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Full-Text Articles in Physical Sciences and Mathematics
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
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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
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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
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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 …