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Articles 1 - 28 of 28
Full-Text Articles in Geology
Early Miocene Antarctic Glacial History: New Insights From Heavy Mineral Analysis From Andrill And–2a Drill Core Sediments, Francesco Iacoviello, Giovanna Giorgetti, Isabella Turbanti Memmi, Sandra Passchier
Early Miocene Antarctic Glacial History: New Insights From Heavy Mineral Analysis From Andrill And–2a Drill Core Sediments, Francesco Iacoviello, Giovanna Giorgetti, Isabella Turbanti Memmi, Sandra Passchier
Sandra Passchier
The present study deals with heavy mineral analysis of late Early Miocene marine sediments recovered in the McMurdo Sound region (Ross Sea, Antarctica) during the ANDRILL— SMS Project in 2007. The main objective is to investigate how heavy mineral assemblages reflect different source rocks and hence different provenance areas. These data contribute to a better understanding of East Antarctica ice dynamics in the Ross Sea sector during the Early Miocene (17.6–20.2 Ma), a time of long-term global warming and sea level rise. The AND-2A drill core recovered several stratigraphic intervals that span from Early Miocene to Pleistocene and it collected …
Paleogeographic, Paleoceanographic, And Tectonic Controls On Early Late Ordovician Graptolite Diversity Patterns, Daniel Goldman, Shuang-Ye Wu
Paleogeographic, Paleoceanographic, And Tectonic Controls On Early Late Ordovician Graptolite Diversity Patterns, Daniel Goldman, Shuang-Ye Wu
Shuang-ye Wu
The Katian Age (early Late Ordovician) was a time of significant decline in marine biodiversity, but whether this decline was a real phenomenon or an artifact of the relatively few studies devoted to this interval requires further research. We examined the pattern of graptolite faunal changes across the boundary between the Climacograptus bicornis and Diplacanthograptus caudatus graptolite zones in North America and on several other continents.
A sharp decline in species diversity occurs in the Appalachian Basin. Scores for normalized diversity dropped from 20 in the C. bicornis Zone to 7 in the D. caudatus Zone. Only 11% of the …
Stable Isotope Studies Of Paleoenvironment And Paleoclimate From Afar, Ethiopia, Zelalem K. Bedaso
Stable Isotope Studies Of Paleoenvironment And Paleoclimate From Afar, Ethiopia, Zelalem K. Bedaso
Zelalem Bedaso
ABSTRACT The sedimentary deposits of the Hadar Formation at Dikika and the Mount Galili Formation at Galili preserve a wealth of paleoenvironmental and paleoclimatic records spanning the last 5.29 Ma. Stable carbon and oxygen isotopic compositions of herbivore tooth enamel were analyzed for more than 600 specimens of 15 different taxa from 10 stratigraphic intervals. The application of carbon and oxygen isotopes here aims principally at reconstructing shifts in the relative abundance of C4 grasses, and its implications for climate indicators including temperature, aridity, and seasonality. The full range of δ13Cenamel values throughout the Plio-Pleistocene signifies a wide range of …
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 …63>
Temporal And Spatial Evolution Of Wave-Induced Ripple Geometry: Regular Versus Irregular Ripples, Timothy Nelson, George Voulgaris
Temporal And Spatial Evolution Of Wave-Induced Ripple Geometry: Regular Versus Irregular Ripples, Timothy Nelson, George Voulgaris
George Voulgaris
Concurrent observations of inner shelf near bed hydrodynamics and acoustic imagery of the seabed are used to relate wave-induced ripple geometry (wavelength and orientation) to near bed directional wave velocities. The observations were collected on the continental shelf of the South Atlantic Bight at water depths of 9.5 and 30 m off the coasts of South Carolina (median size 177 mm) and Georgia (388 mm), respectively. 2-D spectral analysis techniques are performed on the imagery to automate detection of ripple wavelength, orientation, and irregularity. Our analysis shows that ripple irregularity is a time-dependent process dependent on magnitude, direction, and duration …
Updated Glacial Chronology Of The South Fork Hoh River Valley, Olympic Peninsula, Washington Through Detailed Stratigraphy And Osl Dating, Cianna E. Wyshnytzky, Tammy M. Rittenour, Glenn D. Thackray
Updated Glacial Chronology Of The South Fork Hoh River Valley, Olympic Peninsula, Washington Through Detailed Stratigraphy And Osl Dating, Cianna E. Wyshnytzky, Tammy M. Rittenour, Glenn D. Thackray
Cianna E Wyshnytzky
Four glacial advances are preserved and exposed in the stratigraphy of the South Fork Hoh River valley. The oldest of these advances extended beyond the South Fork valley into the Hoh River valley. The three younger advances are preserved in the stratigraphy cut bank exposures in the valley and geomorphically by moraines and outwash plains. One of these advances represents a re-advance to the same terminal position of the previous advance and has not previously been recognized in this valley or other glaciated valleys in the western Olympic Mountains. This finding advocates for a detailed sedimentologic and stratigraphic approach to …
Biogeochemical Evidence For Hydrologic Change During The Holocene In A Lake Sediment Record From Southeast Greenland, Nicholas L. Balascio, William J. D'Andrea, Raymond S. Bradley, Bianca B. Perren
Biogeochemical Evidence For Hydrologic Change During The Holocene In A Lake Sediment Record From Southeast Greenland, Nicholas L. Balascio, William J. D'Andrea, Raymond S. Bradley, Bianca B. Perren
Raymond S Bradley
Holocene paleoclimate records from Greenland help us understand the response of the Greenland Ice Sheet and regional oceanic and atmospheric circulation systems to natural climate variability in order to place recent changes in a longer-term perspective. Here biogeochemical analysis of a lake sediment core from southeast Greenland is used to define changes in moisture balance and runoff during the Holocene in a catchment near the margin of the Greenland Ice Sheet. A 1.6 m sediment core that spans the last 8.8 ka was recovered from Flower Valley Lake on Ammassalik Island. Magnetic susceptibility, diatoms, bulk biogeochemical properties (TOC, C/N, δ13Corg), …
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 …
The Southeastern Coastal Plain: An Overview, Lee J. Florea, H L. Vacher
The Southeastern Coastal Plain: An Overview, Lee J. Florea, H L. Vacher
Lee J Florea, PhD, P.G.
Florida enjoys the highest density of large springs in North America (Scott et al., 2004); Silver Springs is just one of the 33 first-magnitude springs (mean flow greater than 100 cfs (2.8 m3/s), and there are hundreds of smaller springs (Fig. 6.2; see Meinzer, 1927, and Scott et al., 2004). They are supplied by spectacular underwater caves that are internationally recognized in the cave-diving community. Less well known are the many air-filled caves of the region (see Florea, 2006; Moore, 2006; Lane 1986). Though generally smaller than their aquatic counterparts, their beauty can rival the world’s best show caves. This …
The Cumberland Plateau Of Eastern Kentucky, Larry C. Simpson, Lee J. Florea
The Cumberland Plateau Of Eastern Kentucky, Larry C. Simpson, Lee J. Florea
Lee J Florea, PhD, P.G.
Eastern Kentucky contains almost the same Mississippian limestones that appear at Mammoth Cave in south-central Kentucky (Chapter 3). To the east these strata dip below the Appalachian Basin and reappear as the Greenbrier Group in the Virginias. The limestone outcrop in eastern Kentucky follows the western margin of the Cumberland Plateau and forms a ragged ribbon of karst that is continuous from southeastern Ohio through Kentucky and Tennessee and into northern Alabama. There are more than 2,000 documented caves comprising over 470 km of surveyed passage in the Kentucky segment of the Cumberland Plateau (Fig. 2.115). At least 14 are …
Caves And Karst Of West-Central Florida, Lee J. Florea, David Budd, Robert Brinkmann
Caves And Karst Of West-Central Florida, Lee J. Florea, David Budd, Robert Brinkmann
Lee J Florea, PhD, P.G.
The real west-central Florida is far from the “Sunshine State” image of white sand beaches and palm trees. Gently rolling hills, dense jungle-like forests, pine and palmetto scrublands, impenetrable cypress swamps, and alligator-laden rivers are more common. Numerous crystal-clear springs offer a glimpse of the hidden world below – a world that could challenge the most imaginative Disney artists (Fig. 6.17).
The Biscayne Aquifer Of Southeastern Florida, Kevin Cunningham, Lee J. Florea
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.
Geology And Hydrology Of Karst In West-Central And North-Central Florida, Lee J. Florea
Geology And Hydrology Of Karst In West-Central And North-Central Florida, Lee J. Florea
Lee J Florea, PhD, P.G.
The state of Florida is blessed with the highest density of large springs in North America and hundreds of smaller springs where the water from limestone aquifers returns to the surface (Scott et al., 2004). Spectacular underwater caves supply water to these springs. Lesser known are the equally fantastic air-filled caves of Florida and South Georgia (Florea, 2006; Lane, 1986). This paper features these underwater and airfilled caves, explores the impact of changes in sea level on karst in this near-coastal environment, and establishes several geologic and hydrologic characteristics that distinguish karst in the limestones of the southeast from karst …
Visualization Of Groundwater Flow Within Touching-Vug And Matrix Porosity In An Eogenetic Karst Aquifer, Lee J. Florea, Kevin J. Cunningham, Stephen Altobelli
Visualization Of Groundwater Flow Within Touching-Vug And Matrix Porosity In An Eogenetic Karst Aquifer, Lee J. Florea, Kevin J. Cunningham, Stephen Altobelli
Lee J Florea, PhD, P.G.
In this study, we use an innovative, non-invasive technology, nuclear magnetic resonance imaging (NMRI), to visualize the direction and magnitude of groundwater flow in field samples of late Pleistocene limestone of the Biscayne aquifer. Specific goals of the first set of NMRI experiments are to map the advective velocity of water flowing at two rates of specific discharge (0.00025 and 0.00013 m/s) through a 10-cm-diameter cylindrical, epoxy-resin model. The model interior accurately reproduces a well-connected maze of ichnologically influenced, centimeter-scale, touching-vug macroporosity common within preferred flow zones in parts of the Biscayne aquifer. A second set of NMRI experiments investigates …
Focus Group On Karst Hydrology - Conceptual Models, Aquifer Characterization, And Numerical Modeling, Martin Sauter, Lee J. Florea, Others
Focus Group On Karst Hydrology - Conceptual Models, Aquifer Characterization, And Numerical Modeling, Martin Sauter, Lee J. Florea, Others
Lee J Florea, PhD, P.G.
No abstract provided.
Biogenic Porosity And Its Lattice Boltzmann Method Permeability In The Karst Biscayne Aquifer, Kevin Cunningham, Mike Sukop, Haibo Huang, Pedro Alvarez, Allen Curran, Michael Waker, Lee J. Florea, Robert Renken, Joann F. Dixon
Biogenic Porosity And Its Lattice Boltzmann Method Permeability In The Karst Biscayne Aquifer, Kevin Cunningham, Mike Sukop, Haibo Huang, Pedro Alvarez, Allen Curran, Michael Waker, Lee J. Florea, Robert Renken, Joann F. Dixon
Lee J Florea, PhD, P.G.
No abstract provided.
International, Cooperative Research In The Apuseni Mountains Of Western Romania, Lee J. Florea, Bogdan P. Onac
International, Cooperative Research In The Apuseni Mountains Of Western Romania, Lee J. Florea, Bogdan P. Onac
Lee J Florea, PhD, P.G.
In May of 2006, nine American scientists and cavers from the Karst Research Group at the University of South Florida traveled to western Romania to attend and present at an international conference on records of climate change in caves in the historic Roman town of Baile Hurculane. The conference, co-sponsored by the “Emil Racoviţă” Speleological Institute of Romania and the Karst Waters Institute, drew more than 100 experts in the field of climate change and karst, and was a wonderful time spent alongside the thermal springs and Austro-Hungarian bathhouses nestled within the massive limestone canyon of the Cerna River. Following …
The Karst Of West-Central Florida, Lee J. Florea
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).
Architecture Of Air-Filled Caves Within The Karst Of The Brooksville Ridge, West-Central Florida, Lee J. Florea
Architecture Of Air-Filled Caves Within The Karst Of The Brooksville Ridge, West-Central Florida, Lee J. Florea
Lee J Florea, PhD, P.G.
Air-filled caves surveyed in the Brooksville Ridge of west-central Florida provide insight into the organization of karstic permeability within the unconfined portions of the Upper Floridan Aquifer. The morphology of the passages that compose these caves in geologically young, high-permeability limestones is strikingly different from caves found in ancient carbonates far from the influence of the coast. Cave passages in west-central Florida are laterally extensive and tiered. Principal horizons of cave development occur between +3 m and +5 m, +12 m and +15 m, and +20 m and +22 m above modern sea level. The primary guide of cave passage …
Morphologic Features Of Conduits And Aquifer Response In The Unconfined Floridan Aquifer System, West Central Florida, Lee J. Florea, H L. Vacher
Morphologic Features Of Conduits And Aquifer Response In The Unconfined Floridan Aquifer System, West Central Florida, Lee J. Florea, H L. Vacher
Lee J Florea, PhD, P.G.
Conduits within the unconfined Floridan Aquifer of west-central Florida include both horizontal and vertical components. In this paper, we investigate each and propose theories based upon cave survey data and a collection of over 300 Florida cave maps. First, we find that vertical portions of conduits visually correlate to fractures, and these fractures tend to be the dominant control of conduit directionality. Length-weighted rose diagrams of passage directions reveal a NW-SE and NE-SW pattern of conduit directions statistically similar to results found in remote sensing studies of photolinears. Secondly we note that horizontal elements of conduits occur at consistent horizons …
Le Voragini Catastrofiche Della Florida, Lee J. Florea, Robert Brooks, Tom Turner, Mario Parise
Le Voragini Catastrofiche Della Florida, Lee J. Florea, Robert Brooks, Tom Turner, Mario Parise
Lee J Florea, PhD, P.G.
The West-Central Florida landscape is worlds away from white-sand beaches and palm trees: gentle rolling hills, dense jungle-like forests, pine tree and palmetto scrub lands, impenetrable cypress swamps, and alligator-laden rivers. Numerous crystal-clear springs offer a glimpse of the hidden world below these wildly-diverse ecosystems. Internationally recognized in the cave diving community, Florida harbors some of the longest and most spectacular underwater cave systems. Lesser known are Florida’s “dry” caves, that rarely have large natural openings and, though often smaller than their aquatic counterparts, the beauty found within can rival the world’s best show-caves. Little was known about caves and …
Cave Levels, Marine Terraces, Paleoshorelines, And The Water Table In Peninsular Florida, Lee J. Florea, H L. Vacher
Cave Levels, Marine Terraces, Paleoshorelines, And The Water Table In Peninsular Florida, Lee J. Florea, H L. Vacher
Lee J Florea, PhD, P.G.
Levels of passages are a common feature of many cave systems around the world. Likewise, coastal and marine terraces are common in coastal plain settings. This paper extends the discussion of cave levels from traditional research sites in the interior lowlands of the United States to the Atlantic Coastal Plains, namely peninsular Florida. Are there levels in Florida caves, and is there a link between the elevation of cave levels, marine terraces, paleoshorelines, and thus the water table, above and below present sea level in peninsular Florida?
The 2004 Vaca Pateau Geoarcheology Expedition - Belize, Lee J. Florea, Beth Fratesi, Philip Reeder, Amber Yuellig
The 2004 Vaca Pateau Geoarcheology Expedition - Belize, Lee J. Florea, Beth Fratesi, Philip Reeder, Amber Yuellig
Lee J Florea, PhD, P.G.
No abstract provided.
Light & Dark: The Hidden Wonders Of Buck Creek, Lee J. Florea
Light & Dark: The Hidden Wonders Of Buck Creek, Lee J. Florea
Lee J Florea, PhD, P.G.
As early morning mists rise from the banks of its supple waters, beams of light penetrate the Buck Creek valley illuminating its beauty. While light illuminates most of the land, there are secret places, nestled within the forest where darkness reigns supreme. Places beyond the touch of the sun, beyond the influence of seasons. Here time is measured not in cycles of light but by the flow of water and fall of rock. These are the caves, conduits for water past and present. Nestled in the hills of south-central Kentucky the caves along Buck Creek provide the lifeblood for a …
Sedimentation And Porosity Enhancement In A Breached Flank Margin Cave, Lee J. Florea, John Mylroie, Adam Price
Sedimentation And Porosity Enhancement In A Breached Flank Margin Cave, Lee J. Florea, John Mylroie, Adam Price
Lee J Florea, PhD, P.G.
No abstract provided.
Solute Transport Through Laboratory-Scale Karstic Aquifers, Lee J. Florea, Carol M. Wicks
Solute Transport Through Laboratory-Scale Karstic Aquifers, Lee J. Florea, Carol M. Wicks
Lee J Florea, PhD, P.G.
Laboratory-scale models of branchwork and of network karstic aquifers were constructed to provide data needed for calibration of numerical models. The distribution and connectedness of the conduits and sinkholes were scaled similarly to those found in nature; however, the porosity of models (2 and 3%) and the recharge rate (80 cm/hr) could not be scaled appropriately. Pulses of 1-M NaCl were injected sequentially at ten locations on both models to determine transport parameters using QTRACER. For all experiments, the Reynolds numbers were <150, the Peclet numbers were >6, and the Froude numbers were ~0. The flow regime was laminar and subcritical and advective processes dominated …150,>
Karst Genetic Model For The French Bay Breccia Deposits, San Salvador, Bahamas, Lee J. Florea, John Mylroie, Jim Carew
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.
How Synchronous Are Neogene Marine Plankton Events?, Cinzia Spencer-Cervato, Hans R. Thierstein, David B. Lazarus, Jean-Pierre Beckmann
How Synchronous Are Neogene Marine Plankton Events?, Cinzia Spencer-Cervato, Hans R. Thierstein, David B. Lazarus, Jean-Pierre Beckmann
Cinzia Cervato
An electronic supplement of this material may be obtained on adiskette or Anonymous FTP from KOSMOS.AGU.ORG. (LOGIN toAGU's FTP account using ANONYMOUS as the username andGUEST as the password. Go to the right directory by typing CDAPEND. Type LS to see what files are available. Type GET and thename of the file to get it. Finally, type EXIT to leave the system.)(Paper 94PA01456, How synchronous are Neogene marine planktonevents?, by C. Spencer-Cervato, H. R. Thierstein, D. B. Lazarus, andJ-P Beckmann). Diskette may be ordered from American GeophysicalUnion, 2000 Florida Avenue, N.W., Washington, DC 20009; $15.00.Payment must accompany order. We analyzed …