, Sarah Nolt-Caraway
Seismic Shadow Zone Investigation In The Upper Magma Reservoir Of The Yellowstone Caldera, Sarah Nolt-Caraway
Earth and Planetary Sciences ETDs
This study investigates whether the Yellowstone Caldera has enough melt to mute S-waves, creating a seismic shadow zone. Using a dense nodal deployment of ~650 stations, 7-9 earthquakes during the nodal deployment, and 21 broadband stations with 3,000-4,000 events per station; amplitude and noise maps, seismograms, and automatic phase picks probabilities from a deep learning model were analyzed to assess the potential role of melt, crustal attenuation, and noise in affecting body waves, particularly S-phases. The results are inconclusive, with unclear evidence whether observed amplitude decay is normal signal decay due to distance, noise-related, melt, or from scattering and intrinsic …
Assessing Ecological Relationships Among Late Triassic Vertebrates In Petrified Forest National Park, Alexandra Davis Apgar
Assessing Ecological Relationships Among Late Triassic Vertebrates In Petrified Forest National Park, Alexandra Davis Apgar
Earth and Planetary Sciences ETDs
The complex vertebrate ecosystem of the Late Triassic has not yet been fully understood, largely due to oversimplification of hypothesized trophic hierarchies and limited preservation of direct evidence of faunal interaction. Paleocommunity reconstruction attempts can also fall victim to taphonomic biases, time-averaging inaccuracies, and non-analogue paleoecologies. Utilizing a combination of PAIRS analysis and NMDS ordination, we highlight vertebrate faunal relationships within the Adamanian and Revueltian faunachrons of Petrified Forest National Park, assess the likelihood that these patterns have ecological rather than preservational drivers, and examine how these potential interactions may have been impacted by the Adamanian-Revueltian turnover event. We are …
Bulk Hydrogen Isotopes In Ordinary Chondrites, Michael J. Cato
Bulk Hydrogen Isotopes In Ordinary Chondrites, Michael J. Cato
Earth and Planetary Sciences ETDs
Bulk hydrogen isotopes in nominally anhydrous meteorites are a key component in our understanding of the distribution of hydrogen in our solar system, including the provenance of water on the Earth. Here, we develop a step-heated continuous-flow method to measure the bulk hydrogen isotopes in nominally anhydrous rocks and use this method to significantly increase the dataset of bulk hydrogen isotopes in ordinary chondrites, nearly doubling the number of equilibrated members. We found that as thermal alteration increases from petrologic type 3.0 to 4, there is a correlated decrease in both hydrogen content and isotope ratio, followed by no significant …
Evaluation Of Fluvial Package Amalgamation In Medial Dfs Deposits, Angel Peak Area, Nacimineto Formation, Sarah R. Rysanek
Evaluation Of Fluvial Package Amalgamation In Medial Dfs Deposits, Angel Peak Area, Nacimineto Formation, Sarah R. Rysanek
Earth and Planetary Sciences ETDs
Fluvial packages are the hypothetical groupings of facies that make up the fluvial succession consisting of channel belt sandstones and associated levee, floodplain, and avulsion deposits. This study attempted to describe a single fluvial package laterally using the new technologies of UAV imaging and 3D photogrammetry; however, amalgamation of channel belts and erosion from this amalgamation made long-distance lateral correlation difficult. This analysis of medial deposits in the Nacimiento Formation in the Angel Peak Area, Northwestern New Mexico evaluates the degree of amalgamation of fluvial packages across the study area while identifying facies associated with the hypothetical fluvial package. This …
Single-Crystal Elasticity Of Earth’S Mantle Transition Zone Minerals And High Pressure-Temperature Phase Equilibrium Experiments On Martian Basalts, Wenyi Zhou
Earth and Planetary Sciences ETDs
Wadsleyite and ringwoodite are major minerals in the Earth’s Mantle Transition Zone. Global and local seismic studies have detected strong lateral variations in seismic velocity and anisotropy in the Mantle Transition Zone, reflecting temperature and possible composition variations. Interpretation of these seismic observations requires knowledge of thermoelastic properties of wadsleyite and ringwoodite with different compositions (water and Fe contents) under high pressure-temperature conditions. In this dissertation, we have measured single-crystal elastic properties of wadsleyite and ringwoodite under high pressure-temperature conditions by Brillouin spectroscopy. Based on our measurements and previous experimental results, we further model the effects of water and Fe …
Induced Seismicity In The Raton Basin And Global Variability Of The 410-Km Discontinuity, Margaret E. Glasgow
Induced Seismicity In The Raton Basin And Global Variability Of The 410-Km Discontinuity, Margaret E. Glasgow
Earth and Planetary Sciences ETDs
Natural processes like mantle convection and plate tectonics dominate Earth’s seismic structure. Recently human activities have increasingly influenced the deformation of the shallow crust. In this dissertation, passive source seismology was used to constrain seismic discontinuities in the mantle transition zone and seismogenic structures in induced earthquake settings. Using a novel sampling method and uniform processing approach, I found the 410-km discontinuity is thermally and compositionally variable. Using a machine- learning approach, I found the three main zones of seismicity in the Raton Basin consist of short faults or fault segments with variable orientations. The zone that hosted a Mw …
A Rapid High-Precision Analytical Method For Triple Oxygen Isotope Analysis Of Co2 Gas Using Tunable Infrared Laser Direct Absorption Spectroscopy, Nathan Perdue, Zachary Sharp, David Nelson Jr., Rick Wehr, Christoph Dyroff
A Rapid High-Precision Analytical Method For Triple Oxygen Isotope Analysis Of Co2 Gas Using Tunable Infrared Laser Direct Absorption Spectroscopy, Nathan Perdue, Zachary Sharp, David Nelson Jr., Rick Wehr, Christoph Dyroff
Earth and Planetary Sciences ETDs
Rationale
The simultaneous analysis of the three stable isotopes of oxygen – triple oxygen isotope analysis – has become an important analytical technique in natural sciences. Determination of the abundance of the rare 17O isotope in CO2 gas using magnetic sector isotope ratio mass spectrometry is complicated by the isobaric interference of 17O by 13C (13C16O16O and 12C16O17O both have mass 45 amu). A number of analytical techniques have been used to measure the 17O/16O ratio of CO2 gas. They …
Single-Crystal Elasticity Of Clinopyroxenes And The Viscosity Of Kimberlite Magma Under High Pressure-Temperature Conditions, Ming Hao
Earth and Planetary Sciences ETDs
Clinopyroxene is not only an important mineral phase in the pyrolitic upper mantle, but also one of the dominated mineral phases in the subducted or delaminated eclogitic materials in the deep Earth. Identifying and locating these eclogitic materials requires the knowledge of the thermoelastic properties of clinopyroxene under high pressure-temperature conditions. In this dissertation, we have measured the single-crystal elastic properties of jadeite and omphacite, which are major clinopyroxene phases in the eclogitic materials, up to 18 GPa 700 K by Brillouin spectroscopy and utilized these data to identify the eclogitic heterogeneities in the mantle.
We also measured the viscosity …
Observational Constraints On The 520 Km Mantle Discontinuity, Mantle Transition Zone Anisotropy, And Local Seismicity At Mount St. Helens, Han Zhang
Earth and Planetary Sciences ETDs
Seismology provides valuable observational constraints to thermal and compositional states at inaccessible depths via understanding how elastic wave propagating through them. While many of fundament questions regarding solid Earth structures have been addressed during its more than 100 years history, some details remain unfilled and carefully designed approaches are needed to complete the pictures. This dissertation contributes observational constraints on three topics with newly developed methods. 1) We detected a controversial mantle discontinuity at about 520 km and concluded a mean mantle composition close to the Pyrolite model based on its seismic properties. 2) We isolated anisotropic effects in mantle …
Tree Ring Isotopic Reconstruction Of Hurricane Dolores, Jonathan Kane
Tree Ring Isotopic Reconstruction Of Hurricane Dolores, Jonathan Kane
Earth and Planetary Sciences ETDs
Tree rings contain high-resolution climate proxies of temperature and precipitation (Hughes et al., 1982; Fritts 2012; Scuderi 1993). The objective of this study was to use tree ring cellulose, specifically measuring δ18O - the oxygen-18 to oxygen-16 stable isotope ratio- to investigate the impact of Hurricane Dolores, a tropical cyclone that produced heavy precipitation in the Sierra Nevada in July 2015. Prior studies (Berkelhammer and Stott, 2008, 2009) have shown that conifer forests in California record the influence of varying precipitation regimes in their ring alpha-cellulose. Hurricane Dolores produced an intense precipitation event that inundated parts of the Mojave Desert …
Using Triple Oxygen Isotopes To Reveal The Origin And Evolution Of Mantle Eclogite, Catherine Mary Peshek
Using Triple Oxygen Isotopes To Reveal The Origin And Evolution Of Mantle Eclogite, Catherine Mary Peshek
Earth and Planetary Sciences ETDs
Triple oxygen isotope (TOI) measurements of mantle eclogite from the Orapa kimberlite pipe have reconstructed bulk rock '18O values from 4.587 to 9.542‰ (vs. VSMOW) and '17O from -0.075 to -0.044‰ (vs. VSMOW, ~0.528). TOI values show increasing '18O with decreasing '17O, overlapping with modern measured altered oceanic crust. Orapa eclogite xenoliths with alkali enrichments show variable mantle-like and heavy 18O, consistent with subduction of seafloor altered basalt. Na# (Na/Na+Ca) in clinopyroxene for some xenoliths pairs with mantle-like oxygen, variable and extreme LREE enrichment, elevated Mg# and lower jadeite contents. These samples preserve records of eclogite melting, mantle interaction …
Geochemical And Sensor-Based Monitoring Of Fault-Associated Carbonic Springs In Grand Canyon And Northern New Mexico: Identifying Hydrologic Pathways And Establishing Baselines, Chris Mcgibbon
Earth and Planetary Sciences ETDs
This dissertation examines the interaction of spring systems and faulting. When springs discharge within a fault zone the interaction is often complex, and multiple methods are required to understand the flow, mixing and evolution of groundwater. In karst aquifer systems fracture networks can range from sub-millimeter to meters and only adds to the complexities involved in examining spring hydrology. The Interest in springs and faulting is not only driven by science, but also has applied applications. Faulting and fluid flow are of interest to the oil and gas industry, and potential CO2 sequestration. In the southwestern US, water quantity …
The Birth And Incision History Of The San Juan River In The Past 5 Ma, Micael T. Albonico
The Birth And Incision History Of The San Juan River In The Past 5 Ma, Micael T. Albonico
Earth and Planetary Sciences ETDs
This study addresses the evolution of the San Juan River system and its confluence with the Colorado River, ~ 100 km above the regionally important Lees Ferry knickzone. The San Juan River is a 600-km-long continental-scale tributary of the Colorado River. From its headwaters in the San Juan Mountains in Colorado, the San Juan River flows across the Colorado Plateau, and into the Colorado River upstream of Grand Canyon. Published apatite fission track and apatite (U-Th)/He thermochronologic data show that rocks in Marble Canyon, as well as in middle and upper reaches of the San Juan River, were >75 °C …
The Morphology And Evolution Of Transverse Aeolian Ridges On Mars, Timothy Paul Nagle-Mcnaughton
The Morphology And Evolution Of Transverse Aeolian Ridges On Mars, Timothy Paul Nagle-Mcnaughton
Earth and Planetary Sciences ETDs
Transverse aeolian ridges (TARs) are enigmatic and largely relict bedforms on the surface of Mars. TARs are sparsely distributed but common on Mars, but their history, preservation, and past role in the sediment cycle is not well understood. First described in 2003, and detailed extensively in 2008, our study of TARs has been narrowly focused in the last decade, with more and more research noting their presence, but little investigation of the features themselves. Recent work has mostly focused on identifying Terran analogues for TARs, but TARs remain largely a unique Martian feature. In this manuscript, I clarify and refine …
Single-Crystal Elasticity Of Tremolite At High-Pressure Conditions And Its Implication For The Mid-Lithospheric Discontinuity, Soisiri Charin
Single-Crystal Elasticity Of Tremolite At High-Pressure Conditions And Its Implication For The Mid-Lithospheric Discontinuity, Soisiri Charin
Earth and Planetary Sciences ETDs
Tremolite is the calcium magnesium amphibole that widely occurs in igneous and metamorphic rocks of the crustal and upper mantle lithosphere, especially in the greenschist facies to amphibolite facies of ultramafic assemblages. The stability field of amphibole reaches 3-4 GPa and 1100-1200°C depending on water content and cation substitutions giving rise to amphibole to occur in highly variable compositions. This P-T condition, corresponding to the depth about 80-120 km, coincides with the depth range that a negative velocity gradient usually found within most stable cratonic lithospheres. This depth range is seismically called Mid-lithosphere discontinuity (MLD). The geologic processes that might …