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Stephen F. Austin State University

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Articles 91 - 109 of 109

Full-Text Articles in Geology

Clastic Sinkhole And Pseudokarst Development In East Texas, Kevin W. Stafford, Melinda G. Shaw-Faulkner, Wesley A. Brown Jan 2013

Clastic Sinkhole And Pseudokarst Development In East Texas, Kevin W. Stafford, Melinda G. Shaw-Faulkner, Wesley A. Brown

Faculty Publications

Pseudokarst development in East Texas is controlled primarily by a combination of suffosion and preferential flow paths, often creating small ephemeral sinkholes but occasionally persistent features develop in more indurated facies. Pseudokarst occurs in Claiborne (Eocene) strata in Angelina, Cherokee, Nacogdoches, Panola, Rusk, San Augustine and Shelby counties. Strata consist of interbedded fine- and coarse-grained clastics with variable cementation and associated permeabilities.


Caves And Karst Hydrology Of The Mariana Islands (Abstract), Kevin W. Stafford Jan 2013

Caves And Karst Hydrology Of The Mariana Islands (Abstract), Kevin W. Stafford

Faculty Publications

Abstract Attached


Petrology Of Proterozoic To Tertiary Rocks In The Southern Burro Mountains, Nm: Insights Into Mazatzal To Basin And Range Magmatism And Tectonics, Theda Strickler Apr 2012

Petrology Of Proterozoic To Tertiary Rocks In The Southern Burro Mountains, Nm: Insights Into Mazatzal To Basin And Range Magmatism And Tectonics, Theda Strickler

Undergraduate Research Conference

Analysis of thin sections from the Wind Mountain quadrangle, Burro Mountains, NM, near the Tyrone copper mine, reveals a complex geologic history. Rock samples collected in the study area were cut using a rock saw and thin sections were prepared and analyzed to determine mineral content and fabric patterns. The oldest rocks in the study area are strongly metamorphosed and locally mylonitized Proterozoic quartzofeldspathic gneisses and amphibolites of Mazatzal affinity. Mineralogical indications of shearing correlate with shear zones observed during field mapping in the area. Another set of samples are of younger Proterozoic granites and metagranites that intruded the country …


Modeling Regional Radicarbon Trends: A Case Study From The East Texas Woodland Period, Robert Z. Selden Jr. Jan 2012

Modeling Regional Radicarbon Trends: A Case Study From The East Texas Woodland Period, Robert Z. Selden Jr.

CRHR: Archaeology

The East Texas Radiocarbon Database contributes to an analysis of tempo and place for Woodland era (~500 BC–AD 800) archaeological sites within the region. The temporal and spatial distributions of calibrated 14C ages (n = 127) with a standard deviation (ΔT) of 61 from archaeological sites with Woodland components (n = 51) are useful in exploring the development and geographical continuity of the peoples in east Texas, and lead to a refinement of our current chronological understanding of the period. While analysis of summed probability distributions (SPDs) produces less than significant findings due to sample size, they are used …


Spring Hydrology Of Colorado Bend State Park, Central Texas, Kevin W. Stafford, Melinda G. Shaw-Faulkner, Jessica L. Deleon Apr 2011

Spring Hydrology Of Colorado Bend State Park, Central Texas, Kevin W. Stafford, Melinda G. Shaw-Faulkner, Jessica L. Deleon

Faculty Publications

Karst development in Ellenburger carbonates near Colorado Bend State Park in central Texas exhibits complex polygenetic origins, with porosity development dominated by an early hypogene phase that has subsequently been overprinted to varying degrees by epigene processes. Quarterly physicochemical and continuous thermal monitoring analyses of eight springs in the study area indicate that modern groundwater flow paths are highly variable. Springs exhibit patterns that range from shallow, distributed recharge into diffuse-flow dominated systems, to focused recharge into well-connected conduit systems, to deep-circulation systems that equilibrate with bedrock. All springs, except Sulphur Spring, exhibit physicochemical characteristics indicative of proximal epigenic groundwater …


Thermal Characterization Of The Ellenberger Karst Springs, Colorado Bend State Park, Texas [Abstract], Sherri Dornak, Katie Mitchell, Jessica De Leon, Kevin W. Stafford Jan 2011

Thermal Characterization Of The Ellenberger Karst Springs, Colorado Bend State Park, Texas [Abstract], Sherri Dornak, Katie Mitchell, Jessica De Leon, Kevin W. Stafford

Faculty Presentations

No abstract provided.


A Comparative Integrated Geophysical Study Of Horseshoe Chimney Cave, Colorado Bend State Park, Texas, Wesley A. Brown, Kevin W. Stafford, Melinda G. Shaw-Faulkner, Andy Grubbs Jan 2011

A Comparative Integrated Geophysical Study Of Horseshoe Chimney Cave, Colorado Bend State Park, Texas, Wesley A. Brown, Kevin W. Stafford, Melinda G. Shaw-Faulkner, Andy Grubbs

Faculty Publications

An integrated geophysical study was performed over a known cave in Colorado Bend State Park (CBSP), Texas, where shallow karst features are common within the Ellenberger Limestone. Geophysical survey such as microgravity, ground penetrating radar (GPR), direct current (DC) resistivity, capacitively coupled (CC) resistivity, induced polarization (IP) and ground conductivity (GC) measurements were performed in an effort to distinguish which geophysical method worked most effectively and efficiently in detecting the presence of subsurface voids, caves and collapsed features. Horseshoe Chimney Cave (HCC), which is part of a larger network of cave systems, provides a good control environment for this research. …


Tufa Diagenesis In A Carbonate Karst Fluvial Environment [Abstract], Janette England, Amanda Suter, Kevin W. Stafford Apr 2010

Tufa Diagenesis In A Carbonate Karst Fluvial Environment [Abstract], Janette England, Amanda Suter, Kevin W. Stafford

Faculty Presentations

No abstract provided.


Pseudokarst Of East Texas: Geomorphic Features And Evolution [Abstract], Kevin W. Stafford, Melinda G. Shaw-Faulkner, Wesley A. Brown Jan 2010

Pseudokarst Of East Texas: Geomorphic Features And Evolution [Abstract], Kevin W. Stafford, Melinda G. Shaw-Faulkner, Wesley A. Brown

Faculty Presentations

No abstract provided.


Geochemical Spatial Variability Of The Colorado River Associated With Karst Springs, Colorado Bend State Park, Central Texas [Abstract], Katie Mitchell, Sherri Dornak, Kevin W. Stafford Jan 2010

Geochemical Spatial Variability Of The Colorado River Associated With Karst Springs, Colorado Bend State Park, Central Texas [Abstract], Katie Mitchell, Sherri Dornak, Kevin W. Stafford

Faculty Presentations

No abstract provided.


Eogenetic Karst Of The Carbonate Islands Of The Northern Marianas [Abstract], Kevin W. Stafford, John W. Jenson, John E. Mylroie Jan 2009

Eogenetic Karst Of The Carbonate Islands Of The Northern Marianas [Abstract], Kevin W. Stafford, John W. Jenson, John E. Mylroie

Faculty Presentations

No abstract provided.


Ascending Water Of The Delaware Basin, Southeastern New Mexico, And Far West Texas [Abstract], Kevin W. Stafford, Raymond Nance Jan 2009

Ascending Water Of The Delaware Basin, Southeastern New Mexico, And Far West Texas [Abstract], Kevin W. Stafford, Raymond Nance

Faculty Presentations

No abstract provided.


The Pecos River Hypogene Speleogenetic Province: A Basin-Scale Karst Paradigm For Eastern New Mexico And West Texas, Usa, Kevin W. Stafford, Alexander Klimchouk, Lewis Land, Marcus O. Gary Jan 2009

The Pecos River Hypogene Speleogenetic Province: A Basin-Scale Karst Paradigm For Eastern New Mexico And West Texas, Usa, Kevin W. Stafford, Alexander Klimchouk, Lewis Land, Marcus O. Gary

Faculty Publications

Since the mid-Tertiary, lateral migration and entrenchment of the Pecos River Valley in eastern New Mexico and west Texas, USA, has significantly influenced regional groundwater flow paths, providing a focus for ascending flow in multi-storey artesian systems and a powerful potentiometric driving force for hypogene speleogenesis. Individual occurrences of hypogene karst phenomena associated with the central Pecos River Valley are widespread throughout the greater Delaware Basin region, including development in a wide range of Permian carbonate and evaporate fades. Hypogene occurrences are well-documented as far north as Santa Rosa, New Mexico and as far south as Lake Amistad, Texas. Throughout …


Undiscovered Karst Country: A New Paradigm For The Pecos Region Of Eastern New Mexico And West Texas As A Basin-Scale, Hypogene Speleogenetic Province [Abstract], Kevin W. Stafford, Lewis Land, Alexander Klimchouk Oct 2008

Undiscovered Karst Country: A New Paradigm For The Pecos Region Of Eastern New Mexico And West Texas As A Basin-Scale, Hypogene Speleogenetic Province [Abstract], Kevin W. Stafford, Lewis Land, Alexander Klimchouk

Faculty Presentations

No abstract provided.


Epigene And Hypogene Karst Manifestations Of The Castile Formation: Eddy County, New Mexico And Culberson County, Texas, Usa, Kevin W. Stafford, Raymond Nance, Laura Rosales-Lagarde, Penelope J. Boston Jul 2008

Epigene And Hypogene Karst Manifestations Of The Castile Formation: Eddy County, New Mexico And Culberson County, Texas, Usa, Kevin W. Stafford, Raymond Nance, Laura Rosales-Lagarde, Penelope J. Boston

Faculty Publications

Permian evaporites of the Castile Formation crop out over ~1,800 km2 in the western Delaware Basin (Eddy County, New Mexico and Culberson County, Texas, USA) with abundant and diverse karst manifestations. Epigene karst occurs as well-developed karren on exposed bedrock, while sinkholes dominate the erosional landscape, including both solutional and collapse forms. Sinkhole analyses suggest that more than half of all sinks are the result of upward stoping of subsurface voids, while many solutional sinks are commonly the result of overprinting of collapsed forms. Epigene caves are laterally limited with rapid aperture decreases away from insurgence, with passages developed along …


Hypogenic Speleogenesis Within Seven Rivers Evaporites: Coffee Cave, Eddy County, New Mexico, Kevin W. Stafford, Lewis Land, Alexander Klimchouk Apr 2008

Hypogenic Speleogenesis Within Seven Rivers Evaporites: Coffee Cave, Eddy County, New Mexico, Kevin W. Stafford, Lewis Land, Alexander Klimchouk

Faculty Publications

Coffee Cave, located in the lower Pecos region of southeastern New Mexico, illustrates processes of hypogenic speleogenesis in the middle Permian Seven Rivers Formation. Coffee Cave is a rectilinear gypsum maze cave with at least four stratigraphically-distinct horizons of development. Morphological features throughout the cave provide unequivocal evidence of hypogenic ascending speleogenesis in a confined aquifer system driven by mixed (forced and free) convection. Morphologic features in individual cave levels include a complete suite that defines original rising flow paths, ranging from inlets for hypogenic fluids (feeders) through transitional forms (rising wall channels) to ceiling half-tube flow features and fluid …


Hypogene Calcitization: Evaporite Diagenesis In The Western Delaware Basin, Kevin W. Stafford, Dana Ulmer-Scholle, Laura Rosales-Lagarde Jan 2008

Hypogene Calcitization: Evaporite Diagenesis In The Western Delaware Basin, Kevin W. Stafford, Dana Ulmer-Scholle, Laura Rosales-Lagarde

Faculty Publications

Evaporite calcitization within the Castile Formation of the Delaware Basin is more widespread and diverse than originally recognized. Coupled field and GIS studies have identified more than 1000 individual occurrences of calcitization within the Castile Formation outcrop area, which includes both calcitized masses (limestone buttes) and laterally extensive calcitized horizons (limestone sheets). Both limestone buttes and sheets commonly contain a central brecciated zone that we attribute to hypogene dissolution. Lithologic fabric of calcitized zones ranges from little alteration of original varved laminae to fabrics showing extensive laminae distortion as well as extensive vuggy and open cavernous porosity. Calcitization is most …


Hypogene Speleogenesis Within The Central Basin Platform: Karst Porosity In The Yates Field, Pecos County, Texas, U.S.A., Kevin W. Stafford, Fred H. Behnken, Jesse G. White Jan 2008

Hypogene Speleogenesis Within The Central Basin Platform: Karst Porosity In The Yates Field, Pecos County, Texas, U.S.A., Kevin W. Stafford, Fred H. Behnken, Jesse G. White

Faculty Publications

The Yates Unit Oil Field is located on the southeastern tip of the Central Basin Platform in eastern Pecos County, Texas. It produces from Middle Permian strata, primarily the upper San Andres Formation. Locally, the productive upper San Andres Formation is comprised of successively vertically stacked progradational shelf carbonates. Stratigraphically overlying the Yates Field reservoir, the Toborg Field produces from the uppermost Triassic and Cretaceous units. Both fields are bounded on the north and east sides by the Pecos River, which has remained entrenched in its current location since the early Tertiary. As mapped, the top of the San Andres …


Castile Evaporite Karst Potential Map Of The Gypsum Plain, Eddy County, New Mexico And Culberson County, Texas: A Gis Methodological Comparison, Kevin W. Stafford, Laura Rosales-Lagarde, Penelope J. Boston Jan 2008

Castile Evaporite Karst Potential Map Of The Gypsum Plain, Eddy County, New Mexico And Culberson County, Texas: A Gis Methodological Comparison, Kevin W. Stafford, Laura Rosales-Lagarde, Penelope J. Boston

Faculty Publications

Castile Formation gypsum crops out over ,1,800 km2 in the western Delaware Basin where it forms the majority of the Gypsum Plain. Karst development is well recognized in the Gypsum Plain (i.e., filled and open sinkholes with associated caves); however, the spatial occurrence has been poorly known. In order to evaluate the extent and distribution of karst development within the Castile portion of the Gypsum Plain, combined field and Geographic Information System (GIS) studies were conducted, which enable a first approximation of regional speleogenesis and delineate karst-related natural resources for management. Field studies included physical mapping of 50, 1-km2 sites, …