HEMIARID BASIN RESPONSES TO ABRUPT CLIMATIC CHANGE: PALEOLAKES OF THE TRANS-PECOS CLOSED BASIN |
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| Authors: | David E Wilkins |
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| Institution: | Department of Geography , University of Utah , 260 S. Central Campus Drive Rm. 270 Salt Lake City, Utah 84112–9155 david.wilkins@geog.utah.edu |
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| Abstract: | Western North American hemiarid basins situated along a climate boundary zone, or threshold, that separates regions of different climate regimes exhibit greater variability to changes in hydroclimatic variables. The Trans-Pecos Closed Basin study examines how global paleoclimatic factors and intrinsic geographic controls act in determining the threshold between states of hydroclimatic equilibria. Geomorphic, radiocarbon, and limnetic evidence identifies four major highstands for late Pleistocene Lake King during the Last Glacial Maximum (LGM). Patterns in the resulting model limnograph for Lake King suggest that runoff contributions from basin catchments to the inundated area were limited by precipitation rather than evaporation. Timing of the onset of lacustrine transgressive events corresponds with the later stages of cooling events recorded in the Greenland ice and North Atlantic deep-sea sedimentary record. Correlation of Trans-Pecos lacustrine environments with North Atlantic cooling implies that full pluvial conditions in the basin were limited to those periods when those cooling events resulted in extreme equatorward shifts of the LGM subpolar winter storm tracks, providing a moisture source to the basin. By comparing timing, intensity, and direction of climate change over a widely spaced array of hemiarid basins, the global implications of climatic events are better understood. Key words: Last Glacial Maximum, paleolakes, Pleistocene, Trans-Pecos Closed Basin, New Mexico, Texas.] |
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