HR: 1340h
AN: PP33B-1577    [Abstracts]
TI: Geomorphic and sedimentary responses to strengthened early-Holocene monsoons: Evidence for contemporaneous 'events' in South Asia and Australia
AU: * Goodbred, S L
EM: steven.goodbred@vanderbilt.edu
AF: Vanderbilt University, Earth and Environmental Sciences VU Station B 351805, Nashville, TN 37235-1805 United States
AB: Monsoon strength is especially sensitive to regional insolation and thus generally varies with orbital cycles. However, the magnitude of this variability is affected by still poorly understood linkages with global boundary conditions (e.g., ice cover) and/or oceanographic feedbacks. Over the past 125,000 years, one of the most notable monsoon excursions was a dramatic strengthening during the early Holocene hypsithermal. In South Asia, the impact of this enhanced monsoon is recognized from alpine valley glaciers, bedrock valley alluviation, floodplain incision, and continental margin sedimentation, all indicating a system wide response to increased monsoon precipitation. No other similar geomorphic/sedimentologic episode has been recognized from the late Quaternary. Age control on these responses is not ideal, but encompass dates from 4-12 ka with most distributed 6-10 ka. More work is needed to constrain these ages, although they are clearly linked with the monsoon strengthening. Switching to the southern hemisphere, research in northeast Australia has documented very similar geomorphic/sedimentary behavior, such as floodplain incision and rapid continental margin sedimentation. The timing of these responses are effectively contemporaneous with those in South Asia, concentrating from 6-10 ka. Taken together, these findings support: 1) the occurrence of a brief (?) but dramatic strengthening of South Asian and Australian monsoons; 2) that this excursion was largely contemporaneous in both the northern and southern hemispheres; and 3) that erosional, transport, depositional systems responded acutely to these changes in climate.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1625 Geomorphology and weathering (0790, 1824, 1825, 1826, 1886)
DE: 1825 Geomorphology: fluvial (1625)
DE: 1861 Sedimentation (4863)
DE: 4914 Continental climate records
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005