Radiolarian record to paleoecological environment change events over the past 1.2 MaBP in the southern South China Sea |
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Authors: | Lihong?Yang Email author" target="_blank">Muhong?ChenEmail author Rujian?Wang Fan?Zhen |
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Institution: | (1) The South China Sea Institute of Oceanology, Chinese Academy of Sciences, 510301 Guangzhou, China;(2) Key Laboratory of Marine Geology, Ministry of Education, Tongji University, 200092 Shanghai, China |
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Abstract: | This note studies the Radiolarian fossil groups since 1.2 MaBP in ODP leg 184 site 1143, the southern South China Sea (SCS).
The result shows that radiolarian abundance experienced a significant variation: before 0.9 MaBP it remained at the extremely
low level, but increased with low extent between 0.9–0.65 Ma, which corresponded to the Mid-Pleistocene Transition stage,
and it increased rapidly after 0.65 MaBP. During the whole process, the average abundance became higher and higher in each
stage, and showed regularly periodic fluctuations. The obvious increase after 0.65 MaBP is inferred to result from the enhanced
upwelling in this region, which was induced by the intensified monsoon circulation after the “Mid-Pleistocene Transition”.
An outstanding result of the spectral analyses is that a long oscillation of ∼ 0.2 Ma cycle was found in the records of radiolarian
abundance and complex diversity, which corresponds well to the result of other paleoceanographic indexes. This probably indicated
a special cycle characteristic of paleoecological environment evolution in this area. In addition, all of the radiolarian
indexes show an obvious boundary in about 0.47 MaBP, indicating the abrupt variation of the community structure and radiolarian
abundance level before and after 0.47 MaBP. So we suppose that there existed a distinct change event of oceanic ecology environment
during that period. |
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Keywords: | radiolarian southern South China Sea distribution environmental change site 1143 |
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