Theses and Dissertations - Department of Geological Sciences

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Depositional Environment of the Tombigbee Sand Member - Mooreville Formation Contact at Selected Outcrops in Alabama
(University of Alabama Libraries, 1968) Britton, Thomas A. Jr.; University of Alabama Tuscaloosa
A study was made of eighteen samples collected at four selected exposures of the contact of the Eutaw and Selma groups (Tombigbee Sand Member and Mooreville Formation) of Late Cretaceous (Austinian) age in central and west-central Alabama. The sediments consisted primarily of quartz sand and glauconite with muscovite and garnet secondary in abundance in the clastic fraction. Several of the samples were calcareous. Particle size analysis, fossils, and mineral content indicate the depositional environment before and after the erosional cycle between Tombigbee and Mooreville sedimentation was neritic and more likely epineritic. Certain areas of deposition may have existed as quite bays and lagoons as part of the shoreline as evidenced by the presence of glauconite and pyrite.
Biostratigraphy of the Bluffport Marl Member of the Demopolis Chalk, Cretaceous of Alabama
(University of Alabama Libraries, 1969) Newman, Harry Ellsworth, III.; University of Alabama Tuscaloosa
The Bluffport Marl Member of the Demopolis Chalk was sampled to find what lithologic and paleontologic variations occur along the strike of this unit. The Bluffport Marl Member has been traced in Alabama from Sumter County eastward into the western edge of Lowndes County, somewhat farther east than reported in earlier publications. Insolubles increase upward in the section and along strike towards the eastern extent of the Bluffport Member, implying an eastern source of clastics. The abundant invertebrate faunal assemblage of the Bluffport decreases upward in the section and to the east in direct relation to the increase in clastics. Although the Bluffport species vary in abundance at different localities, the total number of species found is nearly consistent from location to location in the lower part of the section. Morphologically, there is very little difference in the western and eastern Bluffport fauna, although there is a significant decrease in size of these assemblages toward the upper part of the section. Based on faunal changes, this increase in clastics reflects environmental conditions that were below those optimum conditions that existed in the lower and more western Bluffport section and in which these reef assemblages thrived.
Possible Origins of the Livingston Fault Zone
(University of Alabama Libraries, 1972) Schneeflock, Robert Donald Jr.; University of Alabama Tuscaloosa
The Livingston fault zone is restricted to the outcrop of the Selma Chalk of upper Cretaceous age in Sumter and Marengo Counties, Alabama. This zone is unique among Gulf Coastal Plain structures in that it contains many horsts and grabens which are bounded by reverse faults. These faults dip both to the northeast and southwest and strike North 70 degrees West with a mode for fault plane dip of 40 degrees to 45 degrees.
Criteria for Distinguishing Pleistocene(?) Alluvial Terrace Deposits from the Coker Formation in the Cottondale, Alabama, Area
(University of Alabama Libraries, 1975) Wielchowsky, Charles Carl; University of Alabama Tuscaloosa
Field, textural, mineralogical, and geochemical data were collected from the Coker Formation of Cretaceous age and the alluvial terrace deposits of Pleistocene(?) age in the Cottondale area to determine those criteria that could be used in the differentiation of these two units. It was found that no single criterion could be used with complete confidence, though a series of general criteria were developed.
Environments of Deposition of the Norphlet Formation (Jurassic) in South Alabama
(University of Alabama Libraries, 1981) Wilkerson, Richard P.; University of Alabama Tuscaloosa
In the western Gulf Coastal Plain area the Jurassic Norphlet Formation is typically characterized by non-marine and red bed lithofacies. In south Alabama the Norphlet consists of an updip conglomerate, a discontinous basal shale, red beds overlying the shale, and an upper quartzose sandstone, the Denkman Member. The Norphlet uncomformably overlies either salt, anhydrite, red beds, or Paleozoic rocks. The Smackover Formation, which overlies the Norphlet, has a sharp contact with the Norphlet over most of the study area except in parts of Mobile County.
Stratigraphy and Depositional Environments of Part of the Pennsylvanian Pottsville Formation in the Black Warrior Basin: Alabama and Mississippi
(University of Alabama Libraries, 1984) Sestak, Helen Maria; University of Alabama Tuscaloosa
Determination of depositional environments is based on the interpretation of geophysical log signatures and the distribution of sandstones and coals. Most of these data have been obtained from dual induction and density logs of wells drilled to underlying Mississippian reservoirs. The Pottsville sediments have not been a major petroleum objective; however, the numerous coal beds are a potential source of methane.
Depositional Systems in the Lower Part of the Pottsville Formation, Black Warrior Basin, Alabama
(University of Alabama Libraries, 1985) Engman, Mary Anne; University of Alabama Tuscaloosa
Three depositional systems have been defined and named within the lower Pottsville Formation in the subsurface in Alabama: (1) the Fayette-Walker barrier system, (2) the Lamar marsh-lagoon system, and (3) the Pickens-Tuscaloosa delta system. These three distinctly different depositional systems were defined on the basis of data from electric logs, sandstone isolith maps, coal distribution, and core descriptions. The Fayett-Walker barrier system is composed of a thick section of northwest-southeast trending orthoquartzitic sandstones containing thin interbeds of mudstone and rare coal beds, and extends throughout the eastern part of the study area. The Lamar marsh-lagoon system is copmosed mostly of mudstone containing few, discontinuous sandstone bodies and extends westward from the Fayette-Walker barrier system. The Pickens-Tuscaloosa delta system extends southward from the southern limit of the Fayette-Walker barrier system and the Lamar marsh-lagoon. Sparse data from the Pickens-Tuscaloosa delta system suggest a northeast-southwest-trending sandstone interbedded with mudstone and coal.
Depositional History of the Smackover Formation, Appleton Field, Escambia County, Alabama
(University of Alabama Libraries, 1992) Markland, Lisa Ann; University of Alabama Tuscaloosa
Appleton field is situated across two northwest-southeast trending, pre-Mesozoic "basement" highs near the updip limit of the Smackover Formation in the northern portion of the Conecuh embayment. Smackover deposition at Appleton field was influenced by both pre-Smackover paleotopography and variations in sea level.
Seismic interpretation and structural restoration of a seismic profile through the Southern Appalachian thrust belt under Gulf Coastal Plain sediments
(University of Alabama Libraries, 2007) Bailey, Ryan Michael; University of Alabama Tuscaloosa
In the southern part of the Appalachian thrust belt, the thrust system is buried by Gulf Coastal Plain sediments; thus, directly studying this Paleozoic thrust belt is impossible. However, multi-channel seismic data and well log data are used to explore this thrust belt. In this region, Gulf Coastal Plain sediments cover the Paleozoic thrust belt that formed during the Ouachita and Alleghenian orogeny. Due to a lack of well control and limited availability of proprietary quality seismic reflection profiles, only a few other studies interpret subsurface structures beneath the Gulf Coastal Plain (Thomas, 1973; Thomas, 1989; Bally, 1983; Hale-Erlich and Coleman, 1993). Stratigraphic thicknesses in the thrust belt were derived from the Ethel M. Koch #1 well and in the Black Warrior Basin from the James W. Sterling 17-14 well. Two additional wells, the Willis #1 and Dollarhide #1 were used to identify the depth to formation tops within the interpretation. An 84 kilometer long seismic profile was depth-converted using a sonic log from the Koch well and then projected onto a straight line perpendicular to the Appalachian thrust belt which shortened the length of the line to 78 kilometers. Five main horizons were interpreted in two way travel time and depth-converted using interval velocities derived from synthetic seismograms and the sonic log in the Koch well. A 14 kilometer zone of poorly imaged seismic data within line segment 691-1 A may be the result of high velocity material juxtaposed with the base of the Coastal Plain sediments. Two interpretations, both incorporating forward-propagating sequences, were made. The depth of the upper detachment altered the structural style of the ramp anticline on thrust 1 from a fault bend fold in interpretation #1 to a fault propagation fold in interpretation #2. Consequently, the depth of the detachment along with the fault trace of thrust 2 effected the thickness of units incorporated in thrust 2 and the thickness and number of units incorporated in thrust 3. The lengths of the units are quantitative, while the actual positions are speculative. The flexural slip method and line length balancing was used to balance the cross sections. Shortening estimates range from 23 kilometers or 29% shortening in interpretation # 1 to 19 kilometers or 26% shortening in interpretation #2.
Groundwater flow dynamics and contaminant transport to coastal waters under low recharge conditions: regional-scale study of the aquifer system underlying southern Baldwin County, Alabama
(University of Alabama Libraries, 2009) Murgulet, Dorina; Tick, Geoffrey R.; University of Alabama Tuscaloosa
This study examined the influence of drought conditions and increased hydrological stresses on the groundwater system flow dynamics, submarine groundwater discharge, and nitrate transport and discharge to the Gulf of Mexico. The results of these studies demonstrate that current stresses on the aquifer have led to significant saltwater intrusion and or direct infiltration into fresh groundwater, especially within the upper aquifers of the region. The nitrate and chloride data analyses reveal the persistent presence of multiple nitrate impacted zones within the study area. Stable isotope data support the hypothesis that nitrate in the investigated aquifers originates from the nitrification of ammonium in soils from a mixture of sources ranging from fertilizer to sewer and/or manure and that denitrification, the breakdown of nitrates to nitrogen gas, is not significant in the investigated aquifer system. Furthermore, groundwater isotope data indicates that water in the aquifer system of the study area is most likely to have originated from precipitation and soil infiltration through relatively localized recharge and that the aquifer system in the study area is highly dynamic, experiencing mixing of recent recharged waters with older, ambient groundwaters. The presence of low residence times and the absence of denitrification reveal the oxic character of this system. As a proxy for a number of contaminant types, the groundwater flow and transport model was used to simulate nitrate transport in response to variable-density groundwater flow. The simulation results indicate that in the investigated aquifer system complexities arise because groundwater flow dynamics and contaminant transport are additionally influenced by density variations that can occur from the incursion of saltwater. The model predicts that the Beach Sand and Gulf Shores Aquifers will be impacted by severe saltwater intrusion whereas the deeper 350 and 500-Foot Aquifers will experience no saltwater intrusion for the entire simulation period. Consequently, nitrate discharge to the Gulf of Mexico originates from the lower part of the aquifer system through submarine groundwater discharge. This research will serve as a tool which may be applied to other similar coastal systems for more effective management strategies.
Upper crustal shortening and forward modeling of the Himalayan fold-thrust belt along the Budhi-Gandaki river, central Nepal
(University of Alabama Libraries, 2009) Khanal, Subodha; Robinson, D. M.; University of Alabama Tuscaloosa
Geologic mapping along the Budhi-Gandaki River in central Nepal reveals 6 significant structures: 1) South Tibetan Detachment system; 2) Main Central thrust; 3) Ramgarh thrust; 4) Lesser Himalayan duplex including the Trishuli thrust; 5) Main Boundary thrust; and 6) Main Frontal thrust system. A balanced cross-section between the South Tibetan Detachment system and Main Frontal thrust reveals that the region has a minimum total shortening of 76% or 420 km. The breakdown of the accommodation of shortening on each thrust is as follows: Main Central thrust - 115 km; Ramgarh thrust - 120 km; Lesser Himalayan duplex including the Trishuli thrust - 156 km; Main Boundary thrust - 10 km; Main Frontal thrust system - 19 km. In order to validate the balanced cross-section, a reconstruction program was used to forward model the system. By moving faults with appropriate amounts of displacement over a reasonable configuration of undeformed stratigraphy from the hinterland to foreland, the deformation of the Himalayan thrust belt along the Budhi-Gandaki River cross-section is reproduced. The forward modeling program moves hanging wall rock over stationary footwall rock using each individual fault identified in the balanced crosssection. Hanging wall rock deforms as it is thrust over footwall structures. Using forward modeling, the cross-section has a shortening estimate of 412 km or 75%. The two shortening estimates are virtually identical indicating the balanced cross-section along the Budi-Gandaki River is viable and admissible.
High resolution, U/Th dated (32,000 to 11,000 years), oxygen and carbon isotope proxy climate records from a stalagmite in Desoto Caverns, Alabama, USA
(University of Alabama Libraries, 2010) Lambert, William Joseph; Aharon, Paul; University of Alabama Tuscaloosa
This study addresses the question whether speleothems from DeSoto Caverns (Childersburg, AL) can serve as archives of paleoclimate conditions for the Southeast, USA. The focus of the study involves determining present-day controls of cave water δ^18 O and δ^13 C followed by interpretation of stalagmite δ^18 O and δ^13 C variability in comparison to climate events of the past. The monitoring program involved a 3-year study of cave waters and local rainfall (Tuscaloosa, AL) during years characterized by a significant trend from wet to dry conditions. Decreasing recharge of the cave aquifer was expressed as an interannual trend of declining drip flow rates, which was punctuated by seasonal oscillations due to varying rates of evapotranspiration. Amount-weighted mean monthly rainwater δ^18 O range from -1.5 to -8.3 /, show a mean seasonal amplitude of ~4 /, and exhibit an interannual trend toward ^18 O-enrichment that I interpret as being governed by global atmospheric circulation patterns. The cave's aquifer attenuates seasonal δ^18 O variability, records 20% of rainfall's interannual ^18 O-enrichment, and is biased toward winter rainfall δ^18 O. Cave waters display strong seasonal variability in dissolved inorganic carbon (DIC) and δ^13 C, which range from 0.2 to 6.0 mM and 2.7 to -12.9 / (VPDB), respectively. The data suggest the strongest seasonal controls are cave air ventilation/stagnation and varying CO_2 fluxes through the soil horizon and epikarst. δ^13 C of active speleothems imply the precipitating aragonite captures the seasonality observed in source dripwaters and time-series δ^13 C records of stalagmites carry the imprints of drip annual means entailing climate-driven δ^13 C seasonal biases. A fossil stalagmite provided a high-resolution proxy record of rainfall variability between 31.9 and 11.3 ka. I propose a more southerly polar jet stream (PJS) promoted increased winter rainfall amounts during cold phase events while warm phases result in a higher PJS position and decreased winter rainfall. The Younger Dryas was characterized by a dramatic change in the PJS path as warm air from the Gulf of Mexico infiltrated deep into the continent's interior and substantially decreased winter rainfall. Establishment of near modern climate conditions greatly enhanced deposition rates before changes in flow paths through the epikarst prevented stalagmite deposition since 11.3 ka.
The tectonic relationships of the Hillabee Chlorite Schist and the adjacent rock units in southern Cleburne County, Alabama
(University of Alabama Libraries, 2010) Hayes-Davis, Bertram; Robinson, D. M.; University of Alabama Tuscaloosa
Southern Cleburne county Alabama contains two defined litho-tectonic blocks separated by a large displacement thrust fault. The Talladega block is composed of low grade metamorphic rocks. Sericite Phyllites and Quartzites are the main composition units. Metamorphic and tectonic events have created four defined structural events that are mapped in the block. The Hillabee Chlorite Schist, a low grade metamorphic unit lies conformable and the youngest unit in the Talladega block. Geochemical analysis indicates the origin to be in an island arc environment. The Coosa Block is thrust over the Talladega clock. The Hollins line fault is the contact between the Talladega and Coosa Blocks. The Coosa Block is composed of high grade Amphibolites facies rocks. Mica Schist with garnet and kyanite are interbedded with Amphibolites composing this block. Deformation along the Hollins line Fault creates a sercite phyllite in the high grade metamorphic Coosa Block unit. These phyllites include garnet that defines the contact between the two blocks and the placement of the Hollins line fault.
Paleoclimate reconstructions over the last century from a tropical speleothem on Niue Island, South Pacific
(University of Alabama Libraries, 2010) Murgulet, Valeriu; Aharon, Paul; University of Alabama Tuscaloosa
The study examines the question whether speleothems from Niue Island (19°00'S, 169°50'W), a large carbonate platform located at the edge of West Pacific Warm Pool, can serve as archives of hydroclimate controlled by El-Niño/Southern Oscillation (ENSO) and of catastrophic cyclones that frequent the island. Niue Island is heavily karstified, with modern and fossil speleothems hosted by coastal and inland caves. The flank margin caves on Niue are shown to be formed by the action of corrosive groundwaters on uplifted Pleistocene-age reef carbonates in a tectonically active region. The focus of this study is an actively growing stalagmite sampled from a flank margin cave (Avaiki Cave) that contains about 146 years of deposition (2002-1856 AD). The stalagmite consists of sub-annual couplets alternating between white porous calcite laminae deposited during the austral summer and dark, compact calcite laminae deposited during the austral relatively dry winter. High resolution (sub-annual) stable isotope and trace element profiles accompanied by trace element X-ray mapping were used to test the validity of ENSO-controlled hydroclimate and tropical cyclones archived in the stalagmite. The results show that interannual variability in the stalagmite d18O and d13C time series agrees well with instrumental-derived ENSO phases (El Niño and La Niña events during 1866-2002) and the sea level pressure differential (Samoa-Fiji)-based SPCZ index (SPI) that controls the interdecadal hydroclimate variability. Severe cyclones that directly impacted Niue Island over the last century are recorded by abrupt, large increases in trace element concentration values of Mg, and S accompanied by stable isotope positive excursions bearing seawater-derived signatures. Application of selected trace elements (i.e., Mg, Na, S, P) as proxies of severe storms is a novel technique that can be successfully applied in carbonate coastal areas with flank-margin caves impacted by severe cyclones. This study also demonstrates that sub-annual geochemical cycles in trace element laminae, unresolved by analytical linear transects due their complex distribution pattern, are successfully imaged by large area X-ray mapping of the stalagmite
Investigation of natural weathering processes and artificial treatment techniques in the attenuation of toxic metals from coal fly ash
(University of Alabama Libraries, 2010) Bhattacharyya, Sidhartha; Donahoe, Rona Jean; University of Alabama Tuscaloosa
Coal fly ash contains high levels of hazardous trace elements such as As, B, Cr, Mo, Ni, Se, Sr and V, which may have a negative impact on the environment due to potential leaching by acid rain and groundwater. This study seeks to develop new fly ash management techniques by determining the effects of natural weathering on trace element mobility in fly ash and by evaluating the potential use of surfactant-modified zeolite and ferrous sulfate treatment for attenuating the mobility of trace elements associated with fly ash. The effects of weathering on trace element mobility in fly ash were studied using batch competitive adsorption experiments. Fresh fly ash shows high adsorption capacity for As, V and Mo, while weathered fly ash shows high affinity for Ni, Sr, As and V. Both fresh and weathered fly ash show low adsorption capacity for Se and B. Weathering reduced the adsorption capacities of fresh fly ash for As, B, Cr, Mo, Se and V, indicating increased mobility in ash disposal environments. The effectiveness of surfactant-modified zeolite (SMZ) as a PRB material was studied using batch experiments under competitive adsorption conditions. The results showed that SMZ preferably adsorbed V, Mo and Cr over As and Se. Unmodified zeolite (UMZ) showed high adsorption capacities for Ni and Sr. Both SMZ and UMZ failed to remove B from solution. The use of SMZ as a PRB material in coal fly ash management will be limited by its low affinity for B as well as its relatively low affinity for As, Se and cations. Ferrous sulfate treatment of coal fly ash successfully reduced the mobility of oxyanionic trace elements. The unbuffered 1:30 FS treatment was highly successful; oxyanion mobility reductions were: As (24-91%), Cr (82-97%), Mo (79-100%), Se (41-87%) and V (55-100%). On the other hand, the 1:30 FS fly ash treatment failed to reduce the mobility of B, Ni and Sr. Ferrous sulfate treatment is cost effective and can be applied directly to fresh fly ash produced in electric power plants, as well as to the fly ash already placed in the ash disposal facilities.
Solute transport in aquifers characterized by small-scale preferential flowpaths: numerical modeling and field experimental studies
(University of Alabama Libraries, 2010) Bianchi, Marco; Zheng, Chunmiao; University of Alabama Tuscaloosa
Groundwater flow and solute transport are affected by the connectivity of high hydraulic conductivity (K) sediments. This research used numerical modeling and field experiments to assess and quantify connectivity and to compare alternative transport models and approaches for representing connected heterogeneity. Field work was conducted at the well-known Macrodispersion Experiment (MADE) site to investigate transport hypothesized to be controlled by a network of highly connected preferential flow paths (PFP). The research results in three self-contained, closely related, papers. The first paper evaluates the ability of different transport models to reproduce the transport behavior in a synthetic 2-D aquifer system with a high-K network embedded in a low-K matrix. Results confirm that the classical Fickian advection-dispersion model (ADM) is unable to effectively reproduce solute transport unless heterogeneity is explicitly considered. Conversely, two non-Fickian models (dual-domain mass transfer and continuous-time random walk) are able to accurately match the transport behavior using only effective parameters. However, the continuous time random walk model requires a calibrated transport velocity that is physically unrealistic. The second paper investigates flow and transport connectivity in a small block of the MADE site aquifer. K values estimated from grain size analysis of 19 cores are used to generate 3-D conditional realizations of the K field. Anomalous transport in the generated K fields is revealed by particle tracking simulations and significant connectivity is quantified by a variety of connectivity indicators. Particle paths geometry shows that flow and transport connectivity do not require fully percolating high-K clusters. The third paper presents the results of new tracer test. Breakthrough curves measured at the extraction well and at 14 multilevel sampling ports along the vertical extension of the MADE site aquifer clearly reveal the presence of a complex network of PFPs. Numerical modeling based on experimental data shows that the dual-domain mass transfer model successfully captures the characteristics of the integrated breakthrough curve at the extraction well, but it is ineffective in reproducing the concentrations observed at the multilevel sampling locations, indicating that a high-resolution characterization of the aquifer heterogeneity would be needed to fully capture 3D transport details.
A high-resolution hydroclimate record of the last three millennia from a cored stalagmite at Desoto Caverns (Alabama, USA)
(University of Alabama Libraries, 2010) Dhungana, Rajesh; Aharon, Paul; University of Alabama Tuscaloosa
Late Holocene climate changes in the Southeast USA are poorly documented due to the paucity of high-resolution paleo-records. This study provides high-resolution records of rapid hydroclimate changes in the Southeast over the last three millennia. The records are based on stable isotope rainfall proxies whose time series are constrained by precise U/Th dates from a stalagmite sampled at DeSoto Caverns. The average growth rate of the stalagmite was 149 µm/yr prior to 1400 years and it has been growing with an average growth rate of 42 µm/yr in the last 1400 years. During the past three thousand years stable isotope time series document six wet episodes (at ~ 2950, 2450, 1675, 1200, 700 and 70 years ago) alternating with six drier periods (at ~ 3100, 2800, 1900, 1500, 800 and 300 years ago). The biannually resolved 18O record agrees well with the contemporaneous SST record from the Sargasso Sea cores suggesting that changes in moisture availability in the Southeast are likely linked to subtropical North Atlantic SST variability. Power spectra analysis of the stalagmite-based oxygen isotope record reveals statistically significant periodicities at 24±1 and 36±1 year that are consistent with those observed in the contemporaneous atmospheric 14C production record. The 24 years periodicity is also consistent with the 24-year NAO Index periodicity. On the basis of our analysis we propose that the hydroclimate in the Southeast USA over the last three millennia was intimately linked to NAO variability powered by solar activity fluctuations.
Cenozoic landscape evolution of a post-compressional orogenic wedge: intermontane basin development and sediment dispersal patterns, Renova Formation, southwest Montana
(University of Alabama Libraries, 2010) Rothfuss, Jennifer L.; Weislogel, Amy L.; University of Alabama Tuscaloosa
Sediment pathways and landscape evolution are useful proxies for refining the current understanding of crustal and surficial processes that initiated Paleogene post-compressional demise of the Cordilleran orogenic wedge in southwest Montana. Basin-fill deposits of Cenozoic intermontane basins that lie along the leading edge of the Sevier fold thrust belt provide a relatively complete sedimentary record by which to evaluate surficial and crustal processes that regulate landscape evolution of a deconstructional orogen. The Paleogene Renova Formation records initial post-Laramide sediment accumulation in the intermontane basins, marking the transition from fluvial incision to sediment backfilling. Facies assemblages reflect dominance by high-energy fluvial systems and alluvial fans that record radiating dispersal from basin-bounding uplifts including as the Boulder batholith-Highland Range and Pioneer Mountains. Paleogene fluvial systems were marked by rapid fluvial aggradation, and coeval basin margin deposits preserve rapid alluvial fan progradation. Progradational and aggradational stacking patterns reflect a rapidly subsiding environment in which the rate of accommodation space generation either outpaced or was equal to the rate of sediment influx. Syndepositional volcanism coupled with rapid denudation of Sevier-Laramide highlands, some of which were bounded by normally-reactivated reverse faults, provided abundant detritus into the depositional systems during the Paleogene. Paleogene paleodrainage reconstructions are strikingly similar to Cretaceous paleodrainage reconstructions for the Kootenai, Blackleaf, and Frontier Formations (Schwartz and DeCelles, 1988), and the Beaverhead Group (Sears and Ryan, 2003), suggesting that relict Late Cretaceous paleotopography coupled with regional Sevier-Laramide structural grain, exhibited strong infrastructural control on post-Laramide drainage evolution. Two distinct Paleogene paleodrainage networks have been identified in the study area based on detrital zircon age populations and paleoflow indicators, and likely reveal the presence of two distinct and separate Paleogene fluvial systems. Altogether, data presented suggest that rugged paleotopography characterized the Southwest Montana Re-entrant of the Sevier fold thrust belt during the Paleogene. Normal-sense reactivation of Sevier thrust faults coupled with erosion by high energy fluvial and alluvial systems rapidly dissected the Cordilleran orogenic wedge.
Geochronology and pressure-temperature conditions of mid-to-lower crustal processes in a Cretaceous magmatic arc, Fiordland, New Zealand
(University of Alabama Libraries, 2010) Parker, Karen Ann; Stowell, Harold Hilton; University of Alabama Tuscaloosa
Exposures of mid-to lower-crust in Fiordland contain evidence of high temperature and pressure processes occurring beneath magmatic arcs. This thesis presents new U-Pb zircon ages that constrain emplacement of the Malaspina Pluton, Western Fiordland Orthogneiss (WFO) to 116-114 Ma and new Sm-Nd garnet ages of 115-110 Ma for partial melting of the Malaspina near the Doubtful Sound Shear Zone (DSSZ), central Fiordland. U-Pb igneous zircon ages, from west to east across Doubtful Sound (DS), are 114.2 ± 2.2, 115.4 ± 2.2, and 116.1 ± 2.4 Ma. This compares to a contact metamorphic zircon rim age of 114.8 ± 2.4 Ma for the 119.8 ± 2.9 Ma Misty Pluton. From west to east across DS, Sm-Nd garnet ages are 113.6 ± 2.5, 113.2 ± 2.8, 115.6 ± 2.6, 111.6 ± 3.1, 110.6 ± 1.9, 113.3 ± 2.6, and 111.9 ± 3.0 Ma. Hence partial melting and garnet granulite-facies metamorphism lasted ≥ 5 m.y. in DS and occurred within 5.5 m.y. of pluton emplacement. These ages compare to Sm-Nd garnet ages for garnet granulite of 126-109 Ma in northern Fiordland (Pembroke) and ca. 110 Ma in southern Fiordland (Resolution Island). Mineral assemblages in DS migmatite include Amp + Cpx + Grt + Qtz + Pl ± Bt + Rt + Ilm ± relict OPx ± relict Czo. Euhedral, peritectic garnet occurring in leucocratic veins and reaction zones, has little zoning in composition and ranges from Alm_53 Prp_27 Sps_3 Grs_17 in the west to Alm_44 Prp_36 Sps_1.5 Grs_18.5 in the east. Ilmenite with exsolved rutile and oriented exsolution needles of rutile in garnet indicate re-equilibration after high T and P. Phase diagram sections for melted WFO and thermobarometry using garnet, clinopyroxene, and plagioclase compositions indicate 700-840°C and 10.6-14.2 kbar for metamorphism on DS. Similar methods for Pembroke Granulite of >750°C at 12-16 kbar indicate diachronous widespread high P metamorphism and partial melting for this ca. 4,375 km^2 section of mid-to lower-crust with these processes occurring early in the north and later in the south (126-105) Ma.
Upper Jurassic (Oxfordian) Smackover facies characterization at Little Cedar Creek Field, Conecuh County, Alabama
(University of Alabama Libraries, 2010) Ridgway, John Grayson; Baria, Ernest A.; University of Alabama Tuscaloosa
The Upper Jurassic (Oxfordian) Smackover Formation is a shallow-marine carbonate unit in the subsurface of the U.S. Gulf Coast, spanning from south Texas to west Florida. This field case-study focuses on Little Cedar Creek Field located in southeastern Conecuh County, Alabama. The objectives of this study are to 1) construct a 3-D depositional model for the Smackover Formation at Little Cedar Creek Field; 2) establish a sequence stratigraphic framework for the construction of the depositional model; 3) characterize and map lithofacies with high resource potential based on the depositional model; and 4) demonstrate the use of the depositional model to maximize hydrocarbon recovery in the field area Little Cedar Creek Field is located near the up-dip limit of the Smackover Formation. The top of the Smackover is found at depths between 10,000 to 12,000 feet, and the formation ranges in thickness from 60 to 120 feet. The Smackover Formation overlies the Callovian-Oxfordian Norphlet Formation and underlies the Kimmeridgian Haynesville Formation. The petroleum reservoirs in Little Cedar Creek Field, unlike most Smackover fields in the eastern Gulf region, are composed predominantly of limestone, not dolomite, and do not possess a Buckner Anhydrite top seal immediately above the reservoir. Beginning from the top of the Smackover, the facies are: (S-1) Peritidal lime mudstone-wackestone; (S-2) tidal channel conglomeratic floatstone-rudstone; (S-3) peloid-ooid shoal grainstone-packstone; (S-4) subtidal lime wackestone-mudstone; (S-5) microbially-influenced packstone-wackestone; (S-6) microbial (thrombolite) boundstone; and (S-7) transgressive lime mudstone-dolostone. Production is from both the thrombolite boundstone and shoal grainstone facies, though pressure and fluid data indicate no communication between the two reservoirs. The data indicate that the microbial communities developed on subtle topographic highs overlying the transgressive lime mudstone-dolostone in a shallow-water, low-energy, hypersaline environment, parallel to the southwest-northeast trending paleoshoreline. The Conecuh Embayment, formed by the Conecuh and Pensacola Ridges to the northwest and southeast, respectively, created low-energy, tranquil conditions that promoted the development of these opportunistic microbial organisms.

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