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Full-Text Articles in Physical Sciences and Mathematics
Rapid Middle To Late Miocene Slip Along The Zanskar Normal Fault, Greater Himalayan Range, Nw, India: Constraints From Low-Temperature Thermochronometry, Brett L. Shurtleff
Rapid Middle To Late Miocene Slip Along The Zanskar Normal Fault, Greater Himalayan Range, Nw, India: Constraints From Low-Temperature Thermochronometry, Brett L. Shurtleff
All Master's Theses
The Zanskar normal fault (ZF) is a NW-striking, moderately NE-dipping, normal fault that bounds the northern flank of the Greater Himalaya Range, NW India. The ZF is the far west continuation of the South Tibetan Detachment System (STDS), a major arc-parallel normal sense shear zone that spans the length of the Himalayan orogen. Detailed new zircon and apatite (U-Th)/He (ZHe and AHe) and apatite fission-track (AFT) thermochronometric data from high-grade (amphibolite-migmatite) Greater Himalayan Sequence (GHS) metamorphic rocks, exposed in the footwall immediately adjacent to the ZF, provide constraints on the middle Miocene to present exhumation history of the footwall. The …
Clockwise Rotation Of The Brahmaputra Valley Relative To India: Tectonic Convergence In The Eastern Himalaya, Naga Hills, And Shillong Plateau, Philippe Vernant, R. Bilham, Walter Szeliga, D. Drupka, S. Kalita, A. K. Bhattacharyya, V. K. Gaur
Clockwise Rotation Of The Brahmaputra Valley Relative To India: Tectonic Convergence In The Eastern Himalaya, Naga Hills, And Shillong Plateau, Philippe Vernant, R. Bilham, Walter Szeliga, D. Drupka, S. Kalita, A. K. Bhattacharyya, V. K. Gaur
All Faculty Scholarship for the College of the Sciences
GPS data reveal that the Brahmaputra Valley has broken from the Indian Plate and rotates clockwise relative to India about a point a few hundred kilometers west of the Shillong Plateau. The GPS velocity vectors define two distinct blocks separated by the Kopili fault upon which 2–3 mm/yr of dextral slip is observed: the Shillong block between longitudes 89 and 93°E rotating clockwise at 1.15°/Myr and the Assam block from 93.5°E to 97°E rotating at ≈1.13°/Myr. These two blocks are more than 120 km wide in a north‐south sense, but they extend locally a similar distance beneath the Himalaya and …
Topographic Control Of Asynchronous Glacial Advances: A Case Study From Annapurna, Nepal, Beth Pratt-Sitaula, Douglas W. Burbank, Arjun M. Heimsath, Neil F. Humphrey, Michael Oskin, Jaakko Putkonen
Topographic Control Of Asynchronous Glacial Advances: A Case Study From Annapurna, Nepal, Beth Pratt-Sitaula, Douglas W. Burbank, Arjun M. Heimsath, Neil F. Humphrey, Michael Oskin, Jaakko Putkonen
All Faculty Scholarship for the College of the Sciences
Differences in the timing of glacial advances, which are commonly attributed to climatic changes, can be due to variations in valley topography. Cosmogenic 10Be dates from 24 glacial moraine boulders in 5 valleys define two age populations, late-glacial and early Holocene. Moraine ages correlate with paleoglacier valley hypsometries. Moraines in valleys with lower maximum altitudes date to the lateglacial, whereas those in valleys with higher maximum altitudes are early Holocene. Two valleys with similar equilibrium-line altitudes (ELAs), but contrasting ages, are < 5 km apart and share the same aspect, such that spatial differences in climate can be excluded. A glacial mass-balance cellular automata model of these two neighboring valleys predicts that change from a cooler-drier to warmer-wetter climate (as at the Holocene onset) would lead to the glacier in the higher altitude catchment advancing, while the lower one retreats or disappears, even though the ELA only shifted by ~120 m.
Recent Increase In Black Carbon Concentrations From A Mt. Everest Ice Core Spanning 1860-2000 Ad, Susan D. Kaspari, M. Schwikowski, M. Gysel, M. G. Flanner, S. Kang, S. Hou, P. A. Mayewski
Recent Increase In Black Carbon Concentrations From A Mt. Everest Ice Core Spanning 1860-2000 Ad, Susan D. Kaspari, M. Schwikowski, M. Gysel, M. G. Flanner, S. Kang, S. Hou, P. A. Mayewski
All Faculty Scholarship for the College of the Sciences
A Mt. Everest ice core spanning 1860–2000 AD and analyzed at high resolution for black carbon (BC) using a Single Particle Soot Photometer (SP2) demonstrates strong seasonality, with peak concentrations during the winter‐spring, and low concentrations during the summer monsoon season. BC concentrations from 1975–2000 relative to 1860–1975 have increased approximately threefold, indicating that BC from anthropogenic sources is being transported to high elevation regions of the Himalaya. The timing of the increase in BC is consistent with BC emission inventory data from South Asia and the Middle East, however since 1990 the ice core BC record does not indicate …
Middle Crustal Ductile Deformation Patterns In Southern Tibet: Insights From Vorticity Studies In Mabja Dome, Jackie Langille
Middle Crustal Ductile Deformation Patterns In Southern Tibet: Insights From Vorticity Studies In Mabja Dome, Jackie Langille
All Master's Theses
Mabja Dome, southern Tibet, exposes mid-crustal rocks proposed to have originated from a southward flowing mid-crustal channel. Kinematic, mean kinematic vorticity (Wm), and metamorphic petrography analyses on these mid-crustal rocks were performed to test this hypothesis. Kinematic indicators show a transition with structural depth from top-north and top-south shear to solely top-south shear. Along the northernmost transects, Wm in schists and orthogneisses range from 0.52–0.84 (63–36% pure shear). Wm for quartzites ranges from 0.9–0.99 (27–1% pure shear). Deformation temperatures increase from ~450 °C in the chloritoid-zone to ~700 °C in the sillimanite-zone and were recorded between ~35–16 Ma. These patterns …