High Resolution Oxygen Isotope Straigraphy for the Last 150,000 Years in the Southern South China Sea:Core MD972151

Abstract

A detailed high-resolution oxygen isotope stratigraphy over the last two glacial-interglacial cycles in the southern South China Sea is presented, based upon analysis of Globigerinoides sacculifer (planktic foraminifera) in Core MD972151. Major characteristic isotopic events were identified and correlated to the standard SPECMAP chronology. In addition, radiocar bon dating and a few biostratigraphic, geomagnetic and tephrochronologic markers were employed to enhance the reliability and resolution of the age model. The tephra layer of the Toba Eruption at 71 ka helps to anchor the boundary of Stages 5/4, and provides a yardstick correlating to the cold period between interstadials 19 and 20 identified in the GISP2 Greenland ice core. The last appearance of pink Globigerinoides ruber and the Blake magnetic polarity event in the lower part of the core helped us to locate the transition of Stage 6/Se. Our high-resolution oxygen isotope stratigraphy, however, indicates that the age of the Blake magnetic reversal occurred during the Stage 6/Se transition instead after the warmth peak of the isoto pic event Se. The resulting age model shows that the 26.54 m sequence from Core MD972151 provides a continuous record from 153 to 0.94 ka, with sedi mentation rates varying between 5.6 and 78 cm/kyr. The temporal resolu tion of the isotopic record is about 60 -150 years per sample for the upper part of the core and 250 years for the lower part, respectively.

Late Quaternary Planktic Foraminifer Fauna andMonsoon Upwelling Records from the Western South China Sea, Near the Vietnam Margin (IMAGESMD012394)

“…2b) reveals that glacial/interglacial variations of 1.5‰, in agreement with previous results (Thunell et al 1992;Schonfeld and Kudrass 1993;Lee et al 1999;Chen et al 2005;Zhao et al 2006). The mean values (~-2.11‰) for MIS 5 and Holocene (0 -4 ka) are also consistent with previously reported data.…”

Toward establishing a maritime proxy record of the East Asian summer monsoons for the late Quaternary

“…The last appearance datum (LA) of pink Globigerinoides ruber at about 120 ka has been considered a good biostratigraphic marker in the western Paci¢c (Thompson et al, 1979). Lee et al (1999) reported recently that the age of this datum is 127 ka at Site MD972151 in the southwest SCS. The last occurrence of pink G. ruber at Site MD972142 was found at a subdepth of 910 cm.…”

Age Model and Oxygen Isotope Stratigraphy of Site ODP1202 in the Southern Okinaw a Trough, Northwestern Pacific

“…The age of the bottom of the acme zone in the Pacific has been dated to be at 85 ka (Berggren et al 1995). The absence of pink Globigerinoides ruber, on the other hand, delimits the sequence to be younger than 127 ka (Lee et al 1999;Wei et al 2000). Moreover, the persistent appearance of orange-colored tiny Zeaglobigerina rubescens indicates that the sediments recovered are young and fresh (Parker and Berger 1971).…”