HR: 0830h
AN: GC31B-0168    [PDF]
TI: Evidence of Younger Dryas Event in Taiwan
AU: * Yeh, H
EM: hwyeh@earth.sinica.edu.tw
AF: Yeh Hsueh-Wen, Institute of Earth Sciences, Academia Sinica, P.O. Box 1-55, Nankang, Taipei, 11529 Taiwan
AB: Younger Dryas Event, the reversal of the warming trend heading from Last Glacial Maximum to Holocene, was first discovered about three quarters of a century ago in polar region, is now known as a widespread phenomenon of human dimension. It is generally believed that the Event started in around 11,000 years and ended in around 10,000 years before present of Carbon-14 age. Here we report the progress of our search for records of the Event in a tropic to subtropical land, Taiwan. Means for investigating climatic changes such as Younger Dryas Event in region like Taiwan is difficult to come by. In principle, carbon-isotope composition of lacustrine organic sediments is one suitable proxy for the investigation. Experimental study has so far confirmed this. Presence of unusual dust-storm deposits may also be used for the investigation. It can be argued that glacial-like worlds are also dusty worlds. We have employed both means and the results are encouraging. This report concerns with the carbon-isotope study. We have been analyzing the stable carbon isotope composition of carbon-14 dated core samples from a fossil lake, Toushe Basin, in Central Taiwan. Preliminary results had suggested the presence of a record of the Event. We have recently completed an eight-meter long core samples representing about the past 12,000 years of carbon-14 ages. This is a report of the results. The results confirm unequivocally the presence of a record of Younger Dryas Event in the core. The duration of the Event appears to be about 1,000 years, from about 11000 years to 10000 years before present of C-14 ages; The Event is characterized by abrupt flipping over at both the beginning and the end and large oscillation in between. These are consistent with that of Greenland ice core results and confirm the global nature of the Event. The results indicate that the climate of Taiwan during the Event is probably much colder and dryer than it is now.
DE: 1040 Isotopic composition/chemistry
SC: Global Climate Change [GC]
MN: 2003 Fall Meeting