An absolute-dated stalagmite oxygen isotope record over the past 35 kyrs from southeastern Myanmar
Abstract
Chinese speleothem oxygen isotope (δ18O) records have successfully documented orbital- and millennial-scale changes of low-latitude precipitation. However, it remains debated what exactly the δ18O represents. The elucidation of the δ18O records requires a better spatial coverage of hydroclimate records in the region, particularly from sites located in the core region of the Indian Summer Monsoon, and records covering the significant climate transition, and with well-resolved age constraints. Here we present an absolute-dated stalagmite δ18O profile from caves in southeastern coastal region of Myanmar. The site is strategically located at the upstream of the moisture trajectory from the Indian Ocean (Bay of Bengal, to be specific) to inland continents including southwestern and eastern China. The record spans the major portion of the last 35,000 years, and its chronology is well determined by U-Th mass spectrometric techniques. Our record shows an enriched δ18O during the glacial time, but depleted δ18O in Holocene. A few millennial-scale oscillations are superimposed on the gradual orbital-scale changes. Such observations are consistent with those in the speleothem records from the broad Asia-Australian monsoon region. However, the highest δ18O value appears around 20,000 years ago, before the onset of the so-called 'Heinrich Stadial 1'. More dramatically, the amplitude of δ18O change from the last glacial maximum to Holocene is up to 6 per mil, which is more than twice as shown in other regional speleothem records. Myanmar speleothem record in general has confirmed the modeling observations by Pausata et al. (2011, Nature Geoscience) that the climate in southern and eastern Asia can respond rapidly to the temperature change in the North Atlantic region. However, significant features are still missing from the modeling study, for example, consequent precipitation changes after ice volume expansion and continental shelf exposure.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMPP33C1942L
- Keywords:
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- 4958 PALEOCEANOGRAPHY Speleothems