2. Toward a High-Resolution Stable Isotope Stratigraphy of the Last 1.1 m.y.: Site 1144, South China Sea¹

Christian Bühring,² Michael Sarnthein,² and Helmut Erlenkeuser³

ABSTRACT

Narrow-spaced oxygen and carbon stable isotope records of the planktonic foraminifer Globigerinoides ruber (white) were obtained at Ocean Drilling Program Leg 184 Site 1144 to establish a first record of high-resolution Pleistocene monsoon variability on orbital to centennial timescales in the northern South China Sea. The new records extend from the Holocene back to marine isotope Stage (MIS) 34 (1.1 Ma). Sedimentation rates average 0.56 m/k.y. for the upper Matuyama and Brunhes Chrons and increase to 1.8 m/k.y. over the last 100 k.y. Stable isotope records thus reach an average time resolution of 270–500 yr for the last 375 k.y. and 570 yr further back to 700 ka. On the other hand, major stratigraphic gaps were identified for peak warm Stages 5.5, 7.5 (down to 8.4), 11.3, and 15.5. These gaps probably resulted from short-lasting events of contour current erosion induced by short-term enhanced incursions of Upper Pacific Deep Water near the end of glacial terminations. A further major hiatus extends from MIS 34 to MIS 73(?). The long-term variations in monsoon climate were largely dominated by the 100-k.y. eccentricity cycle. Planktonic ¹³C values culminated near 30, 480, and 1035 ka and reflect an overlying 450-k.y. eccentricity cycle of minimum nutrient concentrations in the surface ocean. Superimposed on the orbital variations, millennial-scale cycles were prominent throughout the last 700 k.y., mainly controlled by short-term changes in monsoon-driven precipitation and freshwater input from mainland China. During the last 110 k.y. these short-lasting oscillations closely match the record of 1500-yr Dansgaard-Oeschger climate cycles in the Greenland ice core record.

¹Bühring, C., Sarnthein, M., and Erlenkeuser, H., 2004. Toward a high-resolution stable isotope stratigraphy of the last 1.1 m.y.: Site 1144, South China Sea. In Prell, W.L., Wang, P., Blum, P., Rea, D.K., and Clemens, S.C. (Eds.), Proc. ODP, Sci. Results, 184 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/184_SR/205/205.htm>. [Cited YYYY-MM-DD]

²Institut für Geowissenschaften, University of Kiel, Olshausenstrasse 40, D-24118 Kiel, Germany. Correspondence author: ms@gpi.uni-kiel.de

³Leibniz-Labor für Altersbestimmung und Isotopenforschung, University of Kiel, Olshausenstrasse 40, D-24118 Kiel, Germany.

Initial receipt: 10 August 2001
Acceptance: 15 March 2004
Web publication: 3 December 2004
Ms 184SR-205