AMS 14 C dating controlled records of monsoon and Indonesian throughflow variability from the eastern Indian Ocean of the past 32,000 years

Abstract:

Zi-Ye Li ^a, Min-Te Chen ^b, Hou-Jie Wang ^a, Sheng-Fa Liu ^c, Xue-Fa Shi ^c

^a College of Marine Geosciences, Ocean University of China, Qingdao 266100, P.R. China

^b Institute of Applied Geosciences, National Taiwan Ocean University, Keelung, Taiwan 20224, ROC

^c First Institute of Oceanography, SOA, Qingdao 266100, P.R. China

 

 Indonesian throughflow (ITF) is one of the most important currents responsible for transporting heat and moisture from the western Pacific to the Indian Oceans. The ITF is also well-known as effectively in modulating the global climate change with the interactions among ENSO and Asian monsoons. Here we present an AMS 14C dating controlled sea surface temperature (SST) record from core SO184-10043 (07°18.57′S, 105°03.53′E), which was retrieved from 2171m water depth at a north-south depression located at the southeastern offshore area of Sumatera in the eastern Indian Ocean. Based on our high-resolution SST using Mg/Ca analyses based on planktonic foraminifera shells of Globigerinoides ruber and alkenone index, U ^k’₃₇-SST, oxygen isotope stratigraphy, and AMC ¹⁴C age-controls, our records show that, during the past 32,000 years, the SSTs were decreased which imply weaker ITF during Marine Isotope Stage (MIS) 2 and 3. The weaker UTF may respond to strengthened northeast monsoon during the boreal winter. During 21 to 15ka, the southeast monsoon had been stronger and the northeast monsoon was relatively weaker. During 15 to 8ka, rapid sea level rising may allow the opening of the gateways in the Makassar Strait and Lombok Strait that may have further strengthened the ITF. During the early Holocene, the northeast and southeast monsoons seem to be both strengthened. We will discuss the implications of the hydrographic variability and their age uncertainties in this paper during the meeting.