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Articles 631 - 660 of 1162

Full-Text Articles in Geophysics and Seismology

Prevailing Weather Conditions During Summer Seasons Around Gangotri Glacier, Pratap Singh, Umesh K. Haritashya, K. S. Ramasastri, Naresh Kumar Mar 2005

Prevailing Weather Conditions During Summer Seasons Around Gangotri Glacier, Pratap Singh, Umesh K. Haritashya, K. S. Ramasastri, Naresh Kumar

Department of Earth, Environment and Sustainability Faculty Publications

Meteorological data collected near the snout of the Gangotri Glacier suggest that the study area receives less rainfall. The average seasonal rainfall is observed to be about 260 mm. The rainfall distribution does not show any monsoon impact. Amount of seasonal rainfall is highly variable (131.4-368.8 mm) from year to year, but, in general, August had the maximum rainfall. A verage daily maximum and minimum temperatures were 14.7 and 4.1°C respectively, whereas average mean temperature was 9.4°C. July was recorded as the warmest month. During daytime, wind speed was four times higher than that at night-time. The average daytime and …

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Evidence For Static Stress Changes Triggering The 1999 Eruption Of Cerro Negro Volcano, Nicaragua And Regional Aftershock Sequences, M. Diez, P. C. La Femina, Charles B. Connor, W. Strauch, Tenorio V. Tenorio Feb 2005

Evidence For Static Stress Changes Triggering The 1999 Eruption Of Cerro Negro Volcano, Nicaragua And Regional Aftershock Sequences, M. Diez, P. C. La Femina, Charles B. Connor, W. Strauch, Tenorio V. Tenorio

Geology Faculty Publications

Remarkable evidence of coupling between tectonic and magmatic events emerges from investigation of three tectonic earthquakes, aftershock sequences and eruption of Cerro Negro volcano, Nicaragua in 1999. Here, we explain this coupling through static stress changes following three Mw 5.2 earthquakes. We use focal mechanism solutions to estimate fault system geometry and magnitude of slip from these events, which are then used to calculate the change in minimum horizontal principal stress (σ3) for the region and the change in Coulomb failure stress on optimally oriented fault planes. Results of these simulations indicate that σ3 was reduced by …

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Transient Detection And Modeling Of Continuous Geodetic Data, Walter Michael Szeliga Jan 2005

Transient Detection And Modeling Of Continuous Geodetic Data, Walter Michael Szeliga

All Master's Theses

Transient surface deformation has been observed by continuously operating Global Positioning System stations in the Puget Sound area during the past decade. This surface deformation is associated with processes occurring on or near the subducting plate boundary between the Juan de Fuca and North American plates. This thesis is composed of two studies of transient deformation along the Cascadia plate margin and a discussion of the methodologies employed in these studies. We model one 7-week episode of transient deformation that occurred during 2003 beneath the Puget Sound area. Additionally, we utilize a combination of continuous Global Positioning System and seismic …

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Modeling Long-Term Volcanic Hazards Through Bayesian Inference: An Example From The Tohoku Volcanic Arc, Japan, Andrew J. Martin, Koji Umeda, Charles B. Connor, Jennifer N. Weller, Dapeng Zhao, Masaki Takahashi Oct 2004

Modeling Long-Term Volcanic Hazards Through Bayesian Inference: An Example From The Tohoku Volcanic Arc, Japan, Andrew J. Martin, Koji Umeda, Charles B. Connor, Jennifer N. Weller, Dapeng Zhao, Masaki Takahashi

Geology Faculty Publications

The need to quantitatively estimate future locations of volcanoes in the long-term is of increasing importance, partly as a result of the requirement of constructing certain types of installations in regions of low geologic risk. The complex geological factors and natural processes controlling the locations of volcanoes make it problematic to estimate future patterns deterministically. Instead, the probabilistic approach can be developed with quite high levels of confidence; however, for regions with few or no volcanoes, there is a need to include additional geological and geophysical data that may indicate the likelihood of future volcanism. We achieve this using Bayesian …

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Geogram 2004, David J. Keeling Editor, Wku Department Of Geography And Geology Oct 2004

Geogram 2004, David J. Keeling Editor, Wku Department Of Geography And Geology

Earth, Environmental, and Atmospheric Sciences Publications

No abstract provided.

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Lithium Abundance And Isotope Systematics Of Forearc Serpentinites, Conical Seamount, Mariana Forearc: Insights Into The Mechanics Of Slab-Mantle Exchange During Subduction, Laurie D. Benton, Jeffrey G. Ryan, Ivan P. Savov Aug 2004

Lithium Abundance And Isotope Systematics Of Forearc Serpentinites, Conical Seamount, Mariana Forearc: Insights Into The Mechanics Of Slab-Mantle Exchange During Subduction, Laurie D. Benton, Jeffrey G. Ryan, Ivan P. Savov

Geology Faculty Publications

[1] Variable lithium contents and contrasting Li isotopic signatures are evident in the serpentininite muds and clasts extruded at Conical Seamount in the Mariana forearc. The muds have high Li contents compared to mantle values (3–7 ppm) and a mean δ7Li value of ∼+6‰. The clasts are generally lower in Li, and δ7Li varies from −6‰ to +10‰, with higher δ7Li correlating broadly to higher lithium contents. The diverse δ7Li in the serpentinite clasts suggests Li exchanges between mantle rocks and evolving slab‐derived fluids from different depths, producing a subarc mantle that is zoned in terms of Li abundances and …

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Drift Scale Test: Analyze And Report, George Danko, Davood Bahrami, Amy J. Smiecinski Mar 2004

Drift Scale Test: Analyze And Report, George Danko, Davood Bahrami, Amy J. Smiecinski

Publications (YM)

This report summarizes the results of the in situ thermophysical properties measurements as part of the Drift Scale Test (DST) measurement program at Yucca Mountain, Nevada. Thermophysical measurements have been performed with three built-in thermal probes since November 13, 1997 and were expected to continue for three more years until the end of the DST cooling period. The Department of Energy (DOE), under Cooperative Agreement, Number DEFC28- 98NV12081, has funded a research project at the University of Nevada, Reno since November, 1999 titled: "Continuing site characterization and performance verification applications with the REKA method at Yucca Mountain, Task 13." This …

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Experimental Determination Of Stiffness Of Joints In Welded Tuff, Jaak J.K. Daemen, George Danko, Amy J. Smiecinski Jan 2004

Experimental Determination Of Stiffness Of Joints In Welded Tuff, Jaak J.K. Daemen, George Danko, Amy J. Smiecinski

Publications (YM)

Fourteen uniaxial joint compression tests were run to determine the normal and shear stiffnesses of type 1 fracture joints (healed joints filled with vapor-phase mineral deposits) obtained from the Yucca Mountain site. The uniaxial joint compression results show that these joints behave linearly up to over 85% of their loading history. They are stiff with strengths very close to the strength of the intact rock. Five direct shear tests were run on open, separated, joints. Results obtained from the direct shear testing show that the normal stiffness increases with increasing normal stress. Shearing through asperities gives high joint shear stiffness …

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Structural Analysis Of The Gonic Formation In Berwick, Maine, Joseph F. Renda Jan 2004

Structural Analysis Of The Gonic Formation In Berwick, Maine, Joseph F. Renda

Geology Theses and Dissertations

RELATIONSHIP OF THE GONIC FORMATION AND NONSUCH RIVER FAULT TO THE NORUMBEGA FAULT ZONE IN BERWICK, MAINE
Located in southwestern Maine the Gonic Formation abuts the Nonesuch River Fault of the Norumbega Fault System. The rock types of the Gonic Fm. consist
predominantly of micaceous schist and lesser amounts of quartzite. Fieldwork suggests that the units have undergone transposition and thus appear to be
interlayered and pinch-out along strike. Granitoid rocks have also been observed and are interpreted as related to either the Lyman Pluton or White Mountain
Complex and serve as the backbone to the line of low-lying hills …

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Magnetic Susceptibility For The Paleocene-Eocene Boundary: Correlation Among Three Egyptian Sections, Kelli Willson Jan 2004

Magnetic Susceptibility For The Paleocene-Eocene Boundary: Correlation Among Three Egyptian Sections, Kelli Willson

Honors Capstones

No abstract provided.

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Geogram 2003, David J. Keeling Editor, Wku Department Of Geography And Geology Oct 2003

Geogram 2003, David J. Keeling Editor, Wku Department Of Geography And Geology

Earth, Environmental, and Atmospheric Sciences Publications

No abstract provided.

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Longbase Laser Strainmeter Measurements From The South Ramp Of The Yucca Mountain Facility, Frank K. Wyatt, Duncan C. Agnew, James N. Brune, Amy J. Smiecinski Oct 2003

Longbase Laser Strainmeter Measurements From The South Ramp Of The Yucca Mountain Facility, Frank K. Wyatt, Duncan C. Agnew, James N. Brune, Amy J. Smiecinski

Publications (YM)

Under subcontract (DOE/UCCSN DE-FC28-98NV12081, Task 7) from the Seismological Laboratory of the University of Nevada-Reno, the University of California, San Diego (UCSD), has designed, installed, and operated a laser strainmeter (LSM) in the Exploratory Studies Facility (ESF) at Yucca Mountain, Nevada. This instrument provides precise deformation monitoring of the (proposed) repository block. This document describes the history of the installation, outlines the principles of operation of the system, documents the integral recording and control system and file formats used, and provides information on how QA has been implemented, with the aim of being a self-contained description which could be used …

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Exploring Links Between Physical And Probabilistic Models Of Volcanic Eruptions: The Soufriere Hills Volcano, Montserrat, Charles B. Connor, R. S. J. Sparks, R. M. Mason, Costanza Bonadonna, S. R. Young Jul 2003

Exploring Links Between Physical And Probabilistic Models Of Volcanic Eruptions: The Soufriere Hills Volcano, Montserrat, Charles B. Connor, R. S. J. Sparks, R. M. Mason, Costanza Bonadonna, S. R. Young

Geology Faculty Publications

Probabilistic methods play an increasingly important role in volcanic hazards forecasts. Here we show that a probability distribution characterized by competing processes provides an excellent statistical fit (>99% confidence) to repose intervals between 75 vulcanian explosions of Soufrière Hills Volcano, Montserrat in September–October, 1997. The excellent fit is explained by a physical model in which there are competing processes operating in the upper volcano conduit on different time scales: pressurization due to rheological stiffening and gas exsolution, and depressurization due to development of permeability and gas escape. Our experience with the Soufrière Hills Volcano eruption sequence suggests that volcanic …

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Melting Processes And Fluid And Sediment Transport Rates Along The Alaska-Aleutian Arc From An Integrated U-Th-Ra-Be Isotope Study, Rhiannon George, Simon Turner, Chris Hawkesworth, Julie Morris, Chris Nye, Jeffrey G. Ryan, Shu-Hui Zheng May 2003

Melting Processes And Fluid And Sediment Transport Rates Along The Alaska-Aleutian Arc From An Integrated U-Th-Ra-Be Isotope Study, Rhiannon George, Simon Turner, Chris Hawkesworth, Julie Morris, Chris Nye, Jeffrey G. Ryan, Shu-Hui Zheng

Geology Faculty Publications

A comprehensive data set for young lavas erupted along the Alaska-Aleutian arc is used to examine how fluid and sediment transport rates and melting processes vary in response to systematic changes in subduction rate and dip along the arc and across the ocean-continent boundary. Positive correlations between convergence rate, volcano volume, and 238U excesses suggest that magmatic output is closely linked to the size of the fluid flux which occurred <10 kyr prior to eruption. Sediment-sensitive tracers like Th/Nb, Ce/Ce*, and 10Be/9Be also increase with convergence rate. However, the inferred 10Be/9Be ratio of this component is low relative to that in the incoming sediments, …

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Whole Mantle Shear Structure Beneath The East Pacific Rise, Timothy I. Melbourne, Donald V. Helmberger Sep 2002

Whole Mantle Shear Structure Beneath The East Pacific Rise, Timothy I. Melbourne, Donald V. Helmberger

All Faculty Scholarship for the College of the Sciences

We model broadband seismograms containing triplicated S, S2, and S3 along with ScS to produce a pure path one‐dimensional model extending from the crust to the core‐mantle boundary beneath the East Pacific Rise. We simultaneously model all body wave shapes and amplitudes, thereby eliminating depth‐velocity ambiguities. The data consist of western North American broadband recordings of East Pacific Rise (EPR) affiliate transform events that form a continuous record section out to 82° and sample nearly the entire East Pacific Rise. The best fitting synthetics contain attenuation and small changes in lithospheric thickness needed to correct for …

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Late Quaternary Slip Rates Across The Central Tien Shan, Kyrgyzstan, Central Asia, Stephen C. Thompson, Ray J. Weldon, Charles M. Rubin, Kanatbek Abdrakhmatov, Peter Molnar, Glenn W. Berger Sep 2002

Late Quaternary Slip Rates Across The Central Tien Shan, Kyrgyzstan, Central Asia, Stephen C. Thompson, Ray J. Weldon, Charles M. Rubin, Kanatbek Abdrakhmatov, Peter Molnar, Glenn W. Berger

All Faculty Scholarship for the College of the Sciences

Slip rates across active faults and folds show that late Quaternary faulting is distributed across the central Tien Shan, not concentrated at its margins. Nearly every intermontane basin contains Neogene and Quaternary syntectonic strata deformed by Holocene north‐south shortening on thrust or reverse faults. In a region that spans two thirds of the north‐south width of the central Tien Shan, slip rates on eight faults in five basins range from ∼0.1 to ∼3 mm/yr. Fault slip rates are derived from faulted and folded river terraces and from trenches. Radiocarbon, optically stimulated luminescence, and thermoluminescence ages limit ages of terraces and …

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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 Mar 2002

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 …

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Detection Of Iapetan Rifting (Rome Trough Tectonism) By Quaternary Karstification: Pulaski County, Kentucky, Lee J. Florea Jan 2002

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.

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Stratigraphy And Diagenesis Of The Paleoproterozoic Bushy Park Zinc-Lead Deposit, South Africa, William Daniel Baugaard Jan 2002

Stratigraphy And Diagenesis Of The Paleoproterozoic Bushy Park Zinc-Lead Deposit, South Africa, William Daniel Baugaard

Masters Theses

“The Bushy Park zinc-lead deposit is located in the Northern Cape Province, South Africa. The sulfides are hosted by karst-related breccias that were formed in carbonate shelf deposits of the Neoarchean (2.55 Ga) Campbellrand Subgroup. These rocks are dolomitized completely and silicified partially but have not undergone major metamorphism and thus display remarkable preservation of depositional fabrics. The stratigraphic interval includes the Papkuil and Klippan Formations (> 210 m), a sequence of cyclic microbial laminates interbedded with domed and columnar stromatolites. The Klippan is distinguished from other formations b intense silicification and brecciation. These strata are overlain by the Kogelbeen …

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Interpreting Fracture Patterns In Sandstones Interbedded With Ductile Strata At The Salt Valley Anticline, Arches National Park, Utah, John C. Lorenz, Scott P. Cooper Nov 2001

Interpreting Fracture Patterns In Sandstones Interbedded With Ductile Strata At The Salt Valley Anticline, Arches National Park, Utah, John C. Lorenz, Scott P. Cooper

All U.S. Government Documents (Utah Regional Depository)

Sandstones that overlie or that are interbedded with evaporitic or other ductile strata commonly contain numerous localized domains of fractures, each covering an area of a few square miles. Fractures within the Entrada Sandstone at the Salt Valley Anticline are associated with salt mobility within the underlying Paradox Formation. The fracture relationships observed at Salt Valley (along with examples from Paleozoic strata at the southern edge of the Holbrook basin in northeastern Arizona, and sandstones of the Frontier Formation along the western edge of the Green River basin in southwestern Wyoming), show that although each fracture domain may contain consistently …

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Refined Kinematics Of The Eastern California Shear Zone From Gps Observations, 1993-1998, M. Meghan Miller, Timothy H. Dixon, Roy K. Dokka Feb 2001

Refined Kinematics Of The Eastern California Shear Zone From Gps Observations, 1993-1998, M. Meghan Miller, Timothy H. Dixon, Roy K. Dokka

All Faculty Scholarship for the College of the Sciences

Global Positioning System (GPS) results from networks spanning the Eastern California shear zone and adjacent Sierra Nevada block, occupied annually between 1993 and 1998, constrain plate margin kinematics. We use an elastic block model to relate GPS station velocities to long‐term fault slip rate estimates. The model accounts for elastic strain accumulation on the San Andreas fault, as well as faults of the Eastern California shear zone. South of the Garlock fault, 14 mm/yr of dextral shear is distributed across the Eastern California shear zone. Some of this slip penetrates eastward into the Basin and Range, and a collective budget …

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Constraining The Crystallization And Post-Crystallization History Of The Wallamatogus Pluton, Maine, Using Compositional Data From Garnet, Biotite And Muscovite, Joy Kathleen Drake Jan 2001

Constraining The Crystallization And Post-Crystallization History Of The Wallamatogus Pluton, Maine, Using Compositional Data From Garnet, Biotite And Muscovite, Joy Kathleen Drake

Masters Theses

"The Wallamatogus Pluton, Maine, exhibits systematic variation in grain size, mineralogy, and phenocryst abundance (alkali-feldspar) from the margin to the center of the pluton. Three facies are recognized: 1) outermost, seriate, coarse-grained (Owe), 2) porphyritic medium- to fine-grained (Dwp ), 3) innermost, fine-grained equigranular (Dwf). These facies are concentrically arranged and their contacts are gradational. Muscovite and biotite occur in all facies; the outer two facies contain garnet, and tourmaline. Muscovite and biotite grains within micaceous enclaves compositionally overlap primary muscovite, suggesting that they are early-crystallized accumulations. Muscovite in multiphase clusters and secondary muscovite compositionally overlap, suggesting formation during post-crystallization …

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Comparisons Of Gravity Anomalies At Pseudofaults, Fracture Zones, And Nontransform Discontinuities From Fast To Slow Spreading Areas, Sarah E. Kruse, Sarah F. Tebbens, David F. Naar, Qingyuan Y. Lou, Robert T. Bird Dec 2000

Comparisons Of Gravity Anomalies At Pseudofaults, Fracture Zones, And Nontransform Discontinuities From Fast To Slow Spreading Areas, Sarah E. Kruse, Sarah F. Tebbens, David F. Naar, Qingyuan Y. Lou, Robert T. Bird

Geology Faculty Publications

Published mechanisms for rift tip propagation at spreading centers include extensional deformation and an initial period of slow spreading. We investigate whether the gravity signal and inferred crustal structure at pseudofaults formed in medium to superfast spreading environments resemble the gravity signal at fracture zones or nontransform discontinuities formed in slow spreading environments. We find that altimetry-based gravity anomalies on the Mathematician, Bauer, Easter, Juan Fernandez, and northern Chile Ridge pseudofaults, located in 75–150 mm/yr (full rate) seafloor spreading environments, are similar in amplitude and form to Atlantic fracture zones with 20–30 mm/yr spreading rates. A 5–15 mGal positive mantle …

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New Kinematic Models For Pacific‐North America Motion From 3 Ma To Present, Ii: Evidence For A “Baja California Shear Zone”, Timothy Dixon, Fred Farina, Charles Demets, Francisco Suarez-Vidal, John Fletcher, Bertha Marquez-Azua, M. Meghan Miller, Osvaldo Sanchez, Paul Umhoefer Dec 2000

New Kinematic Models For Pacific‐North America Motion From 3 Ma To Present, Ii: Evidence For A “Baja California Shear Zone”, Timothy Dixon, Fred Farina, Charles Demets, Francisco Suarez-Vidal, John Fletcher, Bertha Marquez-Azua, M. Meghan Miller, Osvaldo Sanchez, Paul Umhoefer

All Faculty Scholarship for the College of the Sciences

We use new models for present‐day Pacific‐North America motion to evaluate the tectonics of offshore regions west of the Californias. Vandenburg in coastal Alta California moves at the Pacific plate velocity within uncertainties (∼1 mm/yr) after correcting for strain accumulation on the San Andreas and San Gregorio‐Hosgri faults with a model that includes a viscoelastic lower crust. Modeled and measured velocities at coastal sites in Baja California south of the Agua Blanca fault, a region that most previous models consider Pacific plate, differ by 3–8 mm/yr, with coastal sites moving slower that the Pacific plate. We interpret these discrepancies in …

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Present‐Day Motion Of The Sierra Nevada Block And Some Tectonic Implications For The Basin And Range Province, North American Cordillera, Timothy H. Dixon, M. Meghan Miller, Frederic Farina, Hongzhi Wang, Daniel Johnson Feb 2000

Present‐Day Motion Of The Sierra Nevada Block And Some Tectonic Implications For The Basin And Range Province, North American Cordillera, Timothy H. Dixon, M. Meghan Miller, Frederic Farina, Hongzhi Wang, Daniel Johnson

All Faculty Scholarship for the College of the Sciences

Global Positioning System (GPS) data from five sites on the stable interior of the Sierra Nevada block are inverted to describe its angular velocity relative to stable North America. The velocity data for the five sites fit the rigid block model with rms misfits of 0.3 mm/yr (north) and 0.8 mm/yr (east), smaller than independently estimated data uncertainty, indicating that the rigid block model is appropriate. The new Euler vector, 17.0°N, 137.3°W, rotation rate 0.28 degrees per million years, predicts that the block is translating to the northwest, nearly parallel to the plate motion direction, at 13–14 mm/yr, faster than …

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Multibeam Sonar Backscatter Lineaments And Anthropogenic Organic Components In Lacustrine Silty Clay, Evidence Of Shipping In Western Lake Ontario, C F Michael Lewis, L A. Mayer, Prasanta K. Mukhopadhyay, Michael A. Kruge, John P. Coakley, M D. Smith Jan 2000

Multibeam Sonar Backscatter Lineaments And Anthropogenic Organic Components In Lacustrine Silty Clay, Evidence Of Shipping In Western Lake Ontario, C F Michael Lewis, L A. Mayer, Prasanta K. Mukhopadhyay, Michael A. Kruge, John P. Coakley, M D. Smith

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

A multibeam sonar survey (95 kHz) covering more than 500 km2 of western Lake Ontario revealed anomalous lineaments of relatively high backscatter. The lineaments did not align with or parallel the most prominent structural zones beneath the lake as expected. Instead, the principal lineaments lay on lines between ports on opposite sides of the lake, especially between Toronto and Welland Canal, and Toronto and Niagara River mouth. As the lineaments underlie current and historical shipping routes used during the steamship era, they are interpreted as an acoustic response to shipping debris cumulated in the near-surface bottom sediment. An exploratory …

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Surficial Slip Distribution On The Central Emerson Fault During The June 28, 1992, Landers Earthquake, California, Sally F. Mcgill, Charles M. Rubin Mar 1999

Surficial Slip Distribution On The Central Emerson Fault During The June 28, 1992, Landers Earthquake, California, Sally F. Mcgill, Charles M. Rubin

All Faculty Scholarship for the College of the Sciences

We present the results of our mapping of a 5.6‐km length of the central Emerson fault that ruptured during the 1992 Landers earthquake in the southwestern Mojave Desert, California. The right‐lateral slip along this portion of the rupture varied from about 150 to 530 cm along the main rupture zone. In some locations a total of up to 110 cm of additional right‐lateral slip occurred on secondary faults up to 1.7 km away from the main rupture zone. Other secondary faults carried up to several tens of centimeters of left‐lateral or thrust displacement. The maximum net vertical displacement was 175 …

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Stability Of Paleosinks And Karstic Carbonates In The Southern Fire Clay Mining District Of Missouri, Robert Weiser Dillon Jan 1999

Stability Of Paleosinks And Karstic Carbonates In The Southern Fire Clay Mining District Of Missouri, Robert Weiser Dillon

Doctoral Dissertations

"The Southern Fire Clay District of Missouri was intensely mined during the late-1800’s to mid-1900’s for its valuable resource of high refractory clays deposited within Pennsylvanian sinkholes “paleosinks”. Mining operations have produced modifications in the Ozark aquifer, which in effect has possibly increased the instability of this paleokarst terrain and the potential of further environmental impacts to the land. Evidence supporting this hypothesis are: (1) A southerly shift in the regional groundwater divide relative to the topographic divide. This possibly is caused by the distribution of leaking clay pits, which suggests that the bedrock permeability or hydraulic conductivity has been …

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Quartzite Fabric Transition In A Cordilleran Metamorphic Core Complex, Allen J. Mcgrew, Martin Casey Jan 1998

Quartzite Fabric Transition In A Cordilleran Metamorphic Core Complex, Allen J. Mcgrew, Martin Casey

Department of Earth, Environment and Sustainability Faculty Publications

Photomicrographs 143A-143F record fabric variations in quartzite with increasing structural depth in a > 1 km thick, amphibolite-facies, normal-sense shear zone in the East Humboldt metamorphic core complex, Nevada (Figure 143.1). This shear zone and the overlying detachment system unroofed an infrastructure of high-grade, migmatitic gneiss during Oligocene to early Miocene extension (Dallmeyer and others, 1986; Wright and Snoke, 1993; McGrew and Snee, 1994). Thermobarometric constraints from near the base of the mylonitic zone record deformation conditions of 550°- 620°C and 300-400 MPa (Hurlow and others, 1991). Sample WBC6 (l43A and 143B) characterizes the mylonitic zone, whereas sample 8706-1 (143C and …

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Effective Elastic Thickness Of The Lithosphere Along The Easter Seamount Chain, Sarah E. Kruse, Zhengro J. Liu, David F. Naar, Robert A. Duncan Dec 1997

Effective Elastic Thickness Of The Lithosphere Along The Easter Seamount Chain, Sarah E. Kruse, Zhengro J. Liu, David F. Naar, Robert A. Duncan

Geology Faculty Publications

Bathymetry and gravity data collected during Legs 5, 6, and 7 of the 1993 GLORIA Expedition and the recently released 2-min altimetry-derived global gravity grid are used to determine the effective elastic thickness of the lithosphere along the Easter Seamount Chain (ESC). Forward modeling, admittance, and coherence methods yield consistent results. With the exception of the eastern and western ends of the ESC the effective elastic thickness along the chain is ∼1–4 km. The thin elastic thickness for the majority of the ESC seamounts is compatible with a young seafloor age at the time of loading derived from new radiometric …

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