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Full-Text Articles in Physical Sciences and Mathematics
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 …
Stratigraphy And Structure At The Southern End Of Lake Champlain In Benson, Vermont, Jennifer L. Granducci
Stratigraphy And Structure At The Southern End Of Lake Champlain In Benson, Vermont, Jennifer L. Granducci
Geology Theses and Dissertations
Detailed mapping and structural investigations in an area bound to the west by the Grenvillian basement of the Adirondack Mountains and to the east by the allochthonous slates of the Taconic Mountains led to the distinction of a Western Undeformed Zone and an Eastern Deformed Zone. The former is composed of the gently east-dipping shelf sequence of upper Cambrian to lower Ordovician clastics and carbonates which unconformably overlie the Precambrian basement. The latter is characterized by lower to middle Ordovician carbonates, striking roughly north-south and dipping predominantly to the east, which are overlain by well-cleaved shales and slates. The stratigraphic …
Correlation Of The Tioga Bentonites Using Rhyolitic Melt Inclusions Found In Quartz Phenocrysts As Geochemical Fingerprints, John W. Waechter
Correlation Of The Tioga Bentonites Using Rhyolitic Melt Inclusions Found In Quartz Phenocrysts As Geochemical Fingerprints, John W. Waechter
Geology Theses and Dissertations
The Tioga bentonites were first noted by Fettke in 1931 from well cuttings in the Tioga gas fields of Tioga County, Pennsylvania. They have been used by many investigators (Oliver, 1954, 1956; Dennison, 1963; Dennison and Textoris, 1967, 1978; Epstein, 1986; Smith and Way, 1983; Way et al., 1986) as a time-plane to correlate stratigraphic units from eastern Pennsylvania to Illinois and from southern Ontario to Virginia. The Tioga bentonites are recognized as seven major volcanic ash layers labeled Tioga-A - Tioga-G as well as several minor layers labeled Tioga-A1 - Tioga-A3 (Way et al., 1986). They occur within the …
Stratigraphy And Structure Of The Ganson Hill Area: Northern Taconic Allochthon, Michelle Aparisi
Stratigraphy And Structure Of The Ganson Hill Area: Northern Taconic Allochthon, Michelle Aparisi
Geology Theses and Dissertations
The Ganson Hill study area is located in the Giddings Brook Slice of the Taconic Allochthon. It contains rocks of Cambrian(?), Cambrian and Ordovician age. The predominant rock type is slate with subordinate lithologies including quartzite, limestone, micrite, arenite and graywacke. The lithostratigraphy identified in the Ganson Hill area extends from the basal Bomoseen wacke to the Poultney slate. A more precisely defined lithostratigraphy is derived from the study area by the occurrence and recognition of the Middle Granville Slate Formation and the documentation of a second Cambrian black/green boundary. Previous workers have included this formation in different places, in …
Geological And Thermal Aspects Of The Southern San Joaquin Basin, California: Application Of The 40ar/39ar Stepwise Heating Technique To Detrital Microclines, Kenneth Bé
Geology Theses and Dissertations
The depositional history of the southernmost region of the trough-shaped San Joaquin Basin spans from Upper Eocene to Recent time. The stratigraphy reveals both a predominantly marine environment which persisted until the Upper Pliocene, as well as nonmarine environments along the basin's margins. Folds and faults within the basin have resulted directly from movements along the San Andreas fault. Although the exact time of origin of the Big Bend is unclear, this major feature in the San Andreas fault's geometry has played an important role in recent crustal tectonics of southern California. Significantly, the southern San Joaquin's depocenter has undergone …
Structure And Stratigraphy Of West Haven, Vermont, Christoph K. Steinhardt
Structure And Stratigraphy Of West Haven, Vermont, Christoph K. Steinhardt
Geology Theses and Dissertations
Mapping and structural investigations in an area bounded to to the west by by Grenvillian basement and to the east by allochthonous rocks emplaced during the medial Ordovician Taconic Orogeny led to division of the area into a Western Undeformed Zone and an Eastern Deformed Zone. The former consists of a thin, undeformed shelf sequence of upper Cambrian to lower Ordovician (Canadian) clastics and carbonates, which unconformably overlie Grenvillian basement and dip gently to the east.
The Eastern Deformed Zone consists of early to medial Ordovician carbonates folded about northnortheast trending axes with east to southeast dipping axial surfaces, overlain …
Geology Of The Western Boundary Of The Taconic Allochthon Near Troy And The Anastomosing Cleavage In The Taconic Melange, Zong-Guo Xia
Geology Of The Western Boundary Of The Taconic Allochthon Near Troy And The Anastomosing Cleavage In The Taconic Melange, Zong-Guo Xia
Geology Theses and Dissertations
The Taconic Allochthon is located in eastern New York, western Vermont, western Massachusetts, and western Connecticut and extends about 200 kilometers north-south and east-west for about 25 kilometers. It contains rocks of Late Proterozoic, Cambrian and Ordovician age. The rocks are predominantly slates with lesser amounts of arenites, wackes, limestone, chert, and conglomerates. All rocks have been subjected to chlorite or biotite grade metamorphism and at least two generations of deformation. The emplacement of the Taconic Allochthon onto the coeval shelf took place during the Middle Ordovician Taconic Orogeny.
The study area lies at the western margin of the Taconic …
Structure And Tectonics Of The Keban Metamorphics In The Northern Margin Of The Bitlis Suture Zone, Southeastern Turkey, Gültekin Savci
Structure And Tectonics Of The Keban Metamorphics In The Northern Margin Of The Bitlis Suture Zone, Southeastern Turkey, Gültekin Savci
Geology Theses and Dissertations
The study area near Keban consists of the allochthonous Keban division of the Keban-Malatya crystalline complex and the Yuksekova island-arc rocks of the Bitlis-Puturge Complex in the northern margin of the Bitlis Suture Zone. Detailed mapping shows that the Palaeozoic-Triassic Keban Metamorphics are composed of the following formations: (1) white, massive, karstic Kirklar Marble; (2) phyllitic psammite with calcschist interlayers Calik Formation; and (3) semi-crystallized gray Koyunatlayan Limestone. These formations define a tectonostratigraphy with the Kirklar Marble at the base and the Koyunatlayan Limestone at the top. The detailed lithological description of the Keban Metamorphic rock assemblages suggest that they …
Complex Structure And Stratigraphy Of Lower Slices Of The Taconic Allochthon Near Middle Granville, New York, David B. Rowley
Complex Structure And Stratigraphy Of Lower Slices Of The Taconic Allochthon Near Middle Granville, New York, David B. Rowley
Geology Theses and Dissertations
The Precambrian (?) to medial Ordovician rocks of the Taconic Allochthon are characterized by argillaceous and arenaceous sediments with lesser associated carbonates, carbonate breccias, and cherts of predominantly deep-water aspect. These allochthonous rocks tectonically overlie an autochthonous to parautochthonous coeval sequence of dominantly shallow marine clastics and carbonates of the Champlain and Vermont Valley sequences. Facies, thickness, sedimentologic, and paleontologic considerations suggest that these coeval sequences represent a carbonate shelf continental rise pair of the east-facing early Paleozoic Atlantic-type margin of North America. This margin formed by the opening of an ocean in latest Precambrian time. The stratigraphy of the …
Structural Geology Of The Fort Miller, Schuylerville And Portions Of The Schaghticoke 7½' Quadrangles, Eastern New York, And Its Implications In Taconic Geology; And Experimental And Theoretical Studies Of Solution Transfer In Deforming Heterogeneous Systems, William P. Bosworth
Geology Theses and Dissertations
Stratigraphies previously proposed for the Taconic sequence of southern Washington County, eastern New York, have incorrectly defined and positioned lower Cambrian black slate units. The proper sequence of Cambrian (?) through Cambrian lithologies is (terminology from Jacobi, 1977): Bomoseen green wacke, Truthville green slate, Browns Pond black slate, Mettawee purple and green slate, and West Castleton and Hatch Hill black slates. This and the entire Taconic sequence is conformable within the western Giddings Brook slice. The detailed lithostratigraphy reported by Jacobi (1977) and Rowley (1980) in northern Washington County can be followed at least some 45 kilometers to the south …
Paleoclimatic Implications Of Oxygen Isotope And Sedimentological Study Of Late Miocene And Early Pliocene Sediments From The South Atlantic, Western Indian Ocean, And The Gulf Of Aden, Kathryn M. Scanlon
Geology Theses and Dissertations
Previous work by many authors has implied that the Antarctic ice sheet underwent a major expansion in the latest Miocene. It was intended in the present study to use the oxygen isotope event, which could be expected to accompany this glacial expansion, as a stratigraphic marker to aid in the correlation of several DSDP Sites. Samples were taken at approximately 100,000 year intervals throughout the latest Miocene and early Pliocene sections at Sites 237 and 249 in the western Indian Ocean, Site 360 in the South Atlantic and Site 231 in the Gulf of Aden. Oxygen isotope analyses were done …
The Development Of Foliations In Low, Medium And High Grade Metamorphic Tectonites, William J. Gregg
The Development Of Foliations In Low, Medium And High Grade Metamorphic Tectonites, William J. Gregg
Geology Theses and Dissertations
Studies of foliation and associated microstructures are presented from a variety of rock types and localities in the metamorphic terrains of the northeastern United States.
At Islesboro, Maine cleavage is well developed in lower greenschist grade siltstones and interbedded pelites of lower Paleozoic age. Cleavage in the siltstone units consists of two types of discrete mica films: short film segments and lengthened mica film. Thick secondary mica-rich layers are also exhibited in some siltstones. The short film segments appear to be basic elements through which cleavage development progresses by a linkage process that is poorly understood. The linkage of these …
Geology Of The Badger Bay-Seal Bay Area, North-Central Newfoundland, K. Douglas Nelson
Geology Of The Badger Bay-Seal Bay Area, North-Central Newfoundland, K. Douglas Nelson
Geology Theses and Dissertations
Coastline in the Badger Bay-Seal Bay area of north-central Newfoundland exposes the thickest and least disrupted section of Ordovician rocks in Newfoundland's Central Volcanic Belt. The following conformable stratigraphic sequence is observed: 1) >5 km. of variegated mafic and silicic submarine volcanics and volcaniclastics of lower Ordovician age; 2) a thin (<.5 km.) sequence consisting of thin bedded red and green argillites, manganiferous cherts, bioturbated cherts and black sulferous graptolite-bearing argillites of Caradocian age; 3) >1.2 km. of quartz-rich sandstones of upper Ordovician age. Correlative sequences occur to the east in the Fortune Harbour Peninsula area and on New World Island. Together they record Early Ordovician island arc volcanism, Medial Ordovician cessation of volcanism and subsidence, and Medial through Late Ordovician uplift and …
Stratigraphy, Depositional Environment And Structure Of The Taconic Allochthon, Central Washington County, New York, Louise D. Jacobi
Stratigraphy, Depositional Environment And Structure Of The Taconic Allochthon, Central Washington County, New York, Louise D. Jacobi
Geology Theses and Dissertations
The Taconic Allochthon contains rocks of Cambrian (?), Cambrian and Ordovician age. It measures approximately 200 kilometers by 25 kilometers and is located in contiguous sections of New York, Vermont, Massachusetts, and Connecticut. The rocks are predominantly slates with lesser amounts of arenites, wackes, limestone, chert, and conglomerates. All have been subjected to chlorite or biotite grade metamorphism and two tectonic deformations. The study area in central Washington County, New York, contains most of the Taconic sequence, and because of both natural and man-made exposure it is more accessible than most other locations. A lithostratigraphic column has been identified which …
Structural Studies In The Northern Chester Dome Of East-Central Vermont, Bruce Wallace Nesbit
Structural Studies In The Northern Chester Dome Of East-Central Vermont, Bruce Wallace Nesbit
Geology Theses and Dissertations
Rocks in the Eastern Vermont Sequence are highly metamorphosed and are said to range in age from Precambrian to Siluro-Devonian. The sequence outcrops on Keyes Mountain, about 6km Northwest of Felchville, Vermont, and an area on this mountain about 2km square was mapped in great detail.
The dominant rock type found is quartzofeldspathic gneiss, but schistose gneiss, amphibolite, quartzite and schist also occur. Most of these rocks are layered but layering has been transposed in many places and much of it is probably secondary. Layering and schistosity both dip dominantly to the north at about 25º.
A number of mesoscopic …