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Articles 1 - 21 of 21
Full-Text Articles in Geology
Multivariate Spectral Analysis Of Crism Data To Characterize The Composition Of Mawrth Vallis, Melissa Luna
Multivariate Spectral Analysis Of Crism Data To Characterize The Composition Of Mawrth Vallis, Melissa Luna
Melissa Luna
No abstract provided.
Locating Cryptotephra In Sediments Using Fluid Imaging Technology, Robert D'Anjou, Nicholas L. Balascio, Raymond S. Bradley
Locating Cryptotephra In Sediments Using Fluid Imaging Technology, Robert D'Anjou, Nicholas L. Balascio, Raymond S. Bradley
Raymond S Bradley
We report a new approach to locate and quantify cryptotephra in sedimentary archives using a continuously-imaging Flow Cytometer and Microscope (FlowCAM_). The FlowCAM rapidly photographs particles flowing in suspension past a microscope lens and performs semi-automated analysis of particle images. It has had primarily biological applications, although the potential sedimentological applications are numerous. Here we test the ability of this instrument to image irregularly shaped, vesicular glass shards and to screen sediment samples for the presence of cryptotephra. First, reference samples of basalt and rhyolite tephra (sieved <63>microns) were analyzed with the FlowCAM, demonstrating the ability of the instrument to …
Isotopes Of Carbon In A Karst Aquifer Of The Cumberland Platea Of Kentucky , Usa, Lee J. Florea
Isotopes Of Carbon In A Karst Aquifer Of The Cumberland Platea Of Kentucky , Usa, Lee J. Florea
Lee J Florea, PhD, P.G.
In this study, the concentration and isotopic composition of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) are measured in the karst groundwater of the Otter Creek watershed of the Cumberland Plateau of Kentucky, USA. Comparisons among these data and with the geochemistry of carbonate and gypsum equilibrium reactions reveal that DOC concentration is inversely related to discharge, multiple reaction pathways provide DIC with isotopic enrichment that may be directly related to mineral saturation, and oxidation of reduced sulfur is possible for dissolution. DOC is derived from C3 vegetation with an average δ13CDOC of ‒27‰. DIC in groundwater is …
Determination Of The Cec In Srs Soils And The Capability Of Epa Model 9081 For Cec Of Acidic Soils, Alexandra Simpson
Determination Of The Cec In Srs Soils And The Capability Of Epa Model 9081 For Cec Of Acidic Soils, Alexandra Simpson
Alexandra M Simpson
No abstract provided.
Determination Of The Cec In Srs Soils And The Capability Of Epa Model 9081 For Cec Of Acidic Soils, Alexandra Simpson
Determination Of The Cec In Srs Soils And The Capability Of Epa Model 9081 For Cec Of Acidic Soils, Alexandra Simpson
Alexandra M Simpson
No abstract provided.
The Effects Of Evapotranspiration Upon Recharge Using The Stable Isotopes Of Oxygen And Hydrogen In The Carbonate Aquifers Of The Cumberland Plateau In Southeast Kentucky, Lee J. Florea
Lee J Florea, PhD, P.G.
In this brief manuscript, we consider the variation of the stable isotopes of oxygen, δ18O, and hydrogen, δ2H, in samples collected during 2010 and 2011 from precipitation and shallow groundwater along the Cumberland Plateau of southeast Kentucky. These data from the 1,900-ha Redmond Creek karst aquifer lend insight into the source and timing of recharge to shallow groundwater in the epigenic karst of the U.S midcontinent. Specifically, we find that only 43% of precipitation remains as potential recharge after accounting for evapotranspiration, and 85% of this potential recharge occurs during only four two-week sampling periods. The isotopic composition of precipitation …
Thermal Fluid And Fault Interactions At The Intersection Of Two Faults, Agua Caliente, California, Rebekah Wood, James Evans
Thermal Fluid And Fault Interactions At The Intersection Of Two Faults, Agua Caliente, California, Rebekah Wood, James Evans
Rebekah Wood
Agua Caliente Springs lies at a unique intersection between the NNW-trending Elsinore fault and the 40° northeast-dipping, likely inactive West Salton detachment fault; it provides an opportunity to study damage zone geometry, fault behavior in crystalline rocks, a left-stepover, microseismicity, and the influence of thermal fluids on rock deformation. The Elsinore fault bounds the northwestern flank of the Tierra Blanca Mountains with strike-slip and normal motion; the detachment fault wraps around the northernmost portion of the mountains. Damage along the Elsinore ranges in thickness from a narrow slip plane to > 100 m along the eastern flank of the Tierra Blanca …
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 …
Presence Of A Long-Term Lithospheric Thermal Anomaly: Evidence From Apatite Fission-Track Analysis In Northern New England, Mary K. Roden-Tice, David P. West Jr., Jaime K. Potter, Sarah M. Raymond, Jenny L. Winch
Presence Of A Long-Term Lithospheric Thermal Anomaly: Evidence From Apatite Fission-Track Analysis In Northern New England, Mary K. Roden-Tice, David P. West Jr., Jaime K. Potter, Sarah M. Raymond, Jenny L. Winch
Mary K. Roden-Tice
Apatite fission-track (AFT) ages from 56 samples of Paleozoic and Mesozoic crystalline rocks in New Hampshire, northeastern Vermont, and western Maine range from 70 to 140 Ma and reflect widespread Early to Late Cretaceous cooling. The regional AFT age distributions determined in this study suggest that reactivation of preexisting orogen-parallel faults and the presence of a long-lived thermal anomaly in the lithospheric mantle controlled the late unroofing history of this part of the northern Appalachians. A northeast-trending zone of young, dominantly Late Cretaceous AFT ages (70-118 Ma) extends from southwestern New Hampshire through the central White Mountain region and continues …
A Microwave Digestion Technique For The Extraction Of Fossil Diatoms From Coastal Lake And Swamp Sediments, Jeffrey Parr, Kathryn Taffs, Christopher Lane
A Microwave Digestion Technique For The Extraction Of Fossil Diatoms From Coastal Lake And Swamp Sediments, Jeffrey Parr, Kathryn Taffs, Christopher Lane
Jeffrey Parr
This study provides an introduction to a microwave digestion technique for the extraction of fossil diatoms from sediments. The microwave technique is compared with the standard diatom extraction technique of Battarbee (Diatom analysis. In: Berglund B.E. (ed.), Handbook of Holocene Palaeoecology and Palaeohydrology. John Wiley and Sons) that uses a combination of dilute hydrochloric acid and hydrogen peroxide and the advantages and disadvantages of their use are discussed. The results suggest that the microwave technique is fast, inexpensive and most importantly produces replicable fossil diatom assemblage data. Small samples sizes are used (0.3 g) for the microwave method thus lower …
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 …
Plio-Quaternary Exhumation History Of The Central Nepalese Himalaya: 2. Thermo-Kinematic Model Of Thermochronometer Age Prediction Model, David Whipp Jr, Todd Ehlers, Ann Blythe, Katharine Huntington, Kip Hodges, Douglas Burbank
Plio-Quaternary Exhumation History Of The Central Nepalese Himalaya: 2. Thermo-Kinematic Model Of Thermochronometer Age Prediction Model, David Whipp Jr, Todd Ehlers, Ann Blythe, Katharine Huntington, Kip Hodges, Douglas Burbank
Ann Blythe
[1] In the Himalaya and other active convergent orogens, linear relationships between thermochronometer sample age and elevation are often used to estimate long-term exhumation rates. In these regions, high-relief topography and nonvertical exhumation pathways may invalidate such one-dimensional (1-D) interpretations and lead to significant errors. To quantify these errors, we integrate apatite fission track (AFT) ages from the central Himalaya with a 3-D coupled thermokinematic model, from which sample cooling ages are predicted using a cooling-rate-dependent algorithm. By changing the slip partitioning between faults near the Main Central thrust and the Main Frontal thrust system at the Himalayan range front, …
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
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.
The Diachroneity Of Alluvial-Fan Lithostratigraphy?: A Test Case From Southeastern Ebro Basin Magnetostratigraphy, Nicholas Swanson-Hysell, David Barbeau
The Diachroneity Of Alluvial-Fan Lithostratigraphy?: A Test Case From Southeastern Ebro Basin Magnetostratigraphy, Nicholas Swanson-Hysell, David Barbeau
David L Barbeau Jr
Alluvial-fan strata contain valuable proxy data for kinematic, climatic and sediment-flux phenomena associated with high-relief source regions. Proper application of this data is dependent upon acquisition of accurate high-resolution chronostratigraphic data, best achieved through magnetostratigraphy. Collection of magnetostratigraphic and other proxy data from composite alluvial-fan sections assumes the chronostratigraphic significance of lithostratigraphy. We present the first test of this assumption with new magnetostratigraphy collected from Paleogene rocks of the southeastern Ebro basin. We report five new magnetostratigraphic sections that collectively sample 850 m of alluvial-fan and associated fluvial strata. One-hundred meters of lithostratigraphic overlap between these sections reveals equivalent magnetic …
In The Heat Of The Law, It's Not Just Steam: Geothermal Resources And The Impact On Thermophile Biodiversity, Donald J. Kochan, Tiffany Grant
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 …
Regional-Scale Mid-Jurassic To Late Cretaceous Unroofing From The Adirondack Mountains Through Central New England Based On Apatite Fission-Track And (U-Th)/He Thermochronology, Mary K. Roden-Tice, Steven J. Tice
Regional-Scale Mid-Jurassic To Late Cretaceous Unroofing From The Adirondack Mountains Through Central New England Based On Apatite Fission-Track And (U-Th)/He Thermochronology, Mary K. Roden-Tice, Steven J. Tice
Mary K. Roden-Tice
Apatite fission-track (AFT) ages of 178 to 70 Ma for 108 samples from the Adirondack Mountains and eastern New York State, Vermont, western Massachusetts and Connecticut, and western New Hampshire indicate that widespread unroofing occurred throughout the region during the Middle Jurassic to Late Cretaceous. Additionally, (U-Th)/He ages of 167 to 85 Ma were determined on nine of those samples and support cooling rates of 1.8°-2.2°C/m.yr. from 100° to 65°C during the Middle Jurassic to Late Cretaceous. Assuming a geothermal gradient of 25°C/km, unroofing rates for the region were estimated to be, on average, ∼0.07-0.08 km/m.yr. The AFT age discontinuities …
Preliminary Investigations Of Seasonal Changes In The Geochemical Evolution Of The Logdson River, Mammoth Cave, Kentucky, Chris Groves, Darlene M. Anthony, Joe Meiman
Preliminary Investigations Of Seasonal Changes In The Geochemical Evolution Of The Logdson River, Mammoth Cave, Kentucky, Chris Groves, Darlene M. Anthony, Joe Meiman
Chris Groves
Many geochemical studies have been made of karst waters worldwide. Most data that provide the framework for our current understanding of the evolution of karst waters have come from sampling at discrete times and locations, such as springs or wells. Relatively few studies have been made of the geochemical evolution of groundwater as it moves through an open flow system. This paper addresses the seasonal changes in the geochemistry of the Logsdon River conduit as it passes through nearly 10km of the carbonate aquifer of south-central Kentucky . The most important control on the ability of groundwaters to dissolve limestone …
Early Cretaceous Normal Faulting In Southern New England: Evidence From Apatite And Zircon Fission-Track Ages, Mary K. Roden-Tice, Robert P. Wintsch
Early Cretaceous Normal Faulting In Southern New England: Evidence From Apatite And Zircon Fission-Track Ages, Mary K. Roden-Tice, Robert P. Wintsch
Mary K. Roden-Tice
New apatite and zircon fission‐track (AFT, ZFT) ages from Mesozoic sediments and adjacent crystalline rocks from southern New England reveal age gradients from Middle Jurassic to Early Cretaceous. These gradients reflect the rotation of crustal blocks after the setting of the youngest AFT ages (∼140 Ma). The AFT ages of 168–98 Ma for 32 samples of Paleozoic metamorphic rocks east and west and within the Hartford Basin of Massachusetts and Connecticut indicate that unroofing in these regions occurred from Late Jurassic through Early Cretaceous. In both the Hartford Basin and rocks from crystalline terranes east of the basin, AFT ages …
Tectonic Synthesis Of The Olympic Mountains Segment Of The Cascadia Wedge, Using 2-D Thermal And Kinetic Modeling Of Isotopic Ages, Geoffrey E. Batt, Mark T. Brandon, Kenneth A. Farley, Mary K. Roden-Tice
Tectonic Synthesis Of The Olympic Mountains Segment Of The Cascadia Wedge, Using 2-D Thermal And Kinetic Modeling Of Isotopic Ages, Geoffrey E. Batt, Mark T. Brandon, Kenneth A. Farley, Mary K. Roden-Tice
Mary K. Roden-Tice
A fully coupled two-dimensional kinematic and thermal model of a steady state accretionary wedge, constrained by an extensive data set of fission track and (U-Th)/He ages for apatite and zircon, is here used to investigate the development of the Olympic Mountains segment of the Cascadia accretionary wedge. The model has two main free parameters: , the maximum rate of erosion for a generic erosion function operating at the top of the wedge, and α, the distribution of sedimentary accretion into the wedge. The best fit values for and α and their confidence limits are determined through an iterative search of …
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
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
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 …