A high-resolution, absolute-dated deglacial speleothem record of Indian Ocean climate from Socotra Island, Yemen

摘要

Stalagmite M1-5 from Socotra Island, Yemen in the northwest Indian Ocean provides a robust, high-resolution paleoclimate record from similar to 27.4-11.1 ka based on 717 stable isotope and 28 Th-230 measurements. Variations in M1-5 oxygen isotope ratios (delta O-18) are interpreted to be primarily driven by an amount effect related to changes in the mean position and/or intensity of convection of the intertropical convergence zone, the island's only source of precipitation. The M 1-5 delta O-18 time series is strongly correlated to the Greenland ice cores, similar to an older Socotra speleothem deposited from 53-40 ka [S.J. Bums, D. Fleitmann, A. Matter, J. Kramers, A. Al-Subbary, Indian Ocean climate and an absolute chronology over Dansgaard/Oeschger events 9 to 13, Science 301 (2003) 1365-1367], indicating that a North Atlantic-Indian Ocean cold-dry/warm-wet teleconnection persisted through the end of the last glacial period. Peak aridification occurred at similar to 23 ka and a gradual increase in moisture thereafter was interrupted by an abrupt drying event at similar to 16.4 ka, perhaps related to Heinrich event 1. Indian Ocean rainfall increased dramatically during the Bolling period and then decreased continuously and gradually through the Allerod and Younger Dryas. The Holocene began abruptly with increased precipitation at 11.4 ka and was followed by a major but short-lived drying during the Preboreal Oscillation at similar to 11.2 ka. M1-5 is highly correlated to the Dongge Cave record from 15.5-11 ka, suggesting much of the Indian Ocean monsoon region responded similarly to the major climate changes of the last deglaciation. The transitions into the Younger Dryas and to a lesser extent the Bolling are remarkably gradual in M1-5, as they are in all other Asian speleothem records, occurring over several centuries. These gradual transitions are in striking contrast to high-resolution records from around the North Atlantic basin where the transitions are extremely abrupt and generally occur in under a century. This spatially variable pattern of climate change is consistent with an Atlantic origin for these deglacial climate events. (c) 2007 Elsevier B.V. All rights reserved.