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Articles 151 - 173 of 173

Full-Text Articles in Physical Sciences and Mathematics

San Andreas Structural Interpretation: Merging Geophysical And Geological Data At Safod And Vicinity, Rebekah E. Wood, James P. Evans, Peter E. Malin Nov 2010

San Andreas Structural Interpretation: Merging Geophysical And Geological Data At Safod And Vicinity, Rebekah E. Wood, James P. Evans, Peter E. Malin

Rebekah Wood

No abstract provided.


Late Quaternary Distribution And Biogeography Of The Southern Lake Eyre Basin (Sleb) Megafauna, South Australia, Steve Webb Aug 2010

Late Quaternary Distribution And Biogeography Of The Southern Lake Eyre Basin (Sleb) Megafauna, South Australia, Steve Webb

Steve Webb

Understanding the population demography, species distribution and biogeography of Australia’s megafauna is essential for understanding their extinction. This process is only just beginning, and this article discusses these aspects while concentrating on a particular region; the southern Lake Eyre Basin (SLEB). It is also the first detailed description of the distribution of megafauna across that region of central Australia. The data are based on an extensive longitudinal study of 41 palaeontological sites spread across 250 000km2. Megafauna adaptation and response to extensive environmental change during the late Quaternary is reflected in the composition and distribution of 21 megafauna species found …


Cenozoic Mass Extinctions In The Deep Sea; What Disturbs The Largest Habitat On Earth?, Ellen Thomas Feb 2010

Cenozoic Mass Extinctions In The Deep Sea; What Disturbs The Largest Habitat On Earth?, Ellen Thomas

Ellen Thomas

No abstract provided.


Fabric Development In Cm-Scale Shear Zones In Ultramafic Rocks, Red Hills, New Zealand, Caroline Webber, Julie Newman, Caleb Holyoke, Timothy Little, Basil Tikoff Dec 2009

Fabric Development In Cm-Scale Shear Zones In Ultramafic Rocks, Red Hills, New Zealand, Caroline Webber, Julie Newman, Caleb Holyoke, Timothy Little, Basil Tikoff

Caleb Holyoke

No abstract provided.


Accurate Differential Stress Measurement Using The Molten Salt Cell And Solid Salt Assemblies In The Griggs Apparatus With Applications To Strength, Piezometers And Rheology, Caleb Holyoke, Andreas Kronenberg Dec 2009

Accurate Differential Stress Measurement Using The Molten Salt Cell And Solid Salt Assemblies In The Griggs Apparatus With Applications To Strength, Piezometers And Rheology, Caleb Holyoke, Andreas Kronenberg

Caleb Holyoke

No abstract provided.


Deformation Of Single Crystal Sample Using D-Dia Apparatus Coupled With Synchrotron X-Rays: In-Situ Stress And Strain Measurements At High Pressure And Temperature, Jennifer Girard, Jiuhua Chen, Paul Raterron, Caleb Holyoke Dec 2009

Deformation Of Single Crystal Sample Using D-Dia Apparatus Coupled With Synchrotron X-Rays: In-Situ Stress And Strain Measurements At High Pressure And Temperature, Jennifer Girard, Jiuhua Chen, Paul Raterron, Caleb Holyoke

Caleb Holyoke

No abstract provided.


Forward Modeling Synsedimentary Deformation Associated With A Prograding Steep-Sloped Carbonate Margin, Phillip G. Resor Dec 2009

Forward Modeling Synsedimentary Deformation Associated With A Prograding Steep-Sloped Carbonate Margin, Phillip G. Resor

Phillip G Resor

Differential compaction associated with prograding and aggrading steep-rimmed carbonate margins leads to penecontemporaneous and post- depositional modifications of stratal geometries and tensile and shear stress concentrations that result in brittle deformation. In an effort to investigate controls on these deformation processes, we employ a step-wise gravity loaded elastic model that captures pre-failure displacement and stress field patterns for a depositional geometry based on the Permian Capitan depositional system, Guadalupe Mountains, West Texas and New Mexico, USA. We consider four model geometries with varying progradation to aggradation (P/A) ratio, from strongly prograding (P/A=10) to strongly aggrading (P/A=0.1). The strongly prograding case …


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

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

Lee J Florea, PhD, P.G.

In southeastern Florida, locally delineated, small, poorly explored caves and subtle karst are characteristic of the limestone that composes the unconfined Biscayne aquifer – one of the most permeable aquifers in the world. The main units of the Biscayne aquifer are the Fort Thompson Formation and Miami Limestone, both characterized by eogenetic karst.


Late Quaternary Distribution And Biogeography Of The Southern Lake Eyre Basin (Sleb) Megafauna, South Australia, Steve Webb May 2009

Late Quaternary Distribution And Biogeography Of The Southern Lake Eyre Basin (Sleb) Megafauna, South Australia, Steve Webb

Steve Webb

Understanding the population demography, species distribution and biogeography of Australia’s megafauna is essential for understanding their extinction. This process is only just beginning, and this article discusses these aspects while concentrating on a particular region; the southern Lake Eyre Basin (SLEB). It is also the first detailed description of the distribution of megafauna across that region of central Australia. The data are based on an extensive longitudinal study of 41 palaeontological sites spread across 250 000km2. Megafauna adaptation and response to extensive environmental change during the late Quaternary is reflected in the composition and distribution of 21 megafauna species found …


Slip Heterogeneity On A Corrugated Fault, Phillip G. Resor, Vanessa E. Meer Dec 2008

Slip Heterogeneity On A Corrugated Fault, Phillip G. Resor, Vanessa E. Meer

Phillip G Resor

Slip heterogeneity reflects the fundamental physics of earthquake rupture and has been attributed to strong fault patches termed asperities or barriers. We propose that variations in fault-surface orientation due to slip-parallel corrugations may act as geometric asperities and barriers, generating variations in incremental (i.e. due to a single earthquake) slip across a fault surface. We evaluate this hypothesis using observations from the Arkitsa normal fault exposure in central Greece. A scan of the Arkitsa fault surface with 1-m spatial resolution and mm-scale precision reveals corrugations made up of 1–5 m wide synforms, antiforms, and nearly planar fault sections with long …


Plio-Quaternary Exhumation History Of The Central Nepalese Himalaya: 1. Apatite And Zircon Fission Track And Apatite [U-Th]/He Analyses, Ann Blythe, D Burbank, A Carter, K Schmidt, J Putkonen May 2007

Plio-Quaternary Exhumation History Of The Central Nepalese Himalaya: 1. Apatite And Zircon Fission Track And Apatite [U-Th]/He Analyses, Ann Blythe, D Burbank, A Carter, K Schmidt, J Putkonen

Ann Blythe

No abstract provided.


In The Heat Of The Law, It's Not Just Steam: Geothermal Resources And The Impact On Thermophile Biodiversity, Donald J. Kochan, Tiffany Grant Dec 2006

In The Heat Of The Law, It's Not Just Steam: Geothermal Resources And The Impact On Thermophile Biodiversity, Donald J. Kochan, Tiffany Grant

Donald J. Kochan

Significant research has been conducted into the utilization of geothermal resources as a ‘green’ energy source. However, minimal research has been conducted into geothermal resource utilization and depletion impacts on thermophile biodiversity. Thermophiles are organisms which have adapted over millions of year to extreme temperature and chemical compositions and exist in hot springs and other geothermal resources. Their ability to withstand high temperatures makes them invaluable to scientific and medical research. Current federal and California case law classify geothermal resources as a mineral, not a water resource. Acquisition of rights to develop a geothermal resource owned or reserved by the …


The Karst Of West-Central Florida, Lee J. Florea Aug 2006

The Karst Of West-Central Florida, Lee J. Florea

Lee J Florea, PhD, P.G.

Caves, the cornerstone feature of karst aquifers, are little understood in Florida. This dissertation, which analyzes the morphology, elevation, lithologic setting, and hydrology of caves in west-central Florida, demonstrates that the karst of the unconfined Floridan aquifer differs from the paradigm view of karst presented in modern geology textbooks. The differences reflect setting: eogenetic (west-central Florida) vs. telogenetic (conventional).


Formation And Maintenance Of Shear Zones, Caleb Holyoke, Jan Tullis Dec 2005

Formation And Maintenance Of Shear Zones, Caleb Holyoke, Jan Tullis

Caleb Holyoke

No abstract provided.


Mechanisms Of Weak Phase Interconnection And The Effects Of Phase Strength Contrast On Fabric Development, Caleb Holyoke, Jan Tullis Dec 2005

Mechanisms Of Weak Phase Interconnection And The Effects Of Phase Strength Contrast On Fabric Development, Caleb Holyoke, Jan Tullis

Caleb Holyoke

No abstract provided.


The Interaction Between Reaction And Deformation: An Experimental Study Using A Biotite + Plagioclase + Quartz Gneiss, Caleb Holyoke, Jan Tullis Dec 2005

The Interaction Between Reaction And Deformation: An Experimental Study Using A Biotite + Plagioclase + Quartz Gneiss, Caleb Holyoke, Jan Tullis

Caleb Holyoke

No abstract provided.


An Experimental Study Of Grain Scale Melt Segregation Mechanisms In Two Common Crustal Rock Types, Caleb W. Holyoke Iii, Tracy Rushmer Dec 2001

An Experimental Study Of Grain Scale Melt Segregation Mechanisms In Two Common Crustal Rock Types, Caleb W. Holyoke Iii, Tracy Rushmer

Caleb Holyoke

No abstract provided.


Karst Genetic Model For The French Bay Breccia Deposits, San Salvador, Bahamas, Lee J. Florea, John Mylroie, Jim Carew Dec 2000

Karst Genetic Model For The French Bay Breccia Deposits, San Salvador, Bahamas, Lee J. Florea, John Mylroie, Jim Carew

Lee J Florea, PhD, P.G.

No abstract provided.


Past Leaded Gasoline Emissions As A Nonpoint Source Tracer In Riparian Systems: A Study Of River Inputs To San Francisco Bay, Charles E. Dunlap, Robin Bouse, A. Russell Flegal Dec 1999

Past Leaded Gasoline Emissions As A Nonpoint Source Tracer In Riparian Systems: A Study Of River Inputs To San Francisco Bay, Charles E. Dunlap, Robin Bouse, A. Russell Flegal

Charles Dunlap

Variations in the isotopic composition of lead in 1995- 1998 river waters flowing into San Francisco Bay trace the washout of lead deposited in the drainage basin from leaded gasoline combustion. At the confluence of the Sacramento and San Joaquin rivers where they enter the Bay, the isotopic compositions of lead in the waters define a linear trend away from the measured historical compositions of leaded gas in California. The river waters are shifted away from leaded gasoline values and toward an isotopic composition similar to Sierra Nevadan inputs which became the predominant source of sedimentation in San Francisco Bay …


Regional Hydrology Of The Dixie Valley Geothermal Field, Nevada: Preliminary Interpretations Of Chemical And Isotopic Data, Gregory Nimz, Cathy Janik, Fraser Goff, Charles Dunlap, Mark Huebner, Dale Counce, Stuart Johnson Sep 1999

Regional Hydrology Of The Dixie Valley Geothermal Field, Nevada: Preliminary Interpretations Of Chemical And Isotopic Data, Gregory Nimz, Cathy Janik, Fraser Goff, Charles Dunlap, Mark Huebner, Dale Counce, Stuart Johnson

Charles Dunlap

Chemical and isotopic analyses of Dixie Valley regional waters indicate several distinct groups ranging in recharge age from Pleistocene (<20 ka) to recent (<50a). Valley groundwater is older than water from perennial springs and artesian wells in adjacent ranges, with Clan Alpine range (east) much younger (most <50a) than Stillwater range (west; most > 1OOOa).Geothermal field fluids (-12-14 ka) appear derived from water similar in composition to non-thermal groundwater observed today in valley artesian wells (also -14 ka). Geothermal fluid interaction with mafic rocks (Humboldt Lopolith) appears to be common, and significant reaction with granodiorite may also occur. Despite widespread occurrence of carbonate rocks, largescale chemical interaction appears minor. Age asymmetry of the ranges, more extensive interaction with deep- seated waters in the west, and distribution of springs and artesian wells suggest the existence …


Biogeography Of The Late Paleocene Benthic Foraminiferal Extinction, Ellen Thomas Dec 1997

Biogeography Of The Late Paleocene Benthic Foraminiferal Extinction, Ellen Thomas

Ellen Thomas

During the Late Paleocene Thermal Maximum (LPTM) benthic foraminifera at middle bathyal and greater depths suffered extinction of 30-50% of species during a few thousand years. Extinction was less severe at neritic to upper bathyal depths, where temporary changes in faunal composition prevailed. Pre-extinction deep-sea faunas were cosmopolitan and diverse, and contained heavily calcified species. Immediate post-extinction faunas were more variable geographically, exhibited low diversity, and were dominated by thin-walled calcareous or agglutinated taxa, possibly because CaCO3 dissolution increased globally from neritic to abyssal depths just before the extinction. These assemblages were dominated either by long-lived taxa such as Nuttallides …


Miocene Paleogeography Of West-Central California--Offset Along The San Gregorio-Hosgri Fault Zone, Clarence Hall Jr, Mark Sutherland, Raymond Ingersoll Dec 1994

Miocene Paleogeography Of West-Central California--Offset Along The San Gregorio-Hosgri Fault Zone, Clarence Hall Jr, Mark Sutherland, Raymond Ingersoll

Mark Sutherland

The major faults that occur in the region are described and the amount of lateral offset used to construct palinspastic maps is given. The longest, most controversial, and most critical fault relative to the palinspastic maps is the San Gregorio-San Simeon-Hosgri fault, which is discussed in detail


Subduction Of The Caribbean Plate And Basement Uplifts In The Overriding South American Plate, James N. Kellogg, William E. Bonini May 1982

Subduction Of The Caribbean Plate And Basement Uplifts In The Overriding South American Plate, James N. Kellogg, William E. Bonini

James N Kellogg

Abstract. The new tectonic interpretations presented in this paper are based on geologic field mapping and gravity data supplemented by well logs, seismic profiles, and radiometric and earthquake data. The present Caribbean-South American plate boundary is the South Caribbean marginal fault, where subduction is indicated by folding and thrusting in the deformed belt and a seismic zone that dips 30o to the southeast and terminates 200 km below the Maracaibo Basin. The Caribbean-South American convergence rate is estimated as 1.9 +_. 0.3 cm/yr on the basis of the 390-km length of the seismic zone and a thermal equilibration time of …