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Assessing The Reproducibility Of Coral Oxygen And Carbon Isotope Time Series From Fiji And Tonga And Their Application To The Reconstruction Of South Pacific Convergence Zone Movements Since The Mid-1800s, Emilie Pauline Dassie
Assessing The Reproducibility Of Coral Oxygen And Carbon Isotope Time Series From Fiji And Tonga And Their Application To The Reconstruction Of South Pacific Convergence Zone Movements Since The Mid-1800s, Emilie Pauline Dassie
Geology Theses and Dissertations
A major feature affecting the hydrology of the southern hemisphere is the South Pacific Convergence Zone (SPCZ); a band of high rainfall extending southeastward from the Western Pacific Warm Pool (WPWP). It is a key source of atmospheric water vapor and latent heating. While it is clear that the SPCZ plays a fundamental role in Earth's climate, little is known about the patterns and mechanisms responsible for interannual to century-scale changes in its position and how it may respond to global climate change. This research was focused on developing precisely dated, coral-derived geochemical records of SPCZ variability over the last …
Western Equatorial Pacific Climate Variability From Restricted Basins: Century Scale Changes In Kau Bay To Glacial-Interglacial Changes In The Sulu Sea, Samantha J. Langton
Western Equatorial Pacific Climate Variability From Restricted Basins: Century Scale Changes In Kau Bay To Glacial-Interglacial Changes In The Sulu Sea, Samantha J. Langton
Geology Theses and Dissertations
The surface ocean in the western equatorial Pacific contains some of the warmest water on the planet in the western Pacific warm pool (WPWP). Changes in the size and scope of the warm pool have a significant impact on global climate. With the concern of changes in the extent of this body of water as a result of anthropomorphic changes in atmospheric composition, it is vital to investigate prior changes to the WPWP, the causes of such changes, and resultant effects. For my dissertation, I used several proxies to analyze sediments from Kau Bay and the Sulu Sea in Indonesia …
Assessing Replicated Coral Trace Element (Sr/Ca And Mg/Ca) Variability And Skeletal Growth Records From The Tropical Pacific, Henry Chun-Yi Wu
Assessing Replicated Coral Trace Element (Sr/Ca And Mg/Ca) Variability And Skeletal Growth Records From The Tropical Pacific, Henry Chun-Yi Wu
Geology Theses and Dissertations
To gain a more complete history and understanding of the full amplitude of climate variability prior to instrumental records, science must rely on natural proxy archives that are sensitive to fluctuations in key climate parameters. Calcium carbonate skeletons of long-living hermatypic corals in some locations have been shown to be natural archives of surface ocean variability. This study investigated the fidelity and reproducibility of coral derived Sr/Ca time series from Clipperton Atoll, Fiji, and Tonga as accurate proxies of sea surface temperature (SST). The replicated high-resolution Sr/Ca time series record monthly and bimonthly SST changes, though with a greater magnitude …
The Effect Of Vegetated Roofs On Acid Precipitation Runoff, Jennifer Gillen
The Effect Of Vegetated Roofs On Acid Precipitation Runoff, Jennifer Gillen
Geology Theses and Dissertations
Vegetated, or “green” roofs are used in urban architecture and sustainable building to capture stormwater and enhance urban wildlife. Most research to date has focused on their water retention capabilities, but green roofs also have the potential to treat anthropogenic acid precipitation in urban environments. More specifically, green roofs could reduce sulfate, nitrate and hydrogen ion concentrations in runoff. One previous study has demonstrated that nitrate was reduced in water draining from a green roof (Berndtsson, et al. 2006), but this unpublished thesis appears to be the first comprehensive study of the effects of vegetated roof materials on major ions …
Metal Concentrations In Native Yupik Foodstuffs From St. Lawrence Island, Alaska, Judith Kricheff
Metal Concentrations In Native Yupik Foodstuffs From St. Lawrence Island, Alaska, Judith Kricheff
Geology Theses and Dissertations
The Yupik people of St. Lawrence Island, Alaska have a traditional subsistence lifestyle with the majority of their diet consisting of local birds, fish, seal, walrus, and whale. Diets based on fish and marine mammals, such as the Yupik diet, are potential pathways for exposure to mercury and other toxic metals. At St. Lawrence Island, metal contaminants may come from local sources such as weathered rock or two abandoned U.S. military bases or remote sources through atmospheric deposition or seasonal migration of animals to the island.
The main goals of this study are to determine the total concentrations of copper …
Mercury Uptake By Aquatic Macrophytes In Urban And Rural Watersheds, Albany County, Ny, Bernd G. Neumann
Mercury Uptake By Aquatic Macrophytes In Urban And Rural Watersheds, Albany County, Ny, Bernd G. Neumann
Geology Theses and Dissertations
Plants growing in metalliferous soils may restrict metal uptake and transport depending on metal concentration, sediment characteristics, and plant species. As native plants are replaced by invasives, different patterns of metal cycling can occur, making continued study of this process important. Sediments and tissues of four aquatic plant species/genera: Phragmites australis (common reed); Iris versicolor (blueflag iris); Typha latifolia (broadleaf cattail); and genera Cyperus sp. (sedge) from three urban and two rural sites in Albany County, NY were analyzed for total mercury (HgT) by cold vapor atomic absorption spectroscopy. Sediments were also measured for organic carbon (OC) by …
Geochemical Fingerprinting Of Volcanic Airfall Deposits: A Tool In Stratigraphic Correlation, Soumava Adhya
Geochemical Fingerprinting Of Volcanic Airfall Deposits: A Tool In Stratigraphic Correlation, Soumava Adhya
Geology Theses and Dissertations
Chemical fingerprints of volcanic airfall deposits obtained from high-precision electron microprobe analysis of glass and phenocrysts phases provide geochemical correlations with temporal precision unattainable by other methods. In this research electron microprobe analysis (EMA) techniques, to fingerprint chemically and correlate fresh and altered volcanic airfall deposits, have been utilized to test the value of this tool for future research on stratigraphic correlation. The following samples were chosen from within a variety of sedimentary rocks widely separated spatially and temporally: (1) ∼450 Ma old upper Middle Ordovician K-bentonites (altered volcanic airfall deposits) collected from eastern United States. (2) Relatively fresh Pleistocene …
The Effect Of Chloride Ion On Heavy Metal Partitioning And Transport In An Urban Watershed: Patroon Creek, Albany, Ny, Charles Begeal
The Effect Of Chloride Ion On Heavy Metal Partitioning And Transport In An Urban Watershed: Patroon Creek, Albany, Ny, Charles Begeal
Geology Theses and Dissertations
Road deicing salt use in the United States has increased extensively over the last 60 years with urbanization and a need to keep roads safe during winter months. This increase has caused an overall increase in the base concentration of Cl- in streams near roads that receive deicing salts. Many of these streams are in the Northeast United States where extensive industrialization has led to the pollution of soils, sediments, and surface waters by heavy metals. This study addresses the effect that chloride concentration has on fluvial transport and partitioning of heavy metals between the dissolved and suspended phases in …
Extension And Exhumation Of The Hellenic Forearc And Radiation Damage In Zircon, Antonios E. Marsellos
Extension And Exhumation Of The Hellenic Forearc And Radiation Damage In Zircon, Antonios E. Marsellos
Geology Theses and Dissertations
Mapping and new structural observations on Kythera demonstrate the presence of a major detachment fault, which borders the domed structure of a metamorphic core complex. A three stage extensional context accompanied the exhumation of HP-rocks in Kythera. Early ductile structures near the mapped detachment fault indicate its initiation under NE-trending extension. Later ductile, ductile-brittle and some brittle structures, in the metamorphic unit near the detachment, indicate a significant NW-SE extension along-the-arc. The youngest brittle structures indicate return to NE-SW extension. Thermochronological and structural data show the intensive extension along-the-arc in the Kythera area fades out in both directions along the …
Outcrop Analog For Lower Paleozoic Hydrothermal Dolomite Reservoirs, Mohawk Valley, Ny, Brian E. Slater
Outcrop Analog For Lower Paleozoic Hydrothermal Dolomite Reservoirs, Mohawk Valley, Ny, Brian E. Slater
Geology Theses and Dissertations
Geochemical analysis and field relations of linear dolomite bodies occurring in outcrop in the Mohawk Valley of New York suggest that they have undergone significant fault-related hydrothermal alteration. The dolomite occurs in the Lower Ordovician Tribes Hill Formation, which is regionally an early Ordovician shaley limestone with patchy dolomitization. The outcrop has an en echelon fault, fracture, and fold pattern. A 3D ground penetrating radar survey of the quarry floor has helped to map out faults, fractures, anticlines, synclines and the extent of dolomitization. Most of the dolomitization occurs in fault-bounded synclines or “sags” flanked by anticlines. The dolomite structures …
Interdecadal-Decadal Climate Variability From Multi-Coral Oxygen Isotope Records In The South Pacific Convergence Zone Region Since 1650ad, Peipei Zhang
Geology Theses and Dissertations
Annual average oxygen isotope (δ18O) time series from five coral cores collected from Fiji and Tonga are used to construct a Fiji-Tonga Interdecadal-Decadal Pacific Oscillation (F-TIDPO) index of low frequency (>9yr and <55yr) climate variability in this area back to 1650 A.D. Presently, both Fiji and Tonga are located in the South Pacific Convergence Zone (SPCZ) salinity front region where the Interdecadal Pacific Oscillation (IPO) variation is most pronounced. We first demonstrate the consistency between this F-T IDPO index and a MSL pressure-based SPCZ Position Index (SPI) (1891-2000), thus verifying the ability of coral δ18O to record past interdecadal-decadal climatic variations in this region back to 1891. The F-T IDPO index is then shown to be synchronous with the IPO index (1856-2000), suggesting that this coral-based index effectively represents the interdecadal-decadal scale climate variance back to 1650. The consistently anti-phase spectrums of the F-T five-coral composite and the interdecadal-decadal components in equatorial Pacific coral δ18O series from Maiana [Urban et al., 2000] and Palmyra [Cobb et al., 2001] suggest that the simultaneous eastern expansion (western contraction) of the eastern salinity front of Western Pacific Warm Pool (WPWP) occurs at the same time as the northeast (southwest) movement of the SPCZ during a positive IPO (negative IPO) phase.
Late Structures And Strain History Accompanying Fluid Flows In The Western Taconic Orogen Of The New York-Vermont Appalachians, And, Structural Geology And Tectonic Evolution Of The Namche Barwa Region, Tibet, Chul Lim
Geology Theses and Dissertations
Parts of two separate collisional orogens are investigated in this study. One is the Middle-Late Ordovician Taconic orogen in eastern New York and western Vermont, and the other is the active Himalayan orogen of southeastern Tibet. Part I through III deal with a strain history and associated fluid properties during the late Taconic event in the western margin of the orogen and adjacent foreland. Senses of slip along slickensided quartz-calcite veins in the melange belt and their field relationships suggest an extension event following the late Taconic thrusting (Part I). In Part II, oxygen isotope analysis of veins and host …
Evaluating The Deep-Sea Coral Acanella From Hawaii As A Paleoceanographic Archive, Geraldine Hourigan Lantier
Evaluating The Deep-Sea Coral Acanella From Hawaii As A Paleoceanographic Archive, Geraldine Hourigan Lantier
Geology Theses and Dissertations
Deep-sea corals have emerged as potential proxies of changing paleoceanographic properties. The utility of deep-sea corals for the purpose of interpreting paleoclimatic reconstructions is still in the discovery phase. However, long life spans, a relatively stable habitat, and unique growth geometry provide support to the growing body of research that has identified deep-sea corals as indicators of past climate and ocean properties. Two colonies of Acanella were collected from the permanent thermocline at depths between 414 and 437 m in the Makapuu Coral Bed, Oahu, HI in 1997 by submersible. Here I present results from a pilot study of the …
Thermochronological Evidence For Neogene Incision Of The Rio Pativilca Canyon, Northern Peru, Matthew James Montario
Thermochronological Evidence For Neogene Incision Of The Rio Pativilca Canyon, Northern Peru, Matthew James Montario
Geology Theses and Dissertations
The Peruvian Andes have attained modern elevations of ~4000 m. Many peaks along the drainage divide are in excess of 5500 m with ~2-3 km of vertical relief, and canyons cut into the western edge have up to 3.5 km relief. The Rio Pativilica Canyon is cut into a folded Mesozoic marine sequence intruded by granitic rocks of the Coastal Batholith, which are overlain by Tertiary volcanics: this canyon has relief in excess of ~3 km. Based on geomorphological evidence, two episodes of valley incision cut the Puna erosional surface: 1) The Vallé stage, which is characterized by broad valleys …
The Effects Of Land Use Changes On Soil Carbon In The Russian Steppe, Andrew M. Ratigliano
The Effects Of Land Use Changes On Soil Carbon In The Russian Steppe, Andrew M. Ratigliano
Geology Theses and Dissertations
Increasing atmospheric CO2 levels within the past few centuries have led to many studies about the global carbon cycle. An important aspect in balancing the modern global carbon budget revolves around a missing sink of carbon. It is thought that the carbon accumulation in soil may be a significant component in this loss. As changes in land use under natural conditions have increased over the years, it is not well understood how these changes may affect the soil carbon. A useful technique in determining these changes are with the use of archived samples. Within a Russian steppe preserve that has …
Thermochronology And Provenance Of The Yakutat Terrane, Southern Alaska Based On Fission-Track And U/Pb Analysis Of Detrital Zircon, Stephanie Ellen Perry
Thermochronology And Provenance Of The Yakutat Terrane, Southern Alaska Based On Fission-Track And U/Pb Analysis Of Detrital Zircon, Stephanie Ellen Perry
Geology Theses and Dissertations
Northward transport of the Yakutat terrane along the Transition and Queen Charlotte-Fairweather transform faults led to Neogene collision of the Yakutat terrane with the southern continental Alaska margin. Northward translation resulted in a stratigraphy that records the erosion of thermotectonic terranes along its path. The strata of the Yakutat terrane includes the Lower Oligocene to Lower Eocene Kulthieth Formation, the Upper Eocene to Lower Miocene Poul Creek Formation and the Miocene-Pleistocene Yakataga Formation. Detrital zircon fission-track (DZFT) ages from stratigraphically coordinated samples collected in the Northern Robinson Mountains yield provenance information of the units that can shed light on their …
Assessing The Paleoceanographic Potential Of The Coral Montipora Venosa At Fanning Atoll, Central Equatorial Pacific, Alexa Stolorow
Assessing The Paleoceanographic Potential Of The Coral Montipora Venosa At Fanning Atoll, Central Equatorial Pacific, Alexa Stolorow
Geology Theses and Dissertations
As interest in global climate change increases, so does the need for better and more extensive climate proxies. The central equatorial Pacific has been established as the region with the largest ENSO-related sea surface temperature (SST) and precipitation (PPT) anomalies, which are known to impact global interannual climate variability. To date, the coral genus Porites has been most commonly utilized for coral-based paleo-reconstructions of ENSO and lower frequency phenomena. However, due to questions of biological artifacts in coral, to more fully understand coral-based reconstruction, different coral genera need to be analyzed.
In this study, oxygen (δ18O) and carbon (δ13C) isotopic …
Mapping Of A Detachment Fault In Kythera Island And Study Of The Related Structural Shear Sense Indicators, Antonios Marsellos
Mapping Of A Detachment Fault In Kythera Island And Study Of The Related Structural Shear Sense Indicators, Antonios Marsellos
Geology Theses and Dissertations
Kythera Island is located on the prominent submarine horst between Crete and the Peloponnese in the southwestern part of the Aegean. The structure of Kythera is characterized by a pile of tectonic slices derived from different paleogeographic zones. The upper unmetamorphosed units comprise pelagic limestones and cherts of Pindos zone emplaced by thrusting in the Eocene on top of Tripolis zone neritic limestones. These units are separated from the lower metamorphosed unit of Phyllite-Quartzite (PQU) exposed in the northern part of Kythera by an extensional detachment fault of Late Miocene age. The lower tectonic unit of PQU was affected by …
Petrology, Petrogenesis, And Tectonic Setting Of Jurassic Rocks Of The Central Cascades, Washington, And Western Klamath Mountains, California-Oregon, James H. Macdonald Jr.
Petrology, Petrogenesis, And Tectonic Setting Of Jurassic Rocks Of The Central Cascades, Washington, And Western Klamath Mountains, California-Oregon, James H. Macdonald Jr.
Geology Theses and Dissertations
This dissertation consists of four independent, yet related projects: (1) the petrology, geochemistry, and original tectonic setting of the Galice Formation, Klamath Mountains, Oregon-California; (2) the geochemistry, tectonic setting, and possible regional correlations of the Iron Mountain and Esmeralda Peaks units of the Ingalls ophiolite complex, central Cascades, Washington; (3) the provenance and original tectonic setting of sedimentary serpentinites and ophiolite breccias within the sedimentary rocks of the Ingalls ophiolite complex; and (4) geology, tectonics, and possible regional correlations of pre-Cenozoic rocks, central Cascades, Washington. This research indicates that the Galice Formation represents continuous Late Jurassic deposition (Oxfordian-Kimmeridgian), within the …
Source Of Meta-Igneous Blocks And Structure Of The Colebrooke Schist In The Snowcamp Peak Area, Pickett Peak Terrane, Southwestern Oregon, Jennifer Katrib
Source Of Meta-Igneous Blocks And Structure Of The Colebrooke Schist In The Snowcamp Peak Area, Pickett Peak Terrane, Southwestern Oregon, Jennifer Katrib
Geology Theses and Dissertations
The Colebrooke Schist of the Pickett Peak terrane, southwestern Oregon, is the easternmost, structurally highest unit of the Late Mesozoic-Cenozoic Franciscan Accretionary Complex. The Colebrooke Schist consists of mostly transitional greenschist-blueschist-facies meta-sedimentary rocks with common blocks of meta-volcanics and serpentinites, rare talc-schists and meta-plutonic rocks. The Colebrooke Schist meta-volcanic blocks are greenstones, in many cases with visible relict pillow structures and relict igneous textures.
Fifteen meta-volcanic samples and one meta-plutonic sample were analyzed by XRF and ICP-MS and were plotted with analyses from Plake (1989) and Coleman (1972). The Colebrooke Schist meta-volcanic rocks plot in mid-ocean ridge basalt (MORB), island …
Convergent And Collisional Tectonics In Parts Of Oregon, Maine, And The Vermont- Quebec Border, Adam Schoonmaker
Convergent And Collisional Tectonics In Parts Of Oregon, Maine, And The Vermont- Quebec Border, Adam Schoonmaker
Geology Theses and Dissertations
Four problems of tectonic significance were addressed. The first is a study of the structural emplacement of the Snowcamp ophiolite over the Rogue-Chetco arc complex during the Nevadan Orogeny in southwestern Oregon. Similarities in age, pressure and temperature conditions during thrusting, metamorphic history, and kinematics indicate that thrusting there was correlative with the nearby Madstone Cabin thrust. This implies that the overlying ophiolitic rocks have undergone a similar history as the Josephine ophiolite and are not exotic to Jurassic North America. Two projects involve the geochemical and field relationships of rocks in north-central Maine, which are used to constrain the …
Complexity Of Devonian K-Bentonites In The Appalachian Foreland Basin: Geochemical And Physical Evidence Supporting Multi-Layered K-Bentonite Horizons, Lucas Benedict
Geology Theses and Dissertations
Detailed analysis of Lower to Middle Devonian K-bentonites in the Appalachian Basin reveals physical and geochemical characteristics within supposed single eruptive event deposits that indicate a more complex depositional history is recorded in many of these volcanic beds. Variations in bedding showing multiple coarse and fine-grained layers within a K-bentonite layer can be seen in some Devonian K-bentonite beds. Microscopic irregularities show variations in the orientation of volcanic grains, and subtle phenocryst layers within a K-bentonite suggest changes in depositional environment where changing water and wave regimes rework and redeposit material on the sea floor. The presence of fossil layers …
Road Salt Application And Its Effects On Sodium And Chloride Ion Concentrations In An Urban Stream Patroon Creek, Albany, Ny, Elizabeth K. Erickson
Road Salt Application And Its Effects On Sodium And Chloride Ion Concentrations In An Urban Stream Patroon Creek, Albany, Ny, Elizabeth K. Erickson
Geology Theses and Dissertations
The application of road salt in an urban watershed leads to increased sodium and chloride concentrations in surface water and groundwater, which can adversely affect aquatic ecosystems, and may have consequences for soil cation exchange. This study focuses on the spatial and temporal variations in sodium and chloride concentrations in Patroon Creek, Albany County, New York, a tributary of the Hudson River. For two years, weekly surface water samples were gathered from 7 sites along Patroon Creek for major ion concentrations as measured by ion chromatography. Additionally, a USGS gage on Patroon Creek measures specific conductivity, water temperature, stage, and …
Stable Isotopic And Trace Metal Analyses Of Two Porites Lobata Colonies - Oahu, Hawaii: Implications For Past Seasonal Variation And Sea Surface Temperatures And Anthropogenic Effects On The Reef Environment, Jonathan Macdonald
Geology Theses and Dissertations
Corals from the western and equatorial Pacific Ocean have been extensively studied for the purposes of generating paleoclimate reconstructions spanning the last several hundred years. However, in the central subtropical North Pacific, there are currently few published coral records extending beyond 10 to 20 years. The hermatypic coral species Porites lobata and Porites lutea have proven to be useful indicators of paleoclimate and past sea surface conditions at other locations. Here I have analyzed two Porites lobata coral cores collected from colonies from opposite sides of Oahu, Hawaii to assess their utility for developing multi-decadal length climatic reconstructions in this …
Structural Analysis Of The Gonic Formation In Berwick, Maine, Joseph F. Renda
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 …
Geological Mapping And Crustal Shortening Of Central Tibet, Youshe Li
Geological Mapping And Crustal Shortening Of Central Tibet, Youshe Li
Geology Theses and Dissertations
Three geological maps in scale of 1:250,000 along the INDEPTH 3 survey line were made according to our field investigations in 1998 and 1999, extrapolated using TM image interpretation, combined with results from other previous work. This dissertation summarizes relevant geological information with references, including stratigraphy and fossil ages mainly from Chinese literature and discusses structure and shortening amount and the constraints on the ages. The Baingoin sheet of the geological map covers an area from N31° to N32°30', from E88°30' to E90°30'. The detailed structural and stratigraphic cross sections indicate about 50% shortening of the early-mid Jurassic, about 30% …
Assessing The Paleoclimatic Utility Of The Indo-Pacific Coral Genus Diploastrea In A 225-Year Oxygen Isotope Record From Fiji, Stefan Bagnato
Assessing The Paleoclimatic Utility Of The Indo-Pacific Coral Genus Diploastrea In A 225-Year Oxygen Isotope Record From Fiji, Stefan Bagnato
Geology Theses and Dissertations
In the Western Pacific there remains, both spatially and temporally, a sparse record of surface ocean conditions and very few long paleoclimate records able to extend our understanding of this important region. The coral genus Porites is the common coral currently used for Pacific paleoclimate studies and has proven to be very useful. The massive coral Diploastrea, due to its slow growth rate and dense structure, may preserve temporally longer geochemical proxy records than Porites colonies of the same length. Its long lifespan and fossil history give this genus great potential; however no assessment has been made of the paleoclimatic …
Sedimentology, Petrography, And Tectonic Significance Of Cretaceous To Lower Tertiary Deposits In The Tingri -Gyangtse Area, Southern Tibet, Bin Zhu
Geology Theses and Dissertations
Cretaceous and Lower Tertiary sedimentary rocks are well exposed in the Tingri-Gyangtse area, tectonically belonging to the central Tibetan Himalayas, to the south of the Indus-Yarlung-Zangbo suture. The Cretaceous Tianba flysch in the Tianba-Jiabula region is correlative with the Giumal Group sandstone in Zanskar, northwestern Himalayas. There are significant amounts of chrome-rich spinels in turbiditic sandstones from the upper part of Tianba Flysch, which might suggest ophiolite derivation and a Cretaceous ophiolite obduction event on the northern Indian continental margin in southern Tibet. However the compositional range of these detrital spinels closely matches that of spinels from intra-plate basalts. About …
Late Holocene Hydrologic And Climatic Variability In The Walker Lake Basin, Nevada And California, Fasong Yuan
Late Holocene Hydrologic And Climatic Variability In The Walker Lake Basin, Nevada And California, Fasong Yuan
Geology Theses and Dissertations
Oxygen and carbon isotopic measurements of the total inorganic carbon (TIC) fraction of sediments from Walker Lake (Nevada, USA) were completed at a decadal-scale resolution spanning the last ∼3000 years. On the basis of radiocarbon dating of the total organic fraction of cored sediments, the late Holocene isotope record recorded a relatively dry climate in Period LH-1 (1000 BC to AD 800), a relatively wet climate punctuated by a few severe droughts in Period LH-2 (AD 800 to 1900), and an anthropogenical perturbation era (L14-h: 1900–2000). Relative high accumulation rates in Period LH-2 (AD 800 to 1900) provided detailed information …
Field Relations, Structural Geology, And Geochemistry Of The Jonestown Volcanic Field, Lebanon County, Southeastern Pennsylvania, Tristan J. Ashcroft
Field Relations, Structural Geology, And Geochemistry Of The Jonestown Volcanic Field, Lebanon County, Southeastern Pennsylvania, Tristan J. Ashcroft
Geology Theses and Dissertations
The Jonestown Volcanic Field is a five kilometer by fifteen kilometer area of volcanic and hypabyssal rocks, basalt and diabase, located in southeastern Pennsylvania. These igneous rocks presently occur within an allochthonous belt of Ordovician deep water sedimentary rocks and Taconic flysch rocks known collectively as the Hamburg Klippe. Detailed field mapping during this project has revealed that the contacts between the igneous rocks and the flysch are not conformable. The volcanic rocks are associated with the Ordovician limestone that is adjacent to these volcanics. This limestone also is not conformable to the Hamburg Klippe sediments, rather it shares outcrop …