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Articles 26131 - 26160 of 29958
Full-Text Articles in Geology
Microbial Composition Of Near-Boiling Silica-Depositing Thermal Springs Throughout Yellowstone National Park, Carrine E. Blank, Sherry L. Cady, Norman R. Pace
Microbial Composition Of Near-Boiling Silica-Depositing Thermal Springs Throughout Yellowstone National Park, Carrine E. Blank, Sherry L. Cady, Norman R. Pace
Geology Faculty Publications and Presentations
The extent of hyperthermophilic microbial diversity associated with siliceous sinter (geyserite) was characterized in seven near-boiling silica-depositing springs throughout Yellowstone National Park using environmental PCR amplification of small-subunit rRNA genes (SSU rDNA), large-subunit rDNA, and the internal transcribed spacer (ITS). We found that Thermocrinis ruber, a member of the order Aquificales, is ubiquitous, an indication that primary production in these springs is driven by hydrogen oxidation. Several other lineages with no known close relatives were identified that branch among the hyperthermophilic bacteria. Although they all branch deep in the bacterial tree, the precise phylogenetic placement of many of these lineages …
Biogeochemistry Of The Middle Rio Grande Bosque: Links Among Surface Water, Groundwater, And Sediments, Susan E. Block
Biogeochemistry Of The Middle Rio Grande Bosque: Links Among Surface Water, Groundwater, And Sediments, Susan E. Block
Earth and Planetary Sciences ETDs
The potential for water contamination is great in areas where land use is both urban and agricultural. Such land uses can load the surface water and groundwater with nutrients and toxic trace metals. Water pollution can be further increased when natural watersheds have been altered by human activities. The surface and groundwaters of the Middle Rio Grande, NM, USA are part of one such ecosystem.
Because redox processes are important controls on nutrient cycling and contaminant transport, it is vital to understand the redox zonation of an aquifer. This research has been conducted to address such biogeochemical zonation in the …
Gravity Evidence For A Larger Limpopo Belt In Southern Africa And Geodynamic Implications, Rubeni T. Ranganai, Ali Basira H. Kampunzu, Estella A. Atekwana, B. K. Paya, J. G. King, D. I. Koosimile, Edgar H. Stettler
Gravity Evidence For A Larger Limpopo Belt In Southern Africa And Geodynamic Implications, Rubeni T. Ranganai, Ali Basira H. Kampunzu, Estella A. Atekwana, B. K. Paya, J. G. King, D. I. Koosimile, Edgar H. Stettler
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The Limpopo Belt of southern Africa is a Neoarchean orogenic belt located between two older Archean provinces, the Zimbabwe craton to the north and the Kaapvaal craton to the south. Previous studies considered the Limpopo Belt to be a linearly trending east-northeast belt with a width of ∼250 km and ∼600 km long. We provide evidence from gravity data constrained by seismic and geochronologic data suggesting that the Limpopo Belt is much larger than previously assumed and includes the Shashe Belt in Botswana, thus defining a southward convex orogenic arc sandwiched between the two cratons. The 2 Ga Magondi orogenic …
Mapping The Volumetric Soil Water Content Of A California Vineyard Using High-Frequency Gpr Ground Wave Data, Susan Sharpless Hubbard, Katherine R. Grote, Yoram N. Rubin
Mapping The Volumetric Soil Water Content Of A California Vineyard Using High-Frequency Gpr Ground Wave Data, Susan Sharpless Hubbard, Katherine R. Grote, Yoram N. Rubin
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
An attempt was made to establish the utility of ground-penetrating radar (GPR) as a quick and noninvasive field tool for shallow soil water content estimates as a function of space and time. Initially, detailed studies of collocated data, with electromagnetic velocity estimates from GPR data compared to gravimetric measurements of water content and to soil testure were carried out. Using the procedures developed during the detailed studies, full grids of GPR data were collected over the entire site several times. Data obtained indicate that incorporation of multiple frequency GPR grids can provide high-resolution estimates of soil water content variations as …
Deformational Features In The Chattanooga Shale, Near Chattanooga, Tennessee, Dewayne Adarial Ponds
Deformational Features In The Chattanooga Shale, Near Chattanooga, Tennessee, Dewayne Adarial Ponds
Honors Theses
Several exposures of deformed middle Paleozoic rocks in the westernmost Valley and Ridge Physiographic Province, near Chattanooga, TN, reveal a variety of structures. These include centimeter-scale ellipsoidal to lensshaped masses of sandstone in the Mississippian to Devonian Chattanooga Shale. Fissility in the carbonaceous shale is intensified adjacent to these lenses and conforms to their biconvex shapes. Slickensides on rinds of highly polished shale trend northwest. The walnut- to fist-size masses are composed of fine- to medium-grained ferruginous quartz sandstone. Thin-section study reveals that the quartz grains retain detrital characteristics, but that many are broken and displaced; cataclastic deformation is particularly …
The Role Of Groundwater And Surface Water Interaction In The Development Of A 1,4-Dioxane Plume In Scio Township, Washtenaw County, Michigan, James W. Brode
The Role Of Groundwater And Surface Water Interaction In The Development Of A 1,4-Dioxane Plume In Scio Township, Washtenaw County, Michigan, James W. Brode
Masters Theses
The purpose of this study was to examine the hypothesis that groundwater and surface water interaction resulted in the development a 1,4-dioxane plume in a glacial aquifer in Scio Township, Washtenaw County, Michigan.
An industrial solvent, 1,4-dioxane, was detected in the groundwater in the area of study in 1986. This area, referred to in this investigation as the Western Plume, is one of several 1,4-dioxane plumes associated with the Pall/Gelman Sciences Inc. (P/GSI) site, an extensively investigated site of groundwater contamination.
1,4-Dioxane in the Western Plume area was initially believed to be the result of contaminated groundwater transported from a …
Multiple Isotopic Investigation Of Lake Sediments From Northern India, Alice Mwanda
Multiple Isotopic Investigation Of Lake Sediments From Northern India, Alice Mwanda
Masters Theses
Stable isotopes ratio of lake sediments can provide valuable environmental information. This possibility has been investigated using radiocarbon dated fossil lake sediments from the Himalayan region of Northern India. The chronology was established using Radiocarbon dating of both organic and inorganic fractions using (AMS). Inorganic ages are older than organic ages. Organic ages are expected to increase stratigraphically, however several anomalous old ages are found in the younger part of the sediments. Final chronology, determined using selected sensible ages identified two periods of sedimentation. The high sedimentation period is characterized by sedimentation rate of 0.8cm/yr and it fairly coincides with …
Rock Glacier Surface Motion In Beacon Valley, Antarctica, From Synthetic-Aperture Radar Interferometry, Andrew G. Fountain, Eric Rignot, Bernard Hallet
Rock Glacier Surface Motion In Beacon Valley, Antarctica, From Synthetic-Aperture Radar Interferometry, Andrew G. Fountain, Eric Rignot, Bernard Hallet
Geology Faculty Publications and Presentations
We present radar interferograms of rock glaciers in the Beacon Valley sector of the McMurdo Dry Valleys, in East Antarctica, as part of a comprehensive study of surface processes in the area. Due to the relative absence of net precipitation (snow) in this region and the stability of the surface, the rock glaciers maintain excellent coherence of the radar returns over several years. As a result, we obtain a spatially continuous surface velocity field with a precision of fractions of a millimeter per year. On distinct rock glaciers entering Beacon Valley, we find coherent velocity patterns, with peak velocities approaching …
Thermochronological Evolution Of Calcite Formation At The Potential Yucca Mountain Repository Site, Nevada: Part 2 Fluid Inclusion Analyses And Upb Dating, Jean S. Cline, Amy J. Smiecinski, Robert Bodnar
Thermochronological Evolution Of Calcite Formation At The Potential Yucca Mountain Repository Site, Nevada: Part 2 Fluid Inclusion Analyses And Upb Dating, Jean S. Cline, Amy J. Smiecinski, Robert Bodnar
Publications (YM)
The presence of two-phase fluid inclusions in thin secondary mineral crusts at the potential Yucca Mountain nuclear waste repository has raised questions regarding the origin, timing, and temperature of past fluid flow through the repository horizon. The geologically recent passage of fluids with high temperatures would call into question the suitability of the site for the storage of high level nuclear waste. This study determined the thermal history of fluid flow through the site using fluid inclusion analyses and constrained the timing of thermal fluids by dating silica minerals spatially associated with the fluid inclusions using U-Pb techniques. Results provide …
Transport Of The Herbicide Atrazine On Suspended Sediments During A Spring Storm Event In Mammoth Cave, Kentucky, Michael Anderson
Transport Of The Herbicide Atrazine On Suspended Sediments During A Spring Storm Event In Mammoth Cave, Kentucky, Michael Anderson
Masters Theses & Specialist Projects
This study examines the transport of atrazine, an herbicide used in Kentucky to control grassy and broad-leaf weeds in corn fields, on suspended sediments. Atrazine is a known carcinogen and endocrine disruptor and has been shown to be toxic at low environmental concentrations. Atrazine has the capacity to adsorb to soil particles, which in karst areas such as those found in south central Kentucky can be transported directly into the groundwater. Suspended sediments and water were collected from a well at the Hawkins River in Mammoth Cave National Park during a spring storm and tested for atrazine. Atrazine was found …
Gpr Monitoring Of Volumetric Water Content In Soils Applied To Highway Construction And Maintenance, Katherine R. Grote, Susan Sharpless Hubbard, Yoram N. Rubin
Gpr Monitoring Of Volumetric Water Content In Soils Applied To Highway Construction And Maintenance, Katherine R. Grote, Susan Sharpless Hubbard, Yoram N. Rubin
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
An overview is given on two experiments, a controlled pit study and a transportation application in subasphalt soils. Both experiments show that common-offset ground-penetrating radar (GPR) reflection data can be used to estimate θv to a high degree of accuracy. The methodology developed in these two experiments provides a technique for obtaining quick, noninvasive, accurate, and high-resolution estimates of θv.
Temporal Variation Of Seismic B-Values Beneath Northeastern Japan Island Arc, Aimin Cao, Stephen S. Gao
Temporal Variation Of Seismic B-Values Beneath Northeastern Japan Island Arc, Aimin Cao, Stephen S. Gao
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Analysis of a high quality seismic catalog reveals that the average of seismic b-values in the crust beneath most part of northeastern Japan island arc decreased from 0.86 between 1984 and 1990, to 0.73 between 1991 and 1995. The two areas with the largest decrease are found to be in the same areas where the coupling between the North American and the Pacific plates is the highest, as suggested by a recent geodetic study. In the same time period, the annual seismic moment release increased by 10 times. In addition, there seems to be a corresponding increase in volcanic activities …
Mantle Discontinuities Beneath Southern Africa, Stephen S. Gao, Paul G. Silver, Kelly H. Liu, Kaapvaal Seismic Group
Mantle Discontinuities Beneath Southern Africa, Stephen S. Gao, Paul G. Silver, Kelly H. Liu, Kaapvaal Seismic Group
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Seismic velocity discontinuities within the top 1000 km of the Earth beneath southern Africa are imaged by stacking about 1300 source-normalized broadband seismograms recorded by the Southern African Seismic Experiment. The Moho, 410, and 660 kilometer discontinuities are clearly detected. The mean mantle transition zone thickness is 245 km, essentially the same as the global average, suggesting that the transition zone is not anomalously warm. Thus, the lower-mantle 'African Superplume' beneath our study area has no discernible effect on transition zone temperature and is consequently confined to the lower mantle. Variations in transition zone thickness appear to be related to …
Physical And Chemical Heterogeneity In The Subsurface: Spatial Distribution Of Transport Parameters And Their Relation To Depositional Processes, Dana Divine
Conservation and Survey Division: Faculty and Staff Publications
This thesis consists of two parts. The goal of first section is to better understand the influence of heterogeneity on contaminant transport. This objective is approached by quantifying the heterogeneity that may have affected transport of the Stanford-Waterloo tetrachloroethene (PCE) plume. Specifically, I determine the statistical distribution of the PCE sorption distribution coefficient (Kd) at Canadian Forces Base Borden, identify the spatial distribution of Kd, and determine the cross-correlation structure between PCE Kd and permeability (k). The results show that Kd is not lognormally distributed, and that variance is insufficient to …
Sedimentology, Facies Architecture, And Reservoir Characterization Of Lacustrine Rocks, Eocene Green River And Colton Formations, Uinta Basin, Utah, Andrew W. Taylor
Sedimentology, Facies Architecture, And Reservoir Characterization Of Lacustrine Rocks, Eocene Green River And Colton Formations, Uinta Basin, Utah, Andrew W. Taylor
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Outcrop and petrographic studies of the Eocene Green River and Colton formations in the Uinta basin, Utah, document the facies architecture and heterogeneity characteristic of lacustrine reservoirs. A southwest-northeast transect of Eocene strata in the Uinta basin records three main marginal lacustrine depositional environments: fluvial, deltaic, and wave-dominated. Heterogeneity exists between and within individual depositional systems.
Reservoir rocks of Outcrops One and Two (the flu vial facies of the Colton Formation and the deltaic facies of the Green River Formation, respectively) consist of 2 to 18 m thick lenticular, tabular, or undulatory channel-fill, distributary channel, and distributary mouth bar deposits …
Evolution Of A Miocene-Pliocene Low-Angle Normal-Fault System In The Southern Bannock Range, Southeast Idaho, Stephanie M. Carney
Evolution Of A Miocene-Pliocene Low-Angle Normal-Fault System In The Southern Bannock Range, Southeast Idaho, Stephanie M. Carney
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Geologic mapping, basin analysis, and tephrochronologic analysis in the Clifton quadrangle of southeast Idaho indicates that the modern Basin-and-Range topography is only a few million years old and that the bulk of Cenozoic extension was accommodated by slip on an older low-angle normal-fault system, the Bannock detachment system. The detachment system was active between ~12 and < 4 Ma and accommodated ~50 % extension.
Cross-cutting relationships show that the master detachment fault, the Clifton fault, is the youngest low-angle normal fault of the system, was active at a low angle, and has not been rotated to a low-dip angle through time. Map patterns and relationships indicate that the …
Geometry And Physical Properties Of The Chelungpu Fault, Taiwan, And Their Effect On Fault Rupture, Richard V. Heermance
Geometry And Physical Properties Of The Chelungpu Fault, Taiwan, And Their Effect On Fault Rupture, Richard V. Heermance
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Rupture of the Chelungpu fault during the September 21, 1999, 7.6 Mwearthquake in Taiwan caused a 90-Jr,m-long surface rupture with variable displacement along strike. Analysis of core from two holes drilled through the fault zone, combined with geologic mapping and detailed investigation from three outcrops, define the fault geometry and physical properties of the Chelungpu fault in its northern and southern regions. In the northern region, the fault dips 45-60° east parallel to bedding and consists of a narrow (1-20 cm) core of dark-gray, sheared clay gouge at the base of a 30-50 m zone of increased fracture …
Relationships Between Tributary Catchments, Valley-Bottom Width, Debris-Fan Area, And Mainstem Gradient On The Colorado Plateau: A Case Study In Desolation And Gray Canyons On The Green River, Caroline M. Elliott
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The alluvial forms of the rivers that drain the Colorado Plateau are a product of the water and sediment load that tributaries deliver to the trunk streams. Where the Green and Colorado Rivers cross structural barriers, narrow canyons have been incised. In the steep terrain adjacent to many of these canyons debris flows occur in the catchment basins of tributaries and deliver coarse sediment to the mainstem river corridor. Over time, debris flow deposits have aggraded in trunk stream valleys and created landforms known as debris fans. The sizes of these debris fans are related to the accommodation space available …
The Stratigraphic, Sedimentologic, And Paleogeographic Evolution Of The Eocene- Oligocene Grasshopper Extensional Basin, Southwest Montana, Joseph P. Matoush
The Stratigraphic, Sedimentologic, And Paleogeographic Evolution Of The Eocene- Oligocene Grasshopper Extensional Basin, Southwest Montana, Joseph P. Matoush
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Grasshopper basin, located in southwest Montana, is an east-tilted graben bounded by the listric Muddy-Grasshopper fault and the Meriwether Lewis fault on the eastern and western margins of the basin, respectively. This basin contains a complex stratigraphy of intertonguing facies comprised of five unconformity-bounded sequences of Tertiary alluvial, flu vial, deltaic, and lacustrine sedimentary and volcanic rocks. Sequence 1 consists of the Challis volcanic Group (Middle Eocene). The sedimentary rocks of the Medicine Lodge beds (Late Eocene-Late Oligocene) represent sequence 2 and approximately 90% of the basin-fill within Grasshopper basin. Sequence 3 consists 11 of the Sedimentary Rocks of Everson …
Structural And Kinematic Evolution Of Eocene-Oligocene Grasshopper Extensional Basin, Southwest Montana, Julie C. Kickham
Structural And Kinematic Evolution Of Eocene-Oligocene Grasshopper Extensional Basin, Southwest Montana, Julie C. Kickham
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The Grasshopper basin of southwest Montana is a complex east-dipping graben containing five unconformity-bounded sequences of Tertiary sedimentary rocks. The Eocene-Oligocene basin lies within the northern Rocky Mountain Basin and Range province. Geologic mapping in five and a half 7.5 minute quadrangles indicates that at least three distinct phases of extension characterize the Cenozoic tectonic evolution of Grasshopper basin from approximately 46 Ma to < Ma.
The significant phases of extension in Grasshopper basin were phases 1 and 3. During the first phase of extension (46-27 Ma) the nonplanar Muddy-Grasshopper fault was initiated and 90% of the basin fill was deposited. At …
Stratigraphy And Paleoecology Of The Morrison Formation, Como Bluff, Wyoming, Melissa V. Connely
Stratigraphy And Paleoecology Of The Morrison Formation, Como Bluff, Wyoming, Melissa V. Connely
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The Morrison Formation at Como Bluff, Wyoming, has been historically known for containing a rich source of Late Jurassic vertebrate fossils. However, when collected, most of these fossils were not positioned into a stratigraphic or sedimentologic framework. Research shows that the Morrison Formation at Como Bluff can be divided into three members. These members can be identified by lithologic and paleontological characteristics. The lower Morrison members include the Windy Hill Member and the recently described Lake Como Member. The Windy Hill Member primarily contains near-shore marine sandstone. Megavertebrate fauna is lacking. The Lake Como Member contains illitic clay in red …
Geology Of The Cuesta Ridge Ophiolite Remnant Near San Luis Obispo, California: Evidence For The Tectonic Setting And Origin Of The Coast Range Ophiolite, Cameron A. Snow
Geology Of The Cuesta Ridge Ophiolite Remnant Near San Luis Obispo, California: Evidence For The Tectonic Setting And Origin Of The Coast Range Ophiolite, Cameron A. Snow
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The Cuesta Ridge ophiolite is one of the best-preserved remnants of mid-Jurassic ophiolite in California. Geologic mapping and petrologic studies show that it comprises (1) harzburgite mantle tectonite, (2) dunite-rich mantle transition zone (MTZ), (3) wehrlite and pyroxenite, (4) isotropic gabbro, (5) sheeted dike/sill complex, (6) volcanic rocks (7) late-stage dikes and flows, and (8) tuffaceous radiolarian chert.
The sheeted dike/sill complex is dominated by quartz diorite, with significant modal quartz and hornblende. The volcanic section is dominated by arc tholeiite and boninitic lavas. Boninites, with high MgO, Cr, and Ni comprise 40% of the volcanic rocks. Latestage dikes and …
Determining Flow Type In A Carbonate Bedrock Aquifer, Presque Isle County, Michigan, Bonny Armstrong
Determining Flow Type In A Carbonate Bedrock Aquifer, Presque Isle County, Michigan, Bonny Armstrong
Masters Theses
Presque Isle County, Michigan, has a long history of ground water quality problems. Aquifer contamination is most likely the result of large fractures in the bedrock allowing surface water to rapidly reach ground water. The purpose of the study is to l) perform a geochemical investigation of ground water in the bedrock aquifer, 2) suggest the type of ground water flow system present in the study area and characterize the aquifer type, and 3) suggest how the flow system might affect the behavior and transport of contaminants.
Water samples were collected from sixteen wells in the Genshaw Formation, three wells …
Stratigraphic Analysis Of Diamicton Units In Southern Allegan County, Michigan, Shannon A. Wong
Stratigraphic Analysis Of Diamicton Units In Southern Allegan County, Michigan, Shannon A. Wong
Masters Theses
Two diamicton units from the southern Allegan County, Michigan lakeshore bluffs were identified and differentiated through clay mineralogy by analysis of 7 /10A peak-height ratios and the 2-80 mm crystalline fraction from pebble count results. t-Tests indicate the two units are significantly different. These two units are correlated with the Saugatuck and the Ganges tills of southwest Michigan based on similarities in stratigraphic position and lithologic description as described by Monaghan et al. (1986). Other diamicton samples were collected throughout southwest Michigan, near Moline, Otsego, Bloomingdale, Gobles, and Decatur. In correlating the Saugatuck and the Ganges tills to their inland …
A Late Pleistocene And Holocene High-Resolution Glacial And Paleoclimate Record From The Southern Sangre De Cristo Mountains, Northern New Mexico, Jake Armour
Earth and Planetary Sciences ETDs
Bog deposits in the Winsor Creek drainage basin, southern Sangre de Cristo Mountains, New Mexico contain a high-resolution record of Pleistocene to Holocene glacial activity. Sediment cores were recovered from an alpine bog (elevation 3,100 m) behind a Pinedale age moraine, 2 km from a high-elevation (-3600 m) cirque. Three cores reached glacial talus and consist of -6 meters of finely laminated to coarsely laminated lake clays, grading into gyttja. Superimposed on this long-term, lake-bog transition record are many distinct coarse-grained detrital packages punctuating times of rapid environmental change.
Accelerator mass spectrometry (AMS) carbon dating, sedimentology, variations in rock magnetic …
Longshore Sand Transport – Initial Results From The Large-Scale Sediment Transport Facility, Ping Wang, Bruce A. Ebersole, Ernest R. Smith
Longshore Sand Transport – Initial Results From The Large-Scale Sediment Transport Facility, Ping Wang, Bruce A. Ebersole, Ernest R. Smith
Geology Faculty Publications
Accurate predictions of the total rate of longshore sand transport (LST) and its cross-shore distribution pattern in the surf zone are central to many coastal engineering studies. Present understanding and methods for calculating the LST rate are largely developed based on field studies (e.g., Komar and Inman 1970; Inman et al. 1981; Kraus et al. 1982; Bodge and Dean 1987a, b; Dean 1989; Schoonees and Theron 1993; Miller 1998; Wang, Kraus, and Davis 1998; Wang 1998; Wang and Kraus 1999; Miller 1999). The Coastal Engineering Research Center (CERC) formula (Shore Protection Manual 1984), which is based on field measurements, is …
Transition From Contraction To Extension In The Northeastern Basin And Range: New Evidence From The Copper Mountains, Nevada, Jeffrey M. Rahl, Allen J. Mcgrew, Kenneth A. Foland
Transition From Contraction To Extension In The Northeastern Basin And Range: New Evidence From The Copper Mountains, Nevada, Jeffrey M. Rahl, Allen J. Mcgrew, Kenneth A. Foland
Department of Earth, Environment and Sustainability Faculty Publications
New mapping, structural analysis, and 40Ar/39Ar dating reveal an unusually well‐constrained history of Late Eocene extension in the Copper Mountains of the northern Basin and Range province. In this area, the northeast‐trending Copper Creek normal fault juxtaposes a distinctive sequence of metacarbonate and granitoid rocks against a footwall of Upper Precambrian to Lower Cambrian quartzite and phyllite. Correlation of the hanging wall with footwall rocks to the northwest provides an approximate piercing point that requires 8–12 km displacement in an ESE direction. This displaced fault slice is itself bounded above by another normal fault (the Meadow Fork Fault), which brings …
Sedimentology And Paleoenvironments Of The Miocene/Pliocene Pisco Fm., Perú, Cristian R. Carvajal
Sedimentology And Paleoenvironments Of The Miocene/Pliocene Pisco Fm., Perú, Cristian R. Carvajal
Loma Linda University Electronic Theses, Dissertations & Projects
The main objective of this research was to understand the sedimentology and depositional environment of the diatomaceous Miocene/Pliocene Pisco Formation in the Ica Valley, Perú. Four stratigraphic sections were studied, sampled and correlated. Field data were integrated with XRD, diatom taxonomy and taphonomy, and thin section analyses to define six facies.
Facies A is composed of diatomaceous siltstone with scour and fill structures formed on a shallow shelf. Facies B was deposited on the transitional zone between the shallow shelf and nearshore where tuffaceous-diatomaceous siltstone and sandstone accumulated. In facies B, lenticular laminations, and flaser, wavy and lenticular bedding record …
Detection Of Iapetan Rifting (Rome Trough Tectonism) By Quaternary Karstification: Pulaski County, Kentucky, Lee J. Florea
Detection Of Iapetan Rifting (Rome Trough Tectonism) By Quaternary Karstification: Pulaski County, Kentucky, Lee J. Florea
Earth, Environmental, and Atmospheric Sciences Faculty Publications
No abstract provided.
Precursory Transient Slip During The 2001 MW = 8.4 Peru Earthquake Sequence From Continuous Gps, Timothy I. Melbourne, Frank H. Webb
Precursory Transient Slip During The 2001 MW = 8.4 Peru Earthquake Sequence From Continuous Gps, Timothy I. Melbourne, Frank H. Webb
Faculty Scholarship for the Cascadia Hazards Institute
Two-hour position estimates from a continuous GPS station located at Arequipa, Peru, document precursory deformation beginning 18 hours prior to an Mw = 7.6 aftershock of the June 23rd 2001 Mw = 8.4 earthquake. This preseismic signal appears on the north and east components as a slow displacement with an amplitude twice that of the subsequent coseismic. Analysis of three years of 18-hour rate measurement shows this signal to be unprecedented and beyond four standard deviations from the mean rate. The best fitting centroid is directionally consistent with slow slip along the plate interface and suggests the preseismic …