Advances in Earth Science ›› 2007, Vol. 22 ›› Issue (9): 914-921. doi: 10.11867/j.issn.1001-8166.2007.09.0914

Special Issue: IODP

• Articles • Previous Articles     Next Articles

Paleoclimatic Instability During the MidPleistocene Transition: Implications from Foraminiferal Stable Isotope at ODP Site1144 ,Northern South China Sea

JIN Hai-yan,JIAN Zhi-min   

  1. State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China
  • Received:2007-08-04 Revised:2007-08-20 Online:2007-09-15 Published:2007-09-10

JIN Hai-yan,JIAN Zhi-min. Paleoclimatic Instability During the MidPleistocene Transition: Implications from Foraminiferal Stable Isotope at ODP Site1144 ,Northern South China Sea[J]. Advances in Earth Science, 2007, 22(9): 914-921.

The midPleistocene climate transition (MPT) is a period in geologic history marked by a gradual change in climate periodicity from 40 ka to 100 ka at approximately 0.9 Ma BP, around the marine isotope stages (MIS) 22/23 boundary. Here we present a high resolution record (~290 a sampling interval) of foraminiferal stable isotopes during 0.8~1.0 Ma at this site. Our data indicated that the Asian monsoon strengthened after the MPT, resulting a deepened thermocline. The depth of the thermocline (DOT) and the nutrientcline were found to be deeper during the glacials than in interglacials before the MPR. After the MPR, the DOT and the nutrientcline became deeper in interglacials than in glacial periods. On the orbital time scale, the surface water change synchronized with the bottom water change. However, on the millennial time scale, spectral analysis of foraminiferal oxygen and carbon isotope data revealed dominant periodicities at ~0.8 ka and ~1.4 ka, indicating the climatic instability during the MPT. Furthermore, the amplitude changes of the millennialscale climate instability were amplified after 0.9 Ma. Most of the strong cyclic signals occurred during the interglacials during the MPT, which is different from the millennial climatic instability during the later Pleistocene. Therefore, our isotopic results confirm the previous conclusion of color reflectance (CR) analysis at this site.

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