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Articles 61 - 90 of 148

Full-Text Articles in Geology

On The Importance Of Stratigraphic Control For Vertebrate Fossil Sites In Channel Islands National Park, California, Usa: Examples From New Mammuthus Finds On San Miguel Island, Jeffrey S. Pigati, Daniel R. Muhs, John P. Mcgeehin Sep 2016

On The Importance Of Stratigraphic Control For Vertebrate Fossil Sites In Channel Islands National Park, California, Usa: Examples From New Mammuthus Finds On San Miguel Island, Jeffrey S. Pigati, Daniel R. Muhs, John P. Mcgeehin

United States Geological Survey: Staff Publications

Quaternary vertebrate fossils, most notably mammoth remains, are relatively common on the northern Channel Islands of California. Well-preserved cranial, dental, and appendicular elements of Mammuthus exilis (pygmy mammoth) and Mammuthus columbi (Columbian mammoth) have been recovered from hundreds of localities on the islands during the past half-century or more. Despite this paleontological wealth, the geologic context of the fossils is described in the published literature only briefly or not at all, which has hampered the interpretation of associated 14C ages and reconstruction of past environmental conditions. We recently discovered a partial tusk, several large bones, and a tooth enamel plate …


Stratigraphy Of The Upper Devonian-Lower Mississippian Michigan Basin: Review And Revision With An Emphasis On The Ellsworth Petroleum System, Bryan J. Currie Aug 2016

Stratigraphy Of The Upper Devonian-Lower Mississippian Michigan Basin: Review And Revision With An Emphasis On The Ellsworth Petroleum System, Bryan J. Currie

Masters Theses

Compression associated with the formation of the Transcontinental Arch and the Acadian Mountains initiated subsidence in the Michigan Basin and lead to a depositional switch in the Michigan Basin from an oxic shallow-water carbonate platform (Traverse Group and Squaw Bay Limestone) to a deep anaerobic sea floor and the beginning of Upper Devonian Antrim Shale. The vertical distribution of the different Upper Devonian-Lower Mississippian formations and members demonstrates large scale cycles of anaerobic-dysaerobic transitions attributed fluctuations in sea-level, different rates of subsidence and sediment influx triggered by different orogenic events to.

The regional understanding and the distribution of the different …


Sedimentology And Stratigraphy Of The Middle Jurassic Preuss Sandstonein Northern Utah And Eastern Idaho, Preston Scott Cook Jun 2016

Sedimentology And Stratigraphy Of The Middle Jurassic Preuss Sandstonein Northern Utah And Eastern Idaho, Preston Scott Cook

Theses and Dissertations

The purpose of this study is to analyze the sedimentology and stratigraphy of the Middle Jurassic Preuss Sandstone and re-evaluate past sedimentological interpretations. The Preuss is located in northern Utah, western Wyoming and eastern Idaho and is stratigraphically equivalent to the Entrada Sandstone, which is Callovian in age (Dossett et al., 2014). This study is the first attempt at 1) a sequence stratigraphic framework, 2) a petroleum system analysis and 3) an extraterrestrial analog study for the Preuss. This study frames the Preuss within three broad facies groups: marine, coastal and terrestrial. The marine group includes the open marine and …


A History Of African And South American Basins, Rebecca A. Bobick Apr 2016

A History Of African And South American Basins, Rebecca A. Bobick

Open Access Theses

As hydrocarbon development in Africa and South America continues to expand, understanding the geologic evolution as well as the geologic symmetry of each of the continent's coastal basins grows increasingly important. Unfortunately, there's currently no comprehensive database that contains the stratigraphic record, depositional environments, and tectonic evolution available for either Africa or South America. Therefore, the goal of my research is to create an extensive datapack and guide booklet for Africa's major sedimentary basins, complete the South America datapack that's currently being constructed, and correlate the western African conjugate basins to the eastern South American conjugate basins. To accomplish this, …


Depositional Facies And Sequence Stratigraphy Of Niagaran-Lower Salina Reef Complex Reservoirs Of The Guelph Formation, Michigan Basin, Matthew J. Rine Dec 2015

Depositional Facies And Sequence Stratigraphy Of Niagaran-Lower Salina Reef Complex Reservoirs Of The Guelph Formation, Michigan Basin, Matthew J. Rine

Masters Theses

Hydrocarbon reservoirs in the Niagara-Lower Salina Reef Complex in the Michigan Basin have been extensively studied since the early 1960’s. These reservoirs host an immense hydrocarbon resource, existing as closely-spaced, highly-compartmentalized reservoirs that have produced >500 million barrels of oil and 2.9 trillion cubic feet of natural gas. Previous studies depict these “pinnacle reefs” as tall, symmetrical towers with a random distribution of facies. This study utilizes abundant core data (32 cores, 20-acre spacing), thin-section petrography, and petrophysical wire-line logs to reconstruct the geometry, facies distributions, depositional history, and sequence stratigraphy of the Columbus III Reef Complex within the Southern …


Geological Controls On Stratigraphy And Sedimentation Of The Mississippian Marshall Formation, Michigan Basin, U.S.A., Joseph G. Adducci Aug 2015

Geological Controls On Stratigraphy And Sedimentation Of The Mississippian Marshall Formation, Michigan Basin, U.S.A., Joseph G. Adducci

Masters Theses

An understanding of regional orogenic, climatic, and eustatic processes is critical to the interbasinal correlation of Paleozoic strata in eastern North America. Tectonic activity associated with the culmination of Appalachian Orogenic events has been shown to have regional influence on paleostructure and sediment dispersal in the Appalachian foreland basin and adjacent intracratonic Illinois and Michigan basins. The culmination of the Acadian Orogeny at the end of the Devonian represents the beginning of a period of general tectonic quiescence extending throughout the early and middle Mississippian in eastern North America. Early Mississippian strata in the Michigan basin is distinctive and marks …


Unraveling Controls On Fracture Stratigraphy In Carbonates: The Influence Of Regional Stress, Mechanical Properties, And Diagenesis, Matthew H. Peppers May 2015

Unraveling Controls On Fracture Stratigraphy In Carbonates: The Influence Of Regional Stress, Mechanical Properties, And Diagenesis, Matthew H. Peppers

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Fracture characteristics analyzed from outcrops provide key insights into the migration pathways of subsurface hydrocarbons, and allow for a detailed understanding of the tectonic history in an area. This study looks to assess the impacts that various controlling factors have on the development of fracture characteristics. To complete this objective, a succession of Ordovician to Mississippian rocks was examined. The logged section includes the Cotter Dolomite, Chattanooga Shale, St. Joe Formation, and the Boone Formation (subdivided into informal Upper and Lower members). Located in northwestern Arkansas and southwestern Missouri, data were collected from roadcut exposures along Highway 71. Collected fracture …


Sequence Stratigraphy, Depositional Environments And Geochemistry Of The Middle Cambrian Bloomington Formation In Northern Utah, Christopher Ryan Jensen May 2015

Sequence Stratigraphy, Depositional Environments And Geochemistry Of The Middle Cambrian Bloomington Formation In Northern Utah, Christopher Ryan Jensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Bloomington Formation (~425 m thick) is a latest Middle Cambrian (~506.5-505 Ma.), mixed warm water, carbonate and shale unit on the Cordilleran passive margin in northern Utah and southern Idaho. The Hodges Shale and Calls Fort Shale Members are shale dominated and the Middle Limestone Member is a thick carbonate. Fossil diversity and abundance is surprisingly low for a Middle Cambrian carbonate/shale formation. Present, however, are 10-50 cm thrombolite mud mounds, associated with Girvanella oncoliths. These mud mounds represent shallow water carbonates that experienced a small flooding event that gives the mud mounds time and proper conditions to build …


Holocene Sedimentology And Stratigraphy Of Coastal Sediments In An Arid Climate, Al Qahmah, Southern Red Sea, Saudi Arabia, Abdullah Ibrahim Nabhan Jan 2015

Holocene Sedimentology And Stratigraphy Of Coastal Sediments In An Arid Climate, Al Qahmah, Southern Red Sea, Saudi Arabia, Abdullah Ibrahim Nabhan

Doctoral Dissertations

"Holocene sedimentary deposits in Al Qahmah coast, southern Red Sea, in Saudi Arabia have been accumulated on an arid siliciclastic coast in a rift tectonic setting. This study provides a detail interpretation and analysis of sedimentary facies, stratigraphy, depositional environment, and major geological processes. Two studies have been undertaken. First, petrological study of composition and texture of modern sediments and facies mapping delineate facies distribution and mechanisms of sediment transport and deposition. A unique suite of complex riverine, wave, tidal, wind, and chemical and biological processes affect the composition, texture, and distribution of the facies. Second, the depositional environments of …


The Geologic Implications Of The Factors That Affected Relative Sea-Level Positions In South Carolina During The Pleistocene And The Associated Preserved High-Stand Deposits, William Richardson Doar Iii Dec 2014

The Geologic Implications Of The Factors That Affected Relative Sea-Level Positions In South Carolina During The Pleistocene And The Associated Preserved High-Stand Deposits, William Richardson Doar Iii

Theses and Dissertations

This work utilizes the current understanding of South Carolina geology to provide a stratigraphic review of the late-Pliocene and Pleistocene marine deposits. Almost two centuries of recorded geological study includes geomorphic and stratigraphic units that were described, proposed, revised, abandoned, and revived. Along with the history of the age assignments, changes in geological time scales, and the changes in the understanding of geological concepts, this review is necessary because two concurrent and conflicting stratigraphies exist for late-Pliocene and Pleistocene marine sediments that record multiple sea-level transgressions that were more often destructive than constructive. The result, when tested against existing geological …


Sedimentological And Stratigraphic Study Of A Falling-Stage Delta Complex In The Upper Cretaceous (Turonian) Ferron Sandstone Member Of The Mancos Shale, South-Central Utah, Usa, Fares Alaboud Jun 2014

Sedimentological And Stratigraphic Study Of A Falling-Stage Delta Complex In The Upper Cretaceous (Turonian) Ferron Sandstone Member Of The Mancos Shale, South-Central Utah, Usa, Fares Alaboud

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The character and distribution of lithofacies in falling-stage deltas are incompletely documented. This paper presents a sedimentological and stratigraphic evaluation of a superbly-exposed interval of Cretaceous deltaic strata that are believed to be of falling stage origin. The studied interval forms part of the Upper Cretaceous (Turonian) Ferron Sandstone Member of the Mancos Shale in the southernmost Henry Mountains Basin of south-central Utah, USA. The interval of interest is exposed in three dimensions over a 20 km2 area in a series of canyon walls. Observed facies include fine-grained mudrocks (offshore basin), mudrocks with thinly interlaminated sandstone (prodelta), thinly interbedded …


Subsurface Sequence Stratigraphy And Reservoir Characterization Of The Mississippian Limestone (Kinderhookian To Meramecian), South Central Kansas And North Central Oklahoma, Thomas Cahill May 2014

Subsurface Sequence Stratigraphy And Reservoir Characterization Of The Mississippian Limestone (Kinderhookian To Meramecian), South Central Kansas And North Central Oklahoma, Thomas Cahill

Graduate Theses and Dissertations

Both conventional and unconventional Mississippian reservoirs in the mid-continent are largely comprised of chert-rich carbonates of Osagean and Meramecan age. The conventional reservoir target is the Mississippian "chat," a high porosity, chert residuum interval found immediately beneath the Mississippian-Pennsylvanian unconformity. The unconventional reservoir target occurs in the lower porosity, cherty, mud-rich intervals that occur in the lower portion of the Mississippian succession.

There has been considerable debate surrounding the sequence stratigraphic interpretations, depositional models, and formation names applied to the reservoir intervals within the subsurface. Another major issue with regard to the subsurface is the stratigraphic position and origin of …


Geologic Setting And Stratigraphy Of The Ziegler Reservoir Fossil Site, Snowmass Village, Colorado, Jeffrey S. Pigati, Ian M. Miller, Kirk R. Johnson, Jeffrey S. Honke, Paul E. Carrara, Daniel R. Muhs, Gary Skipp, Bruce Bryant Jan 2014

Geologic Setting And Stratigraphy Of The Ziegler Reservoir Fossil Site, Snowmass Village, Colorado, Jeffrey S. Pigati, Ian M. Miller, Kirk R. Johnson, Jeffrey S. Honke, Paul E. Carrara, Daniel R. Muhs, Gary Skipp, Bruce Bryant

United States Geological Survey: Staff Publications

The geologic setting of the Ziegler Reservoir fossil site is somewhat unusual—the sediments containing the Pleistocene fossils were deposited in a lake on top of a ridge. The lake basin was formed near Snowmass Village, Colorado (USA) when a glacier flowing down Snowmass Creek Valley became thick enough to overtop a low point in the eastern valley wall and entered the head of Brush Creek Valley. When the glacier retreated at about 155–130 ka, near the end of Marine Oxygen Isotope Stage 6, the Brush Creek Valley lobe left behind a moraine that impounded a small alpine lake. The lake …


Loess Records, Daniel R. Muhs, Stephen R. Cattle, Onn Crouvi, Denis-Didier Rousseau, Jimin Sun, Marcelo A. Zárate Jan 2014

Loess Records, Daniel R. Muhs, Stephen R. Cattle, Onn Crouvi, Denis-Didier Rousseau, Jimin Sun, Marcelo A. Zárate

United States Geological Survey: Staff Publications

Loess is aeolian sediment, dominated by silt-sized particles, that is identifiable in the field as a distinct sedimentary body. It covers a significant portion of the land surface of the Earth and as such constitutes one of the most important archives of long-term dust deposition. Large tracts of loess cover Europe, Asia, South America, and North America, and smaller loess bodies are found covering parts of Africa, the Middle East, New Zealand, and Australia. Loess thickness, particle size, and carbonate content decrease downwind from sources, trends that are powerful tools for reconstructing paleowinds. Many loess sections consist of relatively thick …


Late Mississippian (Chesterian) Through Early Pennsylvanian (Atokan) Strata, Michigan Basin, U.S.A., Shannon M. Towne Apr 2013

Late Mississippian (Chesterian) Through Early Pennsylvanian (Atokan) Strata, Michigan Basin, U.S.A., Shannon M. Towne

Masters Theses

Over 2,000 linear feet of core material was analyzed to evaluate the stratigraphy and basin evolution of Carboniferous strata in the Michigan basin. Rock units were evaluated on the basis of lithofacies type, contact relationships, and existing regional geologic interpretations. The recovery of three distinct pollen and spore assemblages from core confirms the timing of deposition during the Late Mississippian Chesterian and Early-Middle Pennsylvanian Morrowan and Atokan regional stages within the Michigan basin.

The deposition of a marine carbonate succession with significant interstratified quartz sandstone occurred during the Chesterian regional stage. The Bayport interval (Bayport Limestone) is composed of seven …


Integrating Depositional Facies And Sequence Stratigraphy In Characterizing Unconventional Reservoirs: Eagle Ford Shale, South Texas, Seth Jordan Workman Apr 2013

Integrating Depositional Facies And Sequence Stratigraphy In Characterizing Unconventional Reservoirs: Eagle Ford Shale, South Texas, Seth Jordan Workman

Masters Theses

The Mid-to-Late Cretaceous Eagle Ford Shale of South Texas is a mixed siliciclastic/carbonate, unconventional resource play with considerable oil and natural gas. Characterization of Eagle Ford reservoir quality and potential is made difficult by complex, small-scale heterogeneities.

The limited availability of subsurface data constrains previous subsurface Eagle Ford investigations. As a result, the internal variability of depositional facies and reservoir attributes remain poorly understood for these Eagle Ford rocks.

This investigation incorporates a representative group of four Eagle Ford cores, and core data, from within the current play area in order to: 1) determine facies successions, 2) establish a hierarchal …


Analysis Of Depositional Facies And Geological Controls On Reservoir Quality In Lower-Middle Devonian Sylvania Sandstone, Midland County, Michigan, Katherine A. Pollard Apr 2013

Analysis Of Depositional Facies And Geological Controls On Reservoir Quality In Lower-Middle Devonian Sylvania Sandstone, Midland County, Michigan, Katherine A. Pollard

Masters Theses

The early-Middle Devonian Sylvania “Sandstone” is considered a target for potential CO2 geosequestration. In order to develop geostatic models for CO2 injection simulations, controls on reservoir properties must be addressed. The three objectives of this study involve: 1) develop an overview of depositional lithofacies and their vertical stacking relationships, 2) determine fluid sources and controls of diagenesis (dolomitization and silicification), and 3) examine geological controls on the distribution and character of reservoir facies.

The grossly transgressive Sylvania-Bois Blanc interval is a complex lithologic assemblage. Sylvania “Sandstone” strata transition from high energy, subtidal to lower-intertidal mixed carbonate-siliciclastic facies to …


Physical And Sequence Stratigraphy Of The Late Cretaceous Chispa Summit Formation, Jeff Davis County, Texas, Patrick Thomas Dietzel Jan 2013

Physical And Sequence Stratigraphy Of The Late Cretaceous Chispa Summit Formation, Jeff Davis County, Texas, Patrick Thomas Dietzel

Open Access Theses & Dissertations

The Late Cretaceous Chispa Summit Formation of west Texas has historically been of interest to the petroleum industry; with new technologies, this old, uneconomical play could prove significant, if not for energy resources, for educational purposes, but little work has been conducted on the formation. The Eagle Ford Formation of southern Texas is time equivalent to the Chispa Summit Formation and is a highly prolific hydrocarbon resource.

Located in western Jeff Davis County, Texas, the Chispa Summit Formation consists of marine shales interbedded with limestone beds and sporadically located siliciclastic beds, measuring a total of 610 m at the type …


Chronology And Provenance Of Last-Glacial (Peoria) Loess In Western Iowa And Paleoclimatic Implications, Daniel R. Muhs, E. Arthur Bettis Iii, Helen M. Roberts, Stephen S. Harlan, James B. Paces, Richard L. Reynolds Jan 2013

Chronology And Provenance Of Last-Glacial (Peoria) Loess In Western Iowa And Paleoclimatic Implications, Daniel R. Muhs, E. Arthur Bettis Iii, Helen M. Roberts, Stephen S. Harlan, James B. Paces, Richard L. Reynolds

United States Geological Survey: Staff Publications

Geologic archives show that the Earth was dustier during the last glacial period. One model suggests that increased gustiness (stronger, more frequent winds) enhanced dustiness. We tested this at Loveland, Iowa, one of the thickest deposits of last-glacial-age (Peoria) loess in the world. Based on K/Rb and Ba/Rb, loess was derived not only from glaciogenic sources of the Missouri River, but also distal loess from non-glacial sources in Nebraska. Optically stimulated luminescence (OSL) ages provide the first detailed chronology of Peoria Loess at Loveland. Deposition began after ~27 ka and continued until ~17 ka. OSL ages also indicate that mass …


Detrital Carbonates In A Sequence Stratigraphic Framework: An Example From The Furongian Slope Environment In The Hot Creek Range Of Central Nevada, Leon Taufani Dec 2012

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 …


Determining The Motion And Location Of The Frenchman Mountain Fault, Las Vegas, Nevada: A Paired Basin Analysis And Structural Analysis, Laura Margaret Eaton Aug 2012

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 …


Sequence Stratigraphy And Depositional Systems Of The Mansfield Sand, Upper Atoka Formation, Arkoma Basin, Arkansas, Scott Cherry Aug 2012

Sequence Stratigraphy And Depositional Systems Of The Mansfield Sand, Upper Atoka Formation, Arkoma Basin, Arkansas, Scott Cherry

Graduate Theses and Dissertations

The Mansfield sand is an informally named member of the Pennsylvanian Atoka Formation in Arkansas. Once a productive gas reservoir, the Mansfield is situated in a double plunging anticline in the southern portion of the Arkoma Basin. The formation is internally composed of sandstone units ranging in thickness from tens of feet to over a hundred feet interbedded with shale units ranging in thickness from several tens of feet to hundreds of feet. Previous studies have focused on the stratigraphy of the lower and middle Atoka. A detailed subsurface study of the stratigraphic framework of the Mansfield sand was conducted …


Stratigraphy And Provenance Of Shallow Sandstones Endountered In Wells In Townships 9 And 10 North, Ranges 6 And 7 West, White County, Arkansas, Lacie Knight May 2012

Stratigraphy And Provenance Of Shallow Sandstones Endountered In Wells In Townships 9 And 10 North, Ranges 6 And 7 West, White County, Arkansas, Lacie Knight

Graduate Theses and Dissertations

Paleozoic formations in western Arkansas have been well-studied; however, they are not well-understood in the eastern part of the state. The study area encompasses Townships 9. N. and 10. N., Ranges 6. W. and 7. W. in north-central White County, Arkansas. This area is at the intersection of four physiographic provinces as defined by the Arkansas Geologic Survey- the Ozark Plateaus, the Arkansas River Valley, the Ouachita Mountains, and the Mississippi Alluvial Plain. Interpretations of the surface unit in the area disagree. The Arkansas Geologic Map shows that the Morrowan Hale Formation crops out in the area; however, various petroleum …


Holocene Arroyo Cut And Fills Cycles, South-Central Washington, Matthew Ian Durkee Jan 2012

Holocene Arroyo Cut And Fills Cycles, South-Central Washington, Matthew Ian Durkee

All Master's Theses

Ephemeral streams have cut deeply incised arroyos into alluvial and eolian sediments in many of the watersheds within the Yakima Training Center (YTC) military reservation, south-central Washington. The most recent channel incision episode along Selah Creek is primarily attributed to multiple failures of an irrigation reservoir dam during the winters of 1909 and 1910. The modern arroyo exposed evidence of at least one previous episode of arroyo incision to a depth of ~4 m that occurred just prior to 1530- 1340 cal yr BP. Filling of this paleo-arroyo with fine to coarse grained sand ceased between 650-103 cal yr BP. …


Three Geologic Cross Sections Across Portions Of Eastern Nebraska Showing Quaternary Lithologic Units And Stratigraphy Of Uppermost Bedrock, Jesse T. Korus, Dana Divine, P. R. Hanson, J. S. Dillon Jan 2012

Three Geologic Cross Sections Across Portions Of Eastern Nebraska Showing Quaternary Lithologic Units And Stratigraphy Of Uppermost Bedrock, Jesse T. Korus, Dana Divine, P. R. Hanson, J. S. Dillon

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Stratigraphic, Microfossil, And Geochemical Analysis Of The Neoproterozoic Uinta Mountain Group, Utah: Evidence For A Eutrophication Event?, Dawn Schmidli Hayes May 2011

Stratigraphic, Microfossil, And Geochemical Analysis Of The Neoproterozoic Uinta Mountain Group, Utah: Evidence For A Eutrophication Event?, Dawn Schmidli Hayes

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Several previous Neoproterozoic microfossil diversity studies yield evidence for a relatively sudden biotic change prior to the first well‐constrained Sturtian glaciations. In an event interpreted as a mass extinction of eukaryotic phytoplankton followed by bacterial dominance, diverse assemblages of complex acritarchs are replaced by more uniform assemblages consisting of simple leiosphaerid acritarchs and bacteria. Recent data from the Chuar Group of the Grand Canyon (770‐742 Ma) suggest this biotic change was caused by eutrophication rather than the direct effects of Sturtian glaciation; evidence includes total organic carbon increases indicative of increasing primary productivity followed by iron speciation values that suggest …


An Integrated Geological And Geophysical Study Of The Fresh And Brackish Water Boundary In The Hueco Bolson, West Texas, Sandy Stephanie Marrufo Jan 2011

An Integrated Geological And Geophysical Study Of The Fresh And Brackish Water Boundary In The Hueco Bolson, West Texas, Sandy Stephanie Marrufo

Open Access Theses & Dissertations

The Hueco Bolson in West Texas is located in the Rio Grande rift basin and provides water to El Paso County, Texas and Juarez, Mexico. El Paso Water Utilities (EPWU) drilled many wells up to 1000 ft (305) m into this aquifer, which provide 40% of El Paso's water supply. Stratigraphy and sedimentation in active extensional basins have received little study because they are usually buried and this research helped document these processes. The study area within the West Texas region of the Hueco Bolson Aquifer (HBA) lies within a transition zone between the fresh and brackish water sections of …


Stratigraphy, Sedimentology, And Ichnology Of The Upper Cretaceous Frontier Formation In The Alkali Anticline Region, Bighorn County, Wyoming, Charles K. Clark May 2010

Stratigraphy, Sedimentology, And Ichnology Of The Upper Cretaceous Frontier Formation In The Alkali Anticline Region, Bighorn County, Wyoming, Charles K. Clark

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The Upper Cretaceous Frontier Formation was studied along two strike-parallel cliff-lines in the Alkali Anticline region of the northeastern Bighorn Basin, Bighorn County, Wyoming. The unit comprises up to 145 m of mudrock, sandstone, conglomerate, and volcanic fallout sediments deposited along the western margin of the Cretaceous Western Interior Seaway (KWIS) in the mid- to late-Cenomanian. Eighteen facies, comprising six facies associations are identified from physical and biogenic sedimentary features. Sediments were deposited in open marine offshore to shoreface and subaqueous deltaic to delta platform environments. The observed trace fossil suites record departures from the archetypal ichnofacies. Such departures record …


A Sequence Stratigraphic And Isotopic Study Of Uppermost Pennsylvanian–Lower Permian Carbonate Strata, Orogrande Basin, New Mexico, Jesse Koch Apr 2010

A Sequence Stratigraphic And Isotopic Study Of Uppermost Pennsylvanian–Lower Permian Carbonate Strata, Orogrande Basin, New Mexico, Jesse Koch

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Determining how the tropics respond to glaciation is important for improving our global understanding of icehouse worlds. The impetus behind this study is to identify the far-field impacts of Gondwanan glaciation during the Early Permian. Impacts including climate and sea-level change should be evident in sensitive carbonate systems, such as the upper Paleozoic paleotropical strata in the Orogrande Basin. A sequence stratigraphic and stable isotopic approach is used to examine the effects of late Paleozoic climate change in the Orogrande Basin during the acme and subsequent demise of the late Paleozoic ice age.

Sequence stratigraphic analysis suggests the occurrence of …


The Biscayne Aquifer Of Southeastern Florida, Kevin J. Cunningham, Lee J. Florea Jan 2009

The Biscayne Aquifer Of Southeastern Florida, Kevin J. Cunningham, Lee J. Florea

Earth, Environmental, and Atmospheric Sciences Faculty Publications

No abstract provided.