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Full-Text Articles in Physical Sciences and Mathematics
Crustal Evolution Of The New England Appalachians: The Rise And Fall Of A Long-Lived Orogenic Plateau, Ian Hillenbrand
Crustal Evolution Of The New England Appalachians: The Rise And Fall Of A Long-Lived Orogenic Plateau, Ian Hillenbrand
Masters Theses
The rise and demise of mountain belts, caused by growth, modification, or removal of the continental lithosphere are fundamental processes that influence almost all Earth systems. Understanding the nature, timing, and significance of active processes in the creation and evolution of modern mountain belts is challenged by a lack of middle crustal and lower crustal exposures. Analogues can be found in ancient orogens, whose deeply eroded roots offer a window into deeper processes, yet this record is complicated by overprinting events and complex deformational histories. Research presented herein constrains the tectonic history of multistage Appalachian Orogen, type locality of the …
Sedimentology, Sequence Stratigraphy, And High-Precision U-Pb Age Constraints On The Late Paleozoic Ansilta Formation, Calingasta-Uspallata Basin, Nw Argentina, John Ethan Malone
Sedimentology, Sequence Stratigraphy, And High-Precision U-Pb Age Constraints On The Late Paleozoic Ansilta Formation, Calingasta-Uspallata Basin, Nw Argentina, John Ethan Malone
Theses and Dissertations
The Ansilta Formation, located several kilometers east of the Astronomical Observatory El Leoncito near Barreal, San Juan Province, Argentina was deposited during the late Mississippian to early Pennsylvanian. This succession includes glacimarine, nearshore, and fluvial systems deposited at the mid-Carboniferous portion of the late Paleozoic ice age within the Calingasta—Uspallata Basin on the western margin of the Protoprecordillera. The lower member of the Ansilta Formation is equivalent to the nearby Leoncito, Majaditas, and Hoyada Verde formations, and is composed of diamictite, conglomerates, sandstones, pebbly mudstones, and laminated mudstone. Glacial environments are unique in that facies changes occur as a result …
Evidence For Polyphase Deformation In The Shear Zones Bounding The Chester And Athens Domes, Southeastern Vermont, From 40ar/39ar Geochronology, Kristin Schnalzer
Evidence For Polyphase Deformation In The Shear Zones Bounding The Chester And Athens Domes, Southeastern Vermont, From 40ar/39ar Geochronology, Kristin Schnalzer
Graduate College Dissertations and Theses
The Chester and Athens Domes are a composite mantled gneiss dome in southeast Vermont. While debate persists regarding the mechanisms of dome formation, most workers consider the domes to have formed during the Acadian Orogeny. This study integrates the results of 40Ar/39Ar step-heating of single mineral grains, or small multigrain aliquots, with data from microstructural analyses from samples collected in multiple transects across the dome-bounding shear zone(s) in order to understand the relationship between metamorphism and deformation. Results from the sheared units along the north and south transects are presented from west to east. In the north, hornblende from the …
Timing And Conditions Of Metamorphism In The Cascades Crystalline Core From Garnet Lu-Hf And Sm-Nd Geochronology, Peter Baker
Timing And Conditions Of Metamorphism In The Cascades Crystalline Core From Garnet Lu-Hf And Sm-Nd Geochronology, Peter Baker
WWU Graduate School Collection
The Chiwaukum Schist and Tonga Formation of Cascades Crystalline Core experienced three distinct metamorphic events: (M1) an early metamorphism that predates regional pluton emplacement, (M2) low-pressure contact metamorphism in the aureoles of the Mount Stuart batholith and Beckler Peak pluton, and (M3) regional Barrovian metamorphism. The timing of these distinct metamorphic events is critical to testing models for the tectonic evolution of the region and mechanisms that lead to burial of rocks within the orogen. I present new garnet Lu-Hf and Sm-Nd isochrons, average pressure and temperature calculations, and pseudosection modeling from the Chiwaukum Schist and Tonga Formation in order …