Hydroclimate variability of central Indo-Pacific region during the Holocene

Here we present a decadal-resolved hydroclimate record covering the past 11 thousand years based on delta O-18 data of three stalagmites from Kiang Cave (TK) on the Thai-Malay Peninsula, southern Thailand. The delta O-18 values indicate wetter conditions/more rainfall during the early Holocene from 11 to 7 thousand years before present (kyr BP). A large increase of 2 parts per thousand in delta O-18 is observed from 7.0 to 6.0 kyr BP, indicating a millennial drying period followed by drought conditions between 6.0 and 5.2 kyr BP. After a long hiatus (5.2-2.7 kyr BP), delta O-18 data show a millennium-long trend toward dry conditions. An abrupt positive change of 0.8-1.0 parts per thousand in delta O-18 is noticed between 8.29 and 8.17 kyr BP, reflecting the 8.2-ka event; however, the amplitude of the delta O-18 shift is much smaller comparing to that of the event of 6.0-5.2 kyr BP. On orbital time-scales, the TK record agrees with insolation-dominated speleothem records in the Asian-Australian monsoon realm. Noticeable inconsistencies among records in the Southeast Asia region (between 8 degrees N and 4 degrees N-8 degrees S) have been documented on multi-centennial scales. Lower delta O-18 values are likely associated with the mean position of the Intertropical Convergence Zone (ITCZ). A new reconstruction of Holocene ITCZ shifts index within the central Indo-Pacific region, based on stalagmite delta O-18 records from Kiang Cave (8 degrees N) and Liang Luar Cave (8 degrees S), shows that the ITCZ played an important role in hydroclimate variability in the Asian-Australian monsoon regions. The southward shift of the ITCZ in the central Indo-Pacific region, controlled by the interhemispheric extratropical insolation gradient, may strongly correlate with the El Nino-Southern Oscillation (ENSO) activities in the Holocene. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

This study presents a decadal-resolved hydroclimate record spanning the past 11,000 years based on delta O-18 data from stalagmites in Kiang Cave on the Thai-Malay Peninsula. It reveals wetter conditions during the early Holocene and a millennial drying period followed by drought conditions. The delta O-18 values reflect climate variability over the entire Holocene period.