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Articles 1201 - 1230 of 1881

Full-Text Articles in Earth Sciences

Combination Of Sar Remote Sensing And Gis For Monitoring Subglacial Volcanic Activity – Recent Results From Vatnajökull Ice Cap (Iceland), K. Scharrer, Rocco Malservisi, Ch. Mayer, O. Spieler, U. Münzer Nov 2007

Combination Of Sar Remote Sensing And Gis For Monitoring Subglacial Volcanic Activity – Recent Results From Vatnajökull Ice Cap (Iceland), K. Scharrer, Rocco Malservisi, Ch. Mayer, O. Spieler, U. Münzer

School of Geosciences Faculty and Staff Publications

This paper presents latest results from the combined use of SAR (Synthetic Aperture Radar) remote sensing and GIS providing detailed insights into recent volcanic activity under Vatnajökull ice cap (Iceland). Glaciers atop active volcanoes pose a constant potential danger to adjacent inhabited regions and infrastructure. Besides the usual volcanic hazards (lava flows, pyroclastic clouds, tephra falls, etc.), the volcano-ice interaction leads to enormous meltwater torrents (icelandic: jökulhlaup), devastating large areas in the surroundings of the affected glacier. The presented monitoring strategy addresses the three crucial questions: When will an eruption occur, where is the eruption site and which area is …

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Report On Mini-Workshop “Bringing Margins Science To The Classroom”, Cathy Manduca, Jeffrey G. Ryan, Don Reed Oct 2007

Report On Mini-Workshop “Bringing Margins Science To The Classroom”, Cathy Manduca, Jeffrey G. Ryan, Don Reed

Geology Faculty Publications

MARGINS has been awarded an NSF Course, Curriculum, and Laboratory Improvement (CCLI) grant to bring MARGINS research into widespread use in undergraduate teaching in ways that showcase the integrated, multidisciplinary approach that is characteristic of modern, front-line geoscience research. In collaboration with the Science Education Resource Center (SERC) at Carleton College, the project is developing a web-based collection of teaching materials referred to as “Mini-Lessons” (http://serc.carleton.edu/margins). Mini-Lessons range in scope from something as simple as the use of MARGINS science to illustrate a lecture to multi-day lab projects that capitalize on the MARGINS Data Repository. An exciting aspect of this …

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Shallow Slab Fluid Release Across And Along The Mariana Arc-Basin System: Insights From Geochemistry Of Serpentinized Peridotites From The Mariana Fore Arc, Ivan P. Savov, Jeffrey G. Ryan, Massimo D'Antonio, Patricia Fryer Sep 2007

Shallow Slab Fluid Release Across And Along The Mariana Arc-Basin System: Insights From Geochemistry Of Serpentinized Peridotites From The Mariana Fore Arc, Ivan P. Savov, Jeffrey G. Ryan, Massimo D'Antonio, Patricia Fryer

Geology Faculty Publications

Shallow slab devolatilization is not only witnessed through fluid expulsion at accretionary prisms, but is also evidenced by active serpentinite seamounts in the shallow fore-arc region of the Mariana convergent margin. Ocean Drilling Program (ODP) Leg 195 recovered serpentinized peridotites that present a unique opportunity to study the products of shallow level exchanges between the upper mantle and slab-derived fluids. Similar to samples recovered during ODP Leg 125, the protoliths of these fore-arc serpentinized peridotites are mantle harzburgites that have suffered large volume melt extraction (up to 25%) prior to interactions with fluids released from the downgoing Pacific Plate. Samples …

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Variable Intensity Of Teleconnections During The Late Holocene In Subtropical North America From An Isotopic Study Of Speleothem From Florida, Philip E. Van Beynen, Yemane Asmerom, Victor J. Polyak, Limaris R. Soto, Jason S. Polk Sep 2007

Variable Intensity Of Teleconnections During The Late Holocene In Subtropical North America From An Isotopic Study Of Speleothem From Florida, Philip E. Van Beynen, Yemane Asmerom, Victor J. Polyak, Limaris R. Soto, Jason S. Polk

School of Geosciences Faculty and Staff Publications

The persistence and influence of both tropical and extra‐tropical teleconnections on the hydrology of subtropical North America are little understood. Major atmospheric‐oceanic controls on the isotopic composition of the precipitation reconstructed from a 1,000 year old stalagmite are the North Atlantic Oscillation (NAO) and the Pacific Decadal Oscillation (PDO). These teleconnections create decadal‐ to centennial‐scale changes in the seasonal distribution of precipitation. An increase in the winter proportion of annual precipitation coincides with negative phase NAO conditions and a positive phase PDO. However, the PDO's influence appears to be weakened when it is out of phase with the El Niño …

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Cost/Effectiveness Analysis Of Obtaining Operational Estimates Of Reference Evapotranspiration, Peninsular Florida, Usa, Michael G. Kittridge Jul 2007

Cost/Effectiveness Analysis Of Obtaining Operational Estimates Of Reference Evapotranspiration, Peninsular Florida, Usa, Michael G. Kittridge

USF Tampa Graduate Theses and Dissertations

The objective of this study is to conduct a cost/effectiveness analysis of the computation of reference evapotranspiration (ETo) in the peninsular of Florida. A meteorological station on the Fort Meade Mine in Polk County, Florida was used to provide data for the calculation of ETo. Five ETo equations were tested to determine the accuracy and cost/effectiveness to the fully measured ASCE Penman-Monteith (Full ASCE-PM) equation on daily, monthly, and annually time steps. The ETo equations ranged in amounts of parameters from the Full ASCE-PM to the Hargreaves. The energy terms accounted for approximately 90% of the total ETo flux. Solar …

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Effect Of Regional Tectonic Setting On Local Fault Response To Episodes Of Volcanic Activity, Diana C. Roman, Philip Heron Jul 2007

Effect Of Regional Tectonic Setting On Local Fault Response To Episodes Of Volcanic Activity, Diana C. Roman, Philip Heron

Geology Faculty Publications

In this study we examine the interaction of tectonic and volcanically-generated stress fields, and their combined effect on patterns of volcanotectonic (VT) seismicity, by calculating Coulomb stress changes on local faults induced by a constant dike inflation event in a background stress field of systematically varying magnitude and orientation. We find that patterns of VT seismicity (earthquake locations and fault-plane solutions) resulting from dike inflation depend strongly on the relative strength and orientation of background tectonic stresses. Patterns of VT seismicity similar to those predicted by our Coulomb stress models have been observed at several recently active volcanoes, and appear …

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Hydrostratigraphy And Groundwater Migration Within Surficial Deposits At The North Lakes Wetland, Hillsborough County, Florida, Jason J. Laroche Jun 2007

Hydrostratigraphy And Groundwater Migration Within Surficial Deposits At The North Lakes Wetland, Hillsborough County, Florida, Jason J. Laroche

USF Tampa Graduate Theses and Dissertations

A wetland in west-central Florida was studied to characterize the local hydrostratigraphic configuration of surficial deposits overlying more-permeable limestones and conceptualize groundwater recharge. Eight continuous cores were drilled through the surficial deposits and partially into the underlying limestone. A total of 111 samples were extracted from the cores for laboratory sediment analyses and testing. The surficial deposits are roughly eight meters thick and made up of upper and lower clean-sand hydrostratigraphic layers (S1 and S3, respectively) separated by a low-permeability layer of clayey sand (S2). Also, a discontinuous low-permeability layer of clayey sand (S4) lies between S3 and the top …

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Along-Strike Trace Element And Isotopic Variation In Aleutian Island Arc Basalt: Subduction Melts Sediments And Dehydrates Serpentine, Brad S. Singer, Brian R. Jicha, William P. Leeman, Nick W. Rogers, Matthew F. Thirlwall, Jeffrey G. Ryan, Kirsten E. Nicolaysen Jun 2007

Along-Strike Trace Element And Isotopic Variation In Aleutian Island Arc Basalt: Subduction Melts Sediments And Dehydrates Serpentine, Brad S. Singer, Brian R. Jicha, William P. Leeman, Nick W. Rogers, Matthew F. Thirlwall, Jeffrey G. Ryan, Kirsten E. Nicolaysen

Geology Faculty Publications

Trace element and Sr-Nd-Pb isotope compositions of basaltic lavas from 11 volcanoes spanning 1300 km of the Aleutian Island arc provide new constraints on the recycling of elements in melts and fluids derived from subducted oceanic crust and sediment. Despite a nearly twofold variation in the flux of sediment subducted along the Aleutians, proxies indicating the presence of sediment melt in the magma source, including Th/La and Th/Nd, do not vary systematically along strike. In contrast, ratios including B/La, B/Nb, B/Be, Cs/La, Pb/Ce, and Li/Y suggest that the quantity or composition of fluid transferred from the slab into the mantle …

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Climatic And Structural Controls On The Geomorphology Of Wadi Sana, Highland Southern Yemen, Joshua Michael Anderson Apr 2007

Climatic And Structural Controls On The Geomorphology Of Wadi Sana, Highland Southern Yemen, Joshua Michael Anderson

USF Tampa Graduate Theses and Dissertations

Middle Holocene climate change forced significant environmental response and influenced human activities throughout southern Arabia. Climate models and proxy data indicate that climate along the southern Arabian peninsula changed from a moist phase, spanning the early to middle Holocene, to an arid phase, which persisted for the last ca. 5,000 years. A weakening and southward shift of the Southwest Indian Monsoon System, forced by northern hemisphere insolation variations in the precession band and/or glacial boundary conditions, is suggested as the mechanism for the abrupt shift to more arid conditions. Geoarchaeological evidence suggests that agriculture was more widespread and evolved alongside …

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Influence Of Evapotranspiration On Patterns Of Ground-Water Conductivity In Small Basins, Ana Jiménez Apr 2007

Influence Of Evapotranspiration On Patterns Of Ground-Water Conductivity In Small Basins, Ana Jiménez

USF Tampa Graduate Theses and Dissertations

Ground-water conductivity data were obtained from shallow wells in a 12 km2 stream-basin along a 400 m transect, extending from the divide to the stream. The stream, Pringle Branch, is a second-order perennial stream in Hillsborough County, Florida. The shallow stratigraphy consists of 2-3 m of fine sand over a layer of clayey silt and silty clay. Vegetation cover includes grasses on the upper and middle slope, and riparian woodlands on the foot slope and floodplain. Precipitation is about 1.3 m per year. Shallow ground-water conductivity is about 50 uS/cm at the divide. It increases moderately along the mid slope, …

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Geodetic, Teleseismic, And Strong Motion Constraints On Slip From Recent Southern Peru Subduction Zone Earthquakes, M. E. Pritchard, E. O. Norabuena, C. Ji, R. Boroschek, D. Comte, M. Simons, Timothy H. Dixon, P. A. Rosen Mar 2007

Geodetic, Teleseismic, And Strong Motion Constraints On Slip From Recent Southern Peru Subduction Zone Earthquakes, M. E. Pritchard, E. O. Norabuena, C. Ji, R. Boroschek, D. Comte, M. Simons, Timothy H. Dixon, P. A. Rosen

School of Geosciences Faculty and Staff Publications

We use seismic and geodetic data both jointly and separately to constrain coseismic slip from the 12 November 1996 Mw 7.7 and 23 June 2001 Mw 8.5 southern Peru subduction zone earthquakes, as well as two large aftershocks following the 2001 earthquake on 26 June and 7 July 2001. We use all available data in our inversions: GPS, interferometric synthetic aperture radar (InSAR) from the ERS-1, ERS-2, JERS, and RADARSAT-1 satellites, and seismic data from teleseismic and strong motion stations. Our two-dimensional slip models derived from only teleseismic body waves from South American subduction zone earthquakes with M …

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High Crystallinity Si-Ferrihydrite: An Insight Into Its Neel Temperature And Size Dependence Of Magnetic Properties, Thelma S. Berquo, Subir K. Banerjee, Robert G. Ford, R. Lee Penn, Thomas Pichler Feb 2007

High Crystallinity Si-Ferrihydrite: An Insight Into Its Neel Temperature And Size Dependence Of Magnetic Properties, Thelma S. Berquo, Subir K. Banerjee, Robert G. Ford, R. Lee Penn, Thomas Pichler

Geology Faculty Publications

Ferrihydrite, an antiferromagnetic iron oxyhydroxide with resulting magnetization due to uncompensated spins, is of great importance for the cycling of many trace metals in the environment. Four ferrihydrite samples prepared with 1.3 to 3.5 wt% of Si at different synthesis temperatures (7.5°C, 22°C, 50°C, and 75°C) were studied by temperature-dependent hysteresis loops, ZFC/FC susceptibility curves, ac susceptibility and Mössbauer spectroscopy. The incorporation of Si into the ferrihydrite during synthesis changed the properties of this mineral. Interestingly, seven sharp lines were observed in the X-ray diffraction pattern of the ferrihydrite samples prepared at 50°C and 75°C. In general, both XRD and …

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Temperature Anomalies In The Lower Suwannee River And Tidal Creeks, Florida, 2005, Ellen A. Raabe, Elzbieta Bialkowska-Jelinska Jan 2007

Temperature Anomalies In The Lower Suwannee River And Tidal Creeks, Florida, 2005, Ellen A. Raabe, Elzbieta Bialkowska-Jelinska

School of Geosciences Student Publications

Temperature anomalies in coastal waters were detected with Thermal Infrared imagery of the Lower Suwannee River (LSR) and nearshore tidal marshes on Florida’s Gulf Coast. Imagery included 1.5-m-resolution day and night Thermal Infrared (TIR) and 0.75-m-resolution Color Infrared (CIR) imagery acquired on 2-3 March 2005. Coincident temperature readings were collected on the ground and used to calibrate the imagery. The Floridan aquifer is at or near the land surface in this area and bears a constant temperature signature of ~ 22 degrees Celsius. This consistent temperature contrasts sharply with ambient temperatures during winter and summer months. Temperature anomalies identified in …

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Sedimentation Patterns In A Stabilized Migratory Inlet, Blind Pass, Florida, Ping Wang, David K. Tidwell, Tanya Beck, Nicholas C. Kraus Jan 2007

Sedimentation Patterns In A Stabilized Migratory Inlet, Blind Pass, Florida, Ping Wang, David K. Tidwell, Tanya Beck, Nicholas C. Kraus

Geology Faculty Publications

The shoaling rate in Blind Pass entrance channel approximately equals the net southward longshore sediment transport rate. Most of the shoaling occurs along the northern side of the channel. Flow measurements and numerical modeling reveal that the ebb current is approximately twice as strong in the thalweg along the south side as compared to the rest of the channel. In contrast, the flood current is mainly uniform across the inlet and is stronger than the ebb flow over the northern portion. This flow-velocity distribution induced by a nearly 90-deg bend of the channel contributes to the shoaling pattern. Two years …

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Data Report: Laboratory Testing Of Longshore Sand Transport By Waves And Currents; Morphology Change Behind Headland Structures, Mark B. Gravens, Ping Wang Jan 2007

Data Report: Laboratory Testing Of Longshore Sand Transport By Waves And Currents; Morphology Change Behind Headland Structures, Mark B. Gravens, Ping Wang

Geology Faculty Publications

Data from five series of movable bed laboratory experiments are presented herein. These experiments were conducted in the Largescale Sediment Transport Facility at the U.S. Army Engineer Research and Development Center, Vicksburg, MS. The data collected from these experiments are being used to improve longshore sand transport relationships under the combined influence of waves and currents and the enhancement of predictive numerical models of beach morphology evolution, in particular, with respect to modeling of tombolo development at detached breakwates and T-groins. These data were instrumental in the development and validation of GENESIS-T (Hanson et al. 2006) an enhanced version of …

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Petrographic And Geochemical Study On Cave Pearls From Kanaan Cave (Lebanon), Fadi H. Nader Jan 2007

Petrographic And Geochemical Study On Cave Pearls From Kanaan Cave (Lebanon), Fadi H. Nader

International Journal of Speleology

The Kanaan cave is situated at the coastal zone, north of Beirut City (capital of Lebanon). The cave is located within the upper part of the Jurassic Kesrouane Formation (Liassic to Oxfordian) which consists mainly of micritic limestone. Twenty seven cave pearls were subjected to petrographic (conventional and scanning electron microscopy) and geochemical analyses (major/trace elements and stable isotopes). The cave pearls were found in an agitated splash-pool with low mud content. They are believed to have formed through chemical precipitation of calcite in water over-saturated with calcium. The nucleus and micritic laminae show δ18OV-PDB values of …

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Seasonal Variations Of Co2 And 222Rn In A Mediterranean Sinkhole - Spring (Causse D’Aumelas, Se France), Christelle Batiot-Guilhe, Jean-Luc Seidel, Hervé Jourde, Olivier Hébrard, Vincent Bailly-Comte Jan 2007

Seasonal Variations Of Co2 And 222Rn In A Mediterranean Sinkhole - Spring (Causse D’Aumelas, Se France), Christelle Batiot-Guilhe, Jean-Luc Seidel, Hervé Jourde, Olivier Hébrard, Vincent Bailly-Comte

International Journal of Speleology

Carbon dioxide and 222Rn monitoring of the atmosphere of a Mediterranean sink hole - spring (SE France) during two hydrological cycles (from September 2004 to September 2006) showed seasonal variations with very high concentrations during summer (greater than 6% and 20 000 Bq/m3, respectively). Gas dynamics in caves often show seasonal variations. Meteorological parameters (barometric pressure and temperature mainly), cave geometry and fracture networks control exchanges between the cavity and outside atmosphere. Carbon dioxide and 222Rn may have different sources (atmosphere, soil, bedrock, deep gas diffusion, in situ oxidation of organic matter and, in some caves, …

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Kinematics Of The Nicaraguan Forearc From Gps Geodesy, Henry L. Turner, Peter Lafemina, Armando Saballos, Glen S. Mattioli, Pamela E. Jansma, Timothy H. Dixon Jan 2007

Kinematics Of The Nicaraguan Forearc From Gps Geodesy, Henry L. Turner, Peter Lafemina, Armando Saballos, Glen S. Mattioli, Pamela E. Jansma, Timothy H. Dixon

School of Geosciences Faculty and Staff Publications

Campaign GPS data from a network in the Nicaraguan forearc show a strong component of arc-parallel motion indicating northwest translation of a nearly rigid forearc sliver. Our measured mean velocity for forearc sites of 15.1 mm yr−1 agrees well with the arc-parallel sliver motion predicted previously by DeMets (2001) derived from closure constraints on oblique convergence between the Cocos and Caribbean plates. The lack of a northeasterly oriented arc-normal component of motion in forearc velocities indicates that there are complexities involved beyond a simple interpretation of sliver motion being driven by oblique convergence. The forearc is reasonably well-fit by …

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Observation Of Glacial Isostatic Adjustment In “Stable” North America With Gps, Giovanni F. Sella, Seth Stein, Timothy H. Dixon, Michael Craymer, Thomas S. James, Stephane Mazzotti, Roy K. Dokka Jan 2007

Observation Of Glacial Isostatic Adjustment In “Stable” North America With Gps, Giovanni F. Sella, Seth Stein, Timothy H. Dixon, Michael Craymer, Thomas S. James, Stephane Mazzotti, Roy K. Dokka

School of Geosciences Faculty and Staff Publications

Motions of three hundred and sixty Global Positioning System (GPS) sites in Canada and the United States yield a detailed image of the vertical and horizontal velocity fields within the nominally stable interior of the North American plate. By far the strongest signal is the effect of glacial isostatic adjustment (GIA) due to ice mass unloading during deglaciation. Vertical velocities show present-day uplift (∼10 mm/yr) near Hudson Bay, the site of thickest ice at the last glacial maximum. The uplift rates generally decrease with distance from Hudson Bay and change to subsidence (1–2 mm/yr) south of the Great Lakes. The …

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Speleothems As Indicators Of Wet And Dry Periods, Ian John Fairchild, Emily Anne Mcmillan Jan 2007

Speleothems As Indicators Of Wet And Dry Periods, Ian John Fairchild, Emily Anne Mcmillan

International Journal of Speleology

Calcareous speleothems provide a record of dripwater composition which in turn is a function of climatic conditions. The historical focus of speleothem palaeoclimate studies has been on the derivation of palaeotemperatures through oxygen isotope studies. However, it is now realized that water availability is a more generally important control on their characteristics. Growth rate and growth morphology in principle should give rise to recognizable changes at low flow. However, accidental plumbing effects during aquifer evolution, can also lead to variations in water supply and it is not easy to distinguish these effects. In areas where there is a strong amount …

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Acadian Biospeleology: Composition And Ecology Of Cave Fauna Of Nova Scotia And Southern New Brunswick, Canada, Max Moseley Jan 2007

Acadian Biospeleology: Composition And Ecology Of Cave Fauna Of Nova Scotia And Southern New Brunswick, Canada, Max Moseley

International Journal of Speleology

The vertebrate and invertebrate fauna, environment and habitats of caves and disused mines in Nova Scotia and southern New Brunswick are provisionally catalogued and described, based on field collections made over many years. The area was glaciated and the subterranean fauna consists of non-troglobites all of which have arrived and colonised the caves during or following final recession of the Pleistocene glaciers. The statistical composition of the fauna at the higher taxonomic level is similar to that in Ontario, but is less species rich and there are some notable ecological and other differences. Porcupine dung accumulations are an important habitat …

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The Polygenetic Caves Of Cuatro Ciénegas (Coahuila, Mexico): Morphology And Speleogenesis, Leonardo Piccini, Paolo Forti, Italo Giulivo, Marco Mecchia Jan 2007

The Polygenetic Caves Of Cuatro Ciénegas (Coahuila, Mexico): Morphology And Speleogenesis, Leonardo Piccini, Paolo Forti, Italo Giulivo, Marco Mecchia

International Journal of Speleology

The Cuatro Ciénegas area is renown worldwide for its thermal springs, which feed a unique ecosystem consisting of many pools, lakes and marshes. The pools also represent a very important water resource in a region characterized by scarce rainfalls. Field investigation has emphasized the role of karst in the hydrogeology of the area. Only few and restricted forms of surface karst are represented; caves are mainly relics of old speleogenetic phases of thermal and bathyphreatic water flow.

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Sails: A New Gypsum Speleothem From Naica, Chihuahua, Mexico, Tullio Bernabei, Paolo Forti, Roberto Villasuso Jan 2007

Sails: A New Gypsum Speleothem From Naica, Chihuahua, Mexico, Tullio Bernabei, Paolo Forti, Roberto Villasuso

International Journal of Speleology

The caves of Naica (Chihuahua, Mexico) are perhaps the most famous mine caves of the world due to the presence of gigantic gypsum crystals. Nevertheless, very little research has been carried out on this karst area until now. A multidisciplinary investigation started in 2006 with the aim not only to define the genesis and the age of the Naica gypsum crystals, but also on other scientific aspects of these caves. This paper describes a completely new type of gypsum speleothem: the “sails”, observed only inside the Cueva de las Velas, one of the caves of the Naica system. This speleothem …

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Bomb-Spike Dating Of A Mummified Baboon In Ludwig Cave, Namibia, Greg Hodgins, George A. Brook, Eugene Marais Jan 2007

Bomb-Spike Dating Of A Mummified Baboon In Ludwig Cave, Namibia, Greg Hodgins, George A. Brook, Eugene Marais

International Journal of Speleology

In 1982 a mummified adult female baboon was discovered on a ledge in Ludwig Cave in Namibia. A toe bone was removed for dating in July 1995. AMS radiocarbon dating of bone collagen, tendon, and skin indicates a post-modern age. Application of the atomic bomb-spike calibration curve suggests death in late 1977 and an age at death of around 19 years. Baboons roost in the cave and the mummified female, along with a mummified juvenile male discovered in 2002 and three rotting corpses discovered in 1995, were probably chased by other baboons or by leopards down a ca. 6 m …

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Eogenetic Karst, Glacioeustatic Cave Pools And Anchialine Environments On Mallorca Island: A Discussion Of Coastal Speleogenesis, Angel Ginés, Joaquín Ginés Jan 2007

Eogenetic Karst, Glacioeustatic Cave Pools And Anchialine Environments On Mallorca Island: A Discussion Of Coastal Speleogenesis, Angel Ginés, Joaquín Ginés

International Journal of Speleology

Coastal karst is characterized by special geomorphologic and hydrodynamic conditions as well as by peculiar sedimentary, geochemical, and biospeleological environments. Generally, the more distinctive karstic features produced near the coastline are strongly influenced by sea-level changes, which generate a broad set of interactions between littoral processes and karst development. The glacioeustatic rises and falls of sea level affected the littoral karst in different ways, namely: vertical and horizontal shifts in the shoreline position, changes in elevation of the local water table, and vertical displacements of the halocline. Most eogenetic karsts have been subjected over long time spans to repeated changes …

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Climatic Differences And Similarities Between Indian And East Asian Monsoon Regions Of China Over The Last Millennium: A Perspective Based Mainly On Stalagmite Records, Ming Tan Jan 2007

Climatic Differences And Similarities Between Indian And East Asian Monsoon Regions Of China Over The Last Millennium: A Perspective Based Mainly On Stalagmite Records, Ming Tan

International Journal of Speleology

Cave sediments, especially stalagmites, have been providing absolute dated climate records that can extend from the present to over 500,000 years ago. Based on the reconstructed temperature time series, a comprehensive overview of the climatic differences and similarities between the Indian and the East Asian Monsoon regions of China over the last millennium is presented. Evidence from accurately dated and high-resolution records including stalagmites, ice cores and tree rings show that there was a “Medieval Warm Period” (around 1000 to 1400 AD) in north and east China where climate is dominated by the East Asian monsoon; whilst no such interval …

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The Impact Of Host Rock Geochemistry On Bacterial Community Structure In Oligotrophic Cave Environments, Hazel A. Barton, Nicholas M. Taylor, Michael P. Kreate, Austin C. Springer, Stuart A. Oehrle, Janet L. Bertog Jan 2007

The Impact Of Host Rock Geochemistry On Bacterial Community Structure In Oligotrophic Cave Environments, Hazel A. Barton, Nicholas M. Taylor, Michael P. Kreate, Austin C. Springer, Stuart A. Oehrle, Janet L. Bertog

International Journal of Speleology

Despite extremely starved conditions, caves contain surprisingly diverse microbial communities. Our research is geared toward understanding what ecosystems drivers are responsible for this high diversity. To asses the effect of rock fabric and mineralogy, we carried out a comparative geomicrobiology study within Carlsbad Cavern, New Mexico, USA. Samples were collected from two different geologic locations within the cave: WF1 in the Massive Member of the Capitan Formation and sF88 in the calcareous siltstones of the Yates Formation. We examined the organic content at each location using liquid chromatography mass spectroscopy and analyzed microbial community structure using molecular phylogenetic analyses. In …

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A Taxonomic Survey Of Lamp Flora (Algae And Cyanobacteria) In Electrically Lit Passages Within Mammoth Cave National Park, Kentucky, Thomas Smith, Rick Olson Jan 2007

A Taxonomic Survey Of Lamp Flora (Algae And Cyanobacteria) In Electrically Lit Passages Within Mammoth Cave National Park, Kentucky, Thomas Smith, Rick Olson

International Journal of Speleology

A taxonomic survey of the lamp flora from electrically lit passages in Mammoth Cave, Mammoth Cave National Park, identified 28 species. Overall, cyanobacteria were dominant represented by 14 species (50% of the total), green algae had eight species (29%), and six diatoms species (21%) were present. There was not a correlation between species diversity and temperature, but there is a general trend of increasing diversity with warmer temperatures. There were two algal or cyanobacterial species identified in this study that overlapped with previous studies. There is a lack of continuity between previous studies only having one species identified in more …

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Tectonic Control Of Subsidence And Southward Displacement Of Southeast Louisiana With Respect To Stable North America, Roy K. Dokka, Giovanni F. Sella, Timothy H. Dixon Dec 2006

Tectonic Control Of Subsidence And Southward Displacement Of Southeast Louisiana With Respect To Stable North America, Roy K. Dokka, Giovanni F. Sella, Timothy H. Dixon

School of Geosciences Faculty and Staff Publications

GPS data collected between 1995 and 2006 suggest that southeast Louisiana, including New Orleans and the larger Mississippi Delta, are both subsiding vertically and moving southward with respect to stable North America. Both motions are likely related due to their common tectonic setting. Subsidence in the New Orleans area occurs in part because it is located in the hanging wall of a large listric normal fault system that forms the northern boundary of a 7–10 km thick allochthon that is detached from stable North America. Southward motion of this allochthon relative to stable North America occurs at 2.2 ± 0.6 …

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Sinkhole Structure Imaging In Covered Karst Terrain, Sarah E. Kruse, M. Grasmueck, Matthew Weiss, D. Viggiano Aug 2006

Sinkhole Structure Imaging In Covered Karst Terrain, Sarah E. Kruse, M. Grasmueck, Matthew Weiss, D. Viggiano

Geology Faculty Publications

Ground penetrating radar (GPR) and resistivity techniques have been widely used to map the locations of sinkholes in covered karst terrain. To determine whether a sinkhole is a likely preferential conduit for groundwater flow, however, requires higher-resolution imaging than that used in conventional sinkhole mapping surveys. Field observations combined with simulated surveys for a 15-m diameter 3-m deep sinkhole in west-central Florida are used to assess the resolution of GPR and resistivity surveys targeting the semiconfining unit that floors the sinkhole depression. 2D resistivity surveys clearly show the central depression as well as resistivity contrasts between the cover sediments within …

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