HR: 1340h
AN: OS33A-0995 INVITED    [Abstracts]
TI: Climate and Tectonic Signals Preserved in the Indus Submarine Fan, Arabian Sea
AU: * Clift, P
EM: pclift@abdn.ac.uk
AF: University of Aberdeen, School of Geosciences, Aberdeen, AB24 3UE, United Kingdom
AU: Calves, G
EM: g.calves@abdn.ac.uk
AF: University of Aberdeen, School of Geosciences, Aberdeen, AB24 3UE, United Kingdom
AU: Giosan, L
EM: lgiosan@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Tabrez, A R
EM: ali_tabrez786@yahoo.com
AF: National Institute of Oceanography, ST-47-Block 1, Clifton, Karachi, 75600, Pakistan
AU: Inam, A
EM: niopk@cubexs.net.pk
AF: National Institute of Oceanography, ST-47-Block 1, Clifton, Karachi, 75600, Pakistan
AU: Rabbani, M M
EM: niopk@cubexs.net.pk
AF: National Institute of Oceanography, ST-47-Block 1, Clifton, Karachi, 75600, Pakistan
AB: Sediments preserved in the submarine fan fed by the Indus River record the interactions between climate and tectonics in the western Himalaya since the start of India-Asia collision, especially exhumation of the Greater Himalaya and intensification of the Asian monsoon. Seismic stratigraphic mapping has revealed peaks in sedimentation rates during the Middle Miocene and Plio-Pleistocene. These periods correlate with times of rapid exhumation in the Greater Himalaya and with intense chemical weathering driven by a strong monsoon initiating around 22 Ma. Correlation of these maxima with similar events lasting >1 m.y. in East Asia suggests a dominant climatic/monsoonal control to erosion and sediment flux to the deep sea. Coring of Holocene sediment from the Indus delta allows us to assess climatic controls on erosion over millennial timescales. Total sediment flux increased sharply in the Early Holocene coincident with a strengthening monsoon allowing the coast to prograde seawards despite rising sealevels. Bulk sediment Nd isotope analysis reveals less erosion of the Karakoram and more sediment flux from the Himalaya during the early and middle Holocene. Radiometric Ar-Ar dating of muscovite and U-Pb dating of zircon sand grains indicates that the Lesser Himalaya eroded relatively more strongly than the Greater Himalaya as the summer monsoon intensified after 14 ka. This variation is preserved with no apparent lag in sediments from the delta, but not in the deep Arabian Sea, due to sediment buffering on the continental shelf and the failure of the Indus to reconnect to its submarine fan since ca. 11 ka.
DE: 1051 Sedimentary geochemistry
DE: 1815 Erosion
DE: 1862 Sediment transport (4558)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 4914 Continental climate records
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting