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GRK 1364:  Shaping the Earth's Surface in a Variable Environment: Interactions between Tectonics, Climate and Biosphere in the African-Asian Monsoonal Region

Subject Area Geology and Palaeontology
Term from 2006 to 2015
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 19943600
 
Final Report Year 2017

Final Report Abstract

The RTG GRK1364 was conducted by the University of Potsdam (UP), the Helmholtz Centre Potsdam - German Research Centre for Geosciences (GFZ), the Potsdam Institute for Climate Impact Research (PIK), and the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). Between 2006 and 2015, a total of 42 dissertation projects was realized. 33 PhD students finished with a degree. Five more did submit their theses. 31 PhD projects were originally funded, but 11 additional projects were associated and funded by independent DFG, BMBF, AWI, PIK, and UP grants. A total of 5 postdoctoral scholars was affiliated with the RTG. The Cenozoic history of the East African Rift and the Himalayan collision zone reflects the rich interactions between tectonics, climate, and the biosphere. Despite geologic and geodynamic differences, both environments are located in the realm of the Indian-African Monsoon and provide the possibility to analyze tectonic and climatic forcing mechanisms of surface processes, climate, environmental change, and biotic evolution on different timescales, ranging from decades to millions of years. Both regions are tectonically active, which has caused the diversion of atmospheric moisture transport, changes in rainfall location and amount, and environmental change. These effects of climate change and variability are superposed on the long-term tectonic processes associated with the mantle-driven regional uplift of the East African Plateau at about 17 Ma and the formation of the Himalayan orogenic wedge by sustained shortening until the present day. Both areas now constitute efficient orographic barriers for monsoonal precipitation, with pronounced rainfall gradients and accompanying differences in the density of vegetation and surface processes. The combination of tectonically controlled topography and climate has resulted in the formation of humid, high-elevation areas and semiarid lowlands between the rift shoulders and escarpments, and the foreland and interior parts of the Himalaya, respectively. Our research also shows that there appears to be a feedback between climatically controlled surface processes and tectonics: with out-of-sequence thrusting and tectonic reorganization triggered by variations in sedimentary loading in the toe area of the Himalayan orogenic wedge. Despite these observations of possibly climate-driven tectonic processes our new thermochronologic data and 10Be basin-wide erosion rates document that long-term exhumation is detached from erosion rates at shorter timescales and that high erosion rates may not always coincide with focused rainfall, but are rather influenced by fault activity over structural ramps. However, our studies of present-day and past environmental conditions also reveal the pivotal role of climate change and climate variability on the surface-process regime on shorter timescales. For example, climate-vegetation response model simulations, time series analysis of rainfall, and the application of atmospheric-moisture transport models helped identify and quantify the impact of the El Niño Southern Oscillation to East African Indian Monsoon rainfall variability, and revealed the role of teleconnections between the rainfall regimes in East Africa and the Indian subcontinent. In this context our studies clearly document the far-reaching impact of climate variability and associated lag times in hydrologic and sedimentary processes that repeatedly caused episodes of high sediment production during the onset of humid conditions when vegetation covers were thin. Conversely, a stabilization of the landscape with a denser vegetative cover and low erosion rates followed when the changeover to new environmental conditions was sustained over longer periods. By analogy, these areas may have been similar to conditions that characterize the present-day threshold regions between dry and humid areas whose erosion-rate measurements co-vary with vegetation density. In summary, the impact of the RTG for the UP and its extramural partners was profound. Not only new talented researchers were trained and scientific prestige was gained through first-tier publications and conference contributions, but new research alliances were forged and new forms of across-disciplinary training measures were established.

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