HR: 0800h
AN: PP31B-1536    [Abstracts]
TI: A Record of Changes in the Indian Monsoon From ~29 ka to 11 ka Based on a Stalagmite from Socotra Island, Yemen
AU: * Shakun, J D
EM: jshakun@geo.umass.edu
AF: Department of Geosciences University of Massachusetts , Morrill Science Center 611 N. Pleasant St., Amherst, MA 01003 United States
AU: Burns, S J
PP31B-1536 AF: Department of Geosciences University of Massachusetts , Morrill Science Center 611 N. Pleasant St., Amherst, MA 01003 United States
AU: Fleitmann, D
PP31B-1536 AF: Institute of Geological Sciences, University of Bern, Bern, CH-3012 Switzerland
AU: Kramers, J
PP31B-1536 AF: Institute of Geological Sciences, University of Bern, Bern, CH-3012 Switzerland
AU: Matter, A
PP31B-1536 AF: Institute of Meteorology, University of Leipzig, Leipzig, D-04103 Germany
AU: Al-Subary, A
PP31B-1536 AF: Department of Geological Sciences, Sana'a University, Sana'a, 15201 Yemen
AB: Stalagmite M1-5 from Socotra Island, Yemen in the northwest Indian Ocean provides a robust, high-resolution paleoclimate record from 28.5-11.1 ka based on 681 stable isotope and 28 234U/ 230Th measurements. Variations in M1-5 oxygen isotope ratios are interpreted to be primarily driven by an amount effect and to principally reflect changes in the mean position and/or intensity of convection of the intertropical convergence zone. Migration of the ITCZ over the region is the island's source of precipitation. The M1-5 d18O time series is strongly correlated to the Greenland ice cores, similar to an earlier Socotra speleothem record from 53-40 ka (Burns et al., 2003), indicating a North Atlantic-Indian Ocean cold-dry/warm-wet teleconnection persisted through the end of the last glacial period. D/O events 1, 2, 3, Heinrich events 0 and 1, and the Holocene onset are well expressed in M1-5, and the Last Glacial Maximum occurs at ~23 ka, consistent with northern hemisphere ice volume and temperature forcing. M1-5 correlates well with Arabian Sea monsoon-driven productivity and denitrification records as well as the Hulu and Dongge Cave speleothem records from China over decadal to millennial timescales, indicating the entire East African-Asian monsoon system behaved as a cohesive unit during the last deglaciation. M1-5 is also highly coherent with records from the Cariaco Basin during the Bolling/Allerod period, and generally coherent over longer timescales as well, suggesting the intertropical convergence zone fluctuated in unison in the Indian and Atlantic Ocean basins. Significant antiphasing is seen between M1-5 and the Byrd ice core from Antarctica throughout the entire length of the speleothem record, implying the operation of the bipolar seesaw during this interval. In fact, M1-5 is more strongly anticorrelated with Antarctica than is Greenland, suggesting a potential bipolar seesaw mechanism (or feedback) other than the Atlantic thermohaline circulation, perhaps involving the Indian Ocean monsoon itself. Differences in the structure of the Bolling/Allerod in M1-5 and other tropical records from the B/A in polar ice cores suggests a complex but as yet poorly understood pattern of global climate. M1-5 isotopes are dramatically different from those in a coeval speleothem record from Socotra (Reale et al., 2003), highlighting the importance of sample selection and climate signal authentication in speleothem studies.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 9340 Indian Ocean
DE: 9604 Cenozoic
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005