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Full-Text Articles in Physical Sciences and Mathematics
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 …
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 …
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 …
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 …
The Use Of A Synthetic Binary Solid Solution To Model Igneous Textural Evolution, Elizabeth Scott
The Use Of A Synthetic Binary Solid Solution To Model Igneous Textural Evolution, Elizabeth Scott
Geology Theses and Dissertations
Crystallization experiments using a synthetic igneous analog have shown that grain boundary migration can take place in melt-present environments (Means and Park, 1994). In order to evaluate the importance of metamorphic processes during the textural evolution of a crystal mush, microstructural evidence is needed to link them with final igneous textures. In natural magmatic systems, plagioclase may provide a microstructural link; plagioclase solid solution enables the process of chemical zoning and preserves a record of crystal morphology (and chemistry) during growth. If metamorphic processes are common, they should affect the zoning patterns of plagioclase crystals.
A petrographic stage heater apparatus …
Identification Of Past Climate Variability Of The Eastern Pacific Ocean Using Both D13c And D18o Records In Corals From Clipperton Atoll (1994-1906), Lei Ren
Geology Theses and Dissertations
The ENSO (El Nino and the Southern Oscillation) is a fundamental ocean-atmosphere phenomenon that dominates interannual global climate variability. Reconstructing past ENSO events is therefore important for documenting and understanding the past behavior of the global climate system and enabling us to predict future climate change. However, the present understanding of ENSO events has been mainly based on the instrumental record of Pacific climate which provides detailed data only for the past few decades. Recent studies have shown that the stable isotope record in coral skeletons can be used as a valuable indicator of paleoclimatic changes in tropical regions, and …
Trace-Element Modelling Of Melting In Spinel Peridotites, Susanne Petra Vogel
Trace-Element Modelling Of Melting In Spinel Peridotites, Susanne Petra Vogel
Geology Theses and Dissertations
This study addresses three independent topics related to trace element modeling of spinel peridotites that are suggested by the pioneering work of Johnson et al. (1990) on abyssal harzburgites.
First, the fractional non-modal melting equation derived by Johnson and coworkers (1990) is algebraically modified to present a "one-element/two-phase" model. This model suggests a simple test for estimating mantle heterogeneity in the source rock of spinel lherzolites. This model is applied to data from the literature for samples from Dreiser Weiher, Germany; San Luis Potosi, Mexico; and Western Victoria, Australia.
Second, trace elements in clinopyroxenes of abyssal peridotites and continental spinel …
Mineral Paragenesis Of The Granulite Facies In The Lake George Area, New York, Boknam Ree
Mineral Paragenesis Of The Granulite Facies In The Lake George Area, New York, Boknam Ree
Geology Theses and Dissertations
The Lake George Area belongs to the southeastern part of the Adirondack Highlands. The rocks of this area show variations in mineral assemblages which are caused by differences in bulk chemical composition. This makes it unsuccessful to use a subdivision of the granulite facies which is suggested by de Waard (1965).
The CFM diagram (Abbott, 1982) is used to show the relationship between composition and paragenesis of the Lake George Area. In this study, a different result has been found in the order of partitioning of Fe between coexisting minerals, namely, garnet>hornblende>biotite>orthopyroxene>clinopyroxene. The hornblende granitic gneiss …
Identification Of Endmembers For Magma Mixing In Little Sitkin Volcano, Alaska, Douglas A. Wolf
Identification Of Endmembers For Magma Mixing In Little Sitkin Volcano, Alaska, Douglas A. Wolf
Geology Theses and Dissertations
Little Sitkin island is an Aleutian calc-alkalic volcanic center that has erupted a suite of lavas ranging from andesite through rhyodacite. Whole-rock chemistry of these lavas indicates contrasting evolutionary processes; major-oxide silica variation diagrams exhibit linear trends that are suggestive of magma-mixing while trace-element trends are largely controlled by accessory-phase fractionation.
Plagioclase, the dominant phenocryst phase in all lavas, commonly occurs in two distinct populations with markedly different compositions and textures. Both normal and reverse zonation is noted in the plagioclase and clinopyroxene of several samples. In addition, clinopyroxene is found as rims on orthopyroxene grains and as cores with …
Some Chemical And Mineralogical Aspects Of Plutonic Rocks From The North Arm Mountain Massif, Bay Of Islands Ophiolite, Newfoundland, Jerry W. Sullivan
Some Chemical And Mineralogical Aspects Of Plutonic Rocks From The North Arm Mountain Massif, Bay Of Islands Ophiolite, Newfoundland, Jerry W. Sullivan
Geology Theses and Dissertations
Whole-rock major and trace element compositions of one basalt, one diabase, and 21 rocks from the magmatic-plutonic units of the North Arm Mountain massif, Bay of Islands ophiolite, Newfoundland, were determined. Mineral compositions of a subset of the plutonic rocks were also determined.
The major and trace element compositions of the basalt and diabase are similar to abyssal tholeiites, and this is consistent with the REE data of Malpas (1978) and Suen, et. al. (1979) that suggest the lavas and dikes formed from a depleted or slightly enriched abyssal tholeiitic magma. The alkaline nature of the magma proposed by several …
Saratoga: The Bubbles Of Reputation And Their Implications For An Embryonic Rift System In The Upper Hudson River Valley, James R. Young
Saratoga: The Bubbles Of Reputation And Their Implications For An Embryonic Rift System In The Upper Hudson River Valley, James R. Young
Geology Theses and Dissertations
Carbonated, alkaline, saline waters occur over a wide area in the upper Hudson River Valley approaching 1,000 square miles. Through the sampling (spring and fall) of 39 locations, half of which were hitherto unsampled, the waters are shown to be a complexly mixed system with at least five major components.
They are:
1) a gaseous phase consisting primarily of CO2;
2) a fluid (containing the dissolved CO2) possibly analogous to a metamorphic brine whose major chemistry is HCO3>Na>Cl;
3) formational waters of variably low salinities which may be the end products of progressive dilution of Paleozoic connate brines …
Petrology Of The Oceanographer Fracture Zone (35ºn35ºw), Tsugio Shibata
Petrology Of The Oceanographer Fracture Zone (35ºn35ºw), Tsugio Shibata
Geology Theses and Dissertations
During a geological and geophysical survey of the Oceanographer Fracture Zone (35°N, 35°W), seventeen dredge hauls containing a variety of rocks were obtained. Petrographic study shows that these rock samples can be classified into six main rock types: fresh basalt, weathered basalt, metabasalt, gabbro, metagabbro, and serpentinite. Most of the dredge hauls were positioned on the steep, southern wall of the fracture zone, and an inference from the dredging results suggests that basalt is the most abundant rock type which outcrops at the junction between the rift valley and the fracture zone; however, as we move away from the junction, …
Petrology Of The Nemeiben Lake Ultramafic And Associated Nickel-Sulphide Deposits, Anantaramam Peddada
Petrology Of The Nemeiben Lake Ultramafic And Associated Nickel-Sulphide Deposits, Anantaramam Peddada
Geology Theses and Dissertations
The Nemeiben Lake ultramafic body is located in the center of Saskatchewan, Canada, within the Churchill Province of the Canadian Shield. The ultramafic rocks consist of serpentinites, partly serpentinized and uralitized pyroxenite, and unaltered pyroxenite. Associated sulphide mineralization is of disseminated, net texture, and fracture filling types. The ore minerals present are pyrrhotite, pentlandite, chalcopyrite, pyrite, marcasite, violarite, bravoite and native copper. The sulphides are considered to be initially of magmatic origin formed from a sulphide melt separated at a late stage during crystallization of the ultramafic rocks. Subsequent serpentinization has locally redistributed the ores.
Serpentinization in the Nemeiben Lake …