50,000-year Late Quaternary Biogenic Sedimentation, Sea Surface Temperature, and Land Erosion Records From the Southern Papua New Guinea (IMAGES MD052928)

We present 50,000-year late Quaternary records of carbonate and total organic carbon (TOC), TEX86-SST and Uk'37-SST, and Branched Isoprenoid Tetraether (BIT) from core MD052928 (11°17.26Ś, 148°51.60É, water depth: 2250m) taken from the southeastern Papua New Guinea slope during the PECTEN cruise in 2005. The age model of the core is constructed by AMS-14C dating of planktic foraminifers, benthic foraminifer oxygen isotope stratigraphy, and paleomagnetic intensity. We found that the carbonate and TOC contents showed glacial-interglacial variations. The carbonate contents range between 15%- 50%, with higher contents in the Holocene and lower in MIS (Marine Isotope Stage) 2-3. The carbonate contents also show high frequency oscillations that mimic millennial-scale climate changes during the last deglaciation and MIS 2-3. The carbonate contents correlate well with the BIT index measured from the same core. Low carbonate events coincide with BIT indices that indicate more inputs of terrestrial organic matters, suggesting noticeable changes of soil erosion and terrestrial fluvial input on land nearby. The TOC contents range between 0.2%-0.4%, and show higher contents during MIS 2-3. High TOC contents are associated with BIT indices that reflect higher input of terrestrial organic matters. We have also conducted sea surface temperature (SST) analyses by testing two proxies: glycerol dibiphytanyl glycerol tetraether membrane lipid composition of marine crenarchaeota (TEX86) and alkenone (Uk'37). While both proxies yield similar SST during the LGM (27-28° C), SST in the Holocene derived from TEX86 is 2° C higher than that derived from Uk'37(31° C vs 29° C). Our records suggest that higher input of terrestrial organic matter is coupled to intensified soil erosion during cold periods. Whether our records implicate global climate (Antarctic vs. Arctic) or regional processes (e.g. land precipitation, high mountain glacier expansion) remains to be further investigated.