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Crustal Architecture Of The Northwestern And Central Gulf Of Mexico From Integrated Geophysical Analysis, Irina Filina

Department of Earth and Atmospheric Sciences: Faculty Publications

The tectonic history of the Gulf of Mexico (GOM) is a subject for ongoing debate. The nature of the crust in the northwestern and central parts of the basin remains poorly understood. Joined interpretation of two 2D seismic cross sections—GUMBO1 and GUMBO2—with potential fields (gravity and magnetics) constrained with available well data allows testing various hypotheses about the subsurface structures and crustal architecture in the study area. In the northwestern GOM, two contradicting hypotheses about the nature of the crust were tested—exhumed mantle versus a thinned and intruded continental crust resulted from magma-rich rifting. The nature of the crust was …

Measurement And Characterization Of Infrasound From A Tornado Producing Storm, Brian R. Elbing, Christopher E. Petrin, Matthew Van Den Broeke

Department of Earth and Atmospheric Sciences: Faculty Publications

A hail-producing supercell on 11 May 2017 produced a small tornado near Perkins, Oklahoma (35.97, –97.04) at 2013 UTC. Two infrasound microphones with a 59-m separation and a regional Doppler radar station were located 18.7 and 70 km from the tornado, respectively. Elevated infrasound levels were observed starting 7min before the verified tornado. Infrasound data below ~5Hz was contaminated with wind noise, but in the 5–50 Hz band the infrasound was independent of wind speed with a bearing angle that was consistent with the movement of the storm core that produced the tornado. During the tornado, a 75 dB peak …

Integrated Imaging: A Powerful But Undervalued Tool, Irina Filina, Ed K. Biegert, Luise Sander, Victoria Tschirhart, Neda Bundalo, Cara Schiek-Stewart

Department of Earth and Atmospheric Sciences: Faculty Publications

Following the 2018 SEG Annual Meeting, the Gravity and Magnetics Committee held a postconvention workshop titled “Integrated Imaging.” The half-day workshop attracted nearly 50 participants from various backgrounds. Three primary objectives of the workshop were to explore the nonseismic toolbox, highlight real examples of integrated projects that benefited (or did not benefit) from nonseismic data, and provide geoscientists from all backgrounds a learning opportunity to see how they might optimize the value of their imaging projects via integration with relatively low-cost nonseismic methods. The workshop had a highly interactive format that differed from traditional presentation-based settings. After eight brief case …

La Evolucion De Glaciares De Escombros Y Morenas En La Cuenca Del Rio Blanco, Mendoza, William J. Wayne

Department of Earth and Atmospheric Sciences: Faculty Publications

RESUMEN: La subcuenca del río Blanco en el cordón del Plata, que incluye los valles de Angostura y Vallecitos, tiene 85 km², de los cuales 4.7 km² son de glaciares de escombros activos, 7.4 km" de glaciares de escombros fósiles y morrenas. Los dos valles con rumbo al sureste son erosionados en rocas volcánicas y contienen largas lenguas de glaciares de escombros que se extienden hasta los 3.300 m. Los dos valles con rumbo al este tuvieron glaciares hasta tiempos recientes y en uno de ellos aún existe un glaciar cubierto. Los glaciares de escombros en …

Using Artificial Neural Networks To Predict Future Dryland Responses To Human And Climate Disturbances, C.E. Buckland, R.M. Bailey, D.S.G. Thomas

Department of Earth and Atmospheric Sciences: Faculty Publications

Land degradation and sediment remobilisation in dryland environments is considered to be a significant global environmental problem. Given the potential for currently stabilised dune systems to reactivate under climate change and increased anthropogenic pressures, identifying the role of external disturbances in driving geomorphic response is vitally important. We developed a novel approach, using artificial neural networks (ANNs) applied to time series of historical reactivation-deposition events from the Nebraska Sandhills, to determine the relationship between historic periods of sand deposition in semi-arid grasslands and external climatic conditions, land use pressures and wildfire occurrence. We show that both vegetation growth and sediment …

The Influence Of Fetch On The Holocene Thermal Structure Of Hidden Lake, Glacier National Park, Jeffery R. Stone, Jasmine E. Saros, Trisha L. Spanbauer

Department of Earth and Atmospheric Sciences: Faculty Publications

We use three-dimensional modeling of the basin of Hidden Lake, Montana, to assess the influence of effective fetch on diatom-inferred changes in mixing depths throughout the Holocene. The basin of Hidden Lake is characterized by a complex morphometry; for example, three-dimensional modeling of the lake basin indicates that a decrease in lake level of 2 m would result in complete isolation of the deepest part of the lake basin from the rest of the lake. Our model suggests that small changes in the lake surface elevation at Hidden Lake would produce threshold-like responses in effective fetch, which in turn would …

Testing Pyroxenite Versus Peridotite Sources For Marine Basalts Using U-Series Isotopes, Lynne J. Elkins, Bernard Bourdon, Sarah Lambart

Department of Earth and Atmospheric Sciences: Faculty Publications

Geochemically enriched signatures in global oceanic basalts have long indicated a heterogeneous mantle source, but the role of lithologic heterogeneity in producing mantle partial melts, particularly fertile pyroxenite rocks, remains unclear. Uranium-series disequilibria in basalts are particularly sensitive to the increased garnet mode and melting rates of pyroxenite rocks, making the system a useful indicator of mantle lithologic heterogeneity in the melt region for oceanic basalts. Here we summarize evidence for the presence and importance of pyroxenite rocks in the upper mantle and their role in melt generation of mid-ocean ridge basalts and ocean island basalts, with a synthesis of …

Spatiotemporal Changes In Extreme Precipitation And Its Dependence On Topography Over The Poyang Lake Basin, China, Xianghu Li, Qi Hu

Department of Earth and Atmospheric Sciences: Faculty Publications

Spatiotemporal changes in extreme precipitation at local scales in the context of climate warming are overwhelmingly important for prevention and mitigation of water-related disasters and also provide critical information for effective water resources management. In this study, the variability and trends of extreme precipitation in both time and space in the Poyang Lake basin over the period of 1960–2012 are analyzed. Also, changes in precipitation extremes with topography are investigated, and possible causes are briefly discussed. ,e results show that extreme precipitation over the Poyang Lake basin is intensified during the last 50 years, especially the increasing trends are more …

Radar Quantification, Temporal Analysis And Influence Of Atmospheric Conditions On A Roost Of American Robins (Turdus Migratorius) In Oklahoma, Matthew S. Van Den Broeke

Department of Earth and Atmospheric Sciences: Faculty Publications

Radar observations present a way to monitor large, mobile populations across long temporal scales, and are especially valuable when individual scatterers are challenging to count visually. The focus of this study is a large and relatively homogeneous wintertime roost of American Robins (Turdus migratorius) in central Oklahoma. Radar observations are used to estimate the roost population through winter 2010–2011, and the population time series is related to weather variables and radar beam propagation. Radar-estimated roost population gradually increased to an estimated peak of 1.5–2 million individuals from November 2010 to January 2011, and then decreased in a more …

Sensitivity Of Potential Groundwater Recharge To Projected Climate Change Scenarios: A Site-Specific Study In The Nebraska Sand Hills, Usa, Zablon A. Adane, Vitaly A. Zlotnik, Nathan R. Rossman, Tiejun Wang, Paolo Nasta

Department of Earth and Atmospheric Sciences: Faculty Publications

Assessing the relationship between climate forcings and groundwater recharge (GR) rates in semi-arid regions is critical for water resources management. This study presents the impact of climate forecasts on GR within a probabilistic framework in a site-specific study in the Nebraska Sand Hills (NSH), the largest stabilized sand dune region in the USA containing the greatest recharge rates within the High Plains Aquifer. A total of 19 downscaled climate projections were used to evaluate the impact of precipitation and reference evapotranspiration on GR rates simulated by using HYDRUS 1-D. The analysis of the decadal aridity index (AI) indicates that climate …

Rinded, Iron-Oxide Concretions In Navajo Sandstone Along The Trail To Upper Calf Creek Falls, Garfield County, David Loope, Richard Kettler

Department of Earth and Atmospheric Sciences: Faculty Publications

Concretions are hard rock masses, usually spheroidal, but commonly oblate or discoidal, that are formed by strongly localized precipitation of minerals in the pores of an otherwise weaker sedimentary rock (see Bates and Jackson, 1980, for a more extensive definition). The iron-oxide-rich concretions in the Jurassic Navajo Sandstone in southern Utah are unusual in two fundamental ways. First, they are cemented by iron oxide (Fe2O3, or Fe(OH)3); most other concretions are cemented by silica (SiO2), calcite (CaCO3), dolomite (CaMg(CO3)2), or siderite (FeCO3). Second, unlike other concretions, they are not strongly cemented throughout, but instead, the iron oxide is concentrated in …

Plant Root Systems Preserved In The Permian Cedar Mesa Sandstone At Moki Dugway, Southeastern Utah, David Loope

Department of Earth and Atmospheric Sciences: Faculty Publications

Rooted green plants represent the base of the food chain for most terrestrial ecosystems, but, compared to animal burrows, root systems are relatively rarely recognized in ancient sedimentary rocks. Plant roots that penetrate unconsolidated sand dunes, especially those containing not only quartz grains, but also abundant grains of calcite (CaCO₃), are commonly replaced by fine crystals of calcite (Klappa, 1980). These structures (known by geologists as rhizoliths from the Greek for “root rock”) are one form of calcite cemented soil and sediment called caliche (figure 1). Caliche crystallizes well above the water table and its calcite crystals are …

The Origin Of Shinarump Wonderstone, Hildale, Washington County, Richard Kettler, David Loope

Department of Earth and Atmospheric Sciences: Faculty Publications

Southern Utah’s “wonderstone” is Shinarump sandstone, variably cemented and stained with iron oxide, forming intricate patterns reminiscent of landscapes. It is cut and sold as absorbent drink coasters and decorative objects, and is seen in rock shops across the country. The wonderstone pattern comprises thick bands of iron oxide mineralization that fills pore space (referred to as iron oxide cement or IOC) and more delicate bands of iron oxide mineralization that coats sand grains but does not fill pore space (referred to as iron oxide stain or IOS) (figure 1).

The wonderstone pattern is of interest to geologists because it …

Effects Of The Sea Breeze Circulation On Soil Temperature Over Kuwait Using In Situ Observations And The Ecmwf Model, Hussain Alsarraf, Matthew V.D. Broeke, Hala Aljassar

Department of Earth and Atmospheric Sciences: Faculty Publications

Background: The mesoscale circulation over Kuwait is an important influence on changes in surface temperatures and soil temperatures.

Introduction: This paper presents two common summertime atmospheric features over Kuwait linking wind circulation to soil temperatures.

Methods: In this study, we use the European Centre for Medium-range Weather Forecasts ECMWF reanalysis ERA-Interim dataset to investigate effects of the synoptic scale and mesoscale circulations.

Results: The results show that a large-scale pressure gradient in summer typically leads to northerly winds over Kuwait, while a weak synoptic-scale pressure gradient leads to light easterly humid winds from the Persian Gulf, consistent with a mesoscale …

Defining The Morphological Quality Of Fossil Footprints. Problems And Principles Of Preservation In Tetrapod Ichnology With Examples From The Palaeozoic To The Present, Lorenzo Marchetti, Matteo Belvedere, Sebastian Voigt, Hendrik Klein, Diego Castanera, Ignacio Díaz-Martínez, Daniel Marty, Lida Xing, Silverio Feola, Ricardo N. Melchor, James O. Farlow

Department of Earth and Atmospheric Sciences: Faculty Publications

The morphology of fossil footprints is the basis of vertebrate footprint ichnology. However, the processes acting during and after trace fossil registration which are responsible for the final morphology have never been precisely defined, resulting in a dearth of nomenclature. Therefore, we discuss the concepts of ichnotaphonomy, ichnostratinomy, taphonomy, biostratinomy, registration and diagenesis and describe the processes acting on footprint morphology. In order to evaluate the morphological quality of tetrapod footprints, we introduce the concept of morphological preservation, which is related to the morphological quality of footprints (M-preservation, acronym MP), and distinguish it from physical preservation (P-preservation, acronym PP), which …

Crustal Structure Of Mesozoic Rifting In The Northeastern Gulf Of Mexico From Integration Of Seismic And Potential Fields Data, Mei Liu, Irina Filina, Paul Mann

Department of Earth and Atmospheric Sciences: Faculty Publications

We have investigated the crustal structure of a 400 km wide zone of thinned continental crust in the northeastern Gulf of Mexico (GOM) using gravity and magnetic modeling along two deeply penetrated seismic transects. Using this approach, we identify two zones of prominent, southward-dipping reflectors associated with 7–10 km thick, dense, and highly magnetic material. Previous workers have interpreted the zones as either coarse clastic redbeds of Mesozoic age that are tilted within half-grabens or seaward-dipping reflectors of magmatic origin. Both seismic reflection lines reveal a 10 km thick and 67 km wide northern zone of high density near the …

Developing A Department Of Transportation Winter Severity Index, Curtis L. Walker, Dylan Steinkruger, Pouya Gholizadeh, Sogand Hasanzedah, Mark Anderson, Behzad Esmaeili

Department of Earth and Atmospheric Sciences: Faculty Publications

Adverse weather conditions are responsible for millions of vehicular crashes, thousands of deaths, and billions of dollars per year in economic and congestion costs. Many transportation agencies utilize a performance or mobility metric to assess how well they maintain road access; however, there is only limited consideration of meteorological impacts to the success of their operations. This research develops the Nebraska winter severity index (NEWINS), which is a daily event-driven index derived for the Nebraska Department of Transportation (NDOT). The NEWINS includes a categorical storm classification framework to capture atmospheric conditions and possible road impacts across diverse spatial regions of …

Age And Pattern Of The Southern High-Latitude Continental End-Permian Extinction Constrained By Multiproxy Analysis, Christopher R. Fielding, Tracy D. Frank, Stephen Mcloughlin, Vivi Vajda, Chris Mays, Allen P. Tevyaw, Arne Winguth, Cornelia Winguth, Robert S. Nicoll, Malcom Bocking, James L. Crowley

Department of Earth and Atmospheric Sciences: Faculty Publications

Past studies of the end-Permian extinction (EPE), the largest biotic crisis of the Phanerozoic, have not resolved the timing of events in southern high-latitudes. Here we use palynology coupled with high-precision CA-ID-TIMS dating of euhedral zircons from continental sequences of the Sydney Basin, Australia, to show that the collapse of the austral Permian Glossopteris flora occurred prior to 252.3 Ma (~370 kyrs before the main marine extinction). Weathering proxies indicate that floristic changes occurred during a brief climate perturbation in a regional alluvial landscape that otherwise experienced insubstantial change in fluvial style, insignificant reorganization of the depositional surface, and no …

Multi-Proxy Constraints On The Significance Of Covariant Δ13c Values In Carbonate And Organic Carbon During The Early Mississippian, Amanda M. Oehlert, Peter K. Swart, Gregor P. Eberli, Samantha Evans, Tracy D. Frank

Department of Earth and Atmospheric Sciences: Faculty Publications

This study investigates the covariation between carbonate and organic δ¹³C values in a proximal to distal transect of four outcrops in the Madison Limestone in the Western United States Rockies, combined with δ³⁴S values of carbonate associated sulphate, the concentration of acid-insoluble material and measurements of total organic carbon. These new geochemical datasets not only allow for an evaluation of carbon isotope covariance during one of the largest perturbations to the global carbon cycle over the past 550 Myr, but also constrain the cause of the excursion in carbonate δ¹³C values. The results support …

Cut, Fill, Repeat: Slot Canyons Of Dry Fork, Kane County, David Loope

Department of Earth and Atmospheric Sciences: Faculty Publications

The slot canyons of southern Utah (figure 1) have become popular destinations for hikers, climbers, and photographers. For most of these canyons, the geology is simple: sediment carried by flowing water abrades a thick, homogeneous sandstone. As time passes, the rate of down-cutting is rapid compared to the rate of cliff retreat. End of story. The strange abundance and configuration of the slot canyons along Dry Fork Coyote (a tributary of Coyote Gulch and the Escalante River), however, have a convoluted geologic history that is climate-driven and involves canyon cutting, canyon filling, and more canyon cutting.

Hexagonal Fracture Patterns On Navajo Sandstone Crossbeds At Yellow Knolls, Washington County, David Loope

Department of Earth and Atmospheric Sciences: Faculty Publications

At this geosite, the main features of interest—remarkably uniform and beautiful fracture patterns dominantly composed of linked hexagons (fi gures 1 and 2)—are present on outcrops of the Jurassic Navajo Sandstone. Th e Navajo was deposited by large, southward- migrating desert dunes about 200 million years ago, but the fractures that defi ne the hexagons here are just a surfi cial veneer less than 20 inches (half a meter) deep. Th e fractures are a weathering phenomenon that developed under climate conditions similar to today’s. Steep thermal gradients develop in the sandstone because it is exposed to solar radiation and …

Plant Root Systems Preserved In The Permian Cedar Mesa Sandstone At Moki Dugway, Southeastern Utah, David Loope

Department of Earth and Atmospheric Sciences: Faculty Publications

Rooted green plants represent the base of the food chain for most terrestrial ecosystems, but, compared to animal burrows, root systems are relatively rarely recognized in ancient sedimentary rocks. Plant roots that penetrate unconsolidated sand dunes, especially those containing not only quartz grains, but also abundant grains of calcite (CaCO₃), are commonly replaced by fine crystals of calcite (Klappa, 1980). These structures (known by geologists as rhizoliths from the Greek for “root rock”) are one form of calcite cemented soil and sediment called caliche (Figure 1). Caliche crystallizes well above the water table and its calcite crystals are …