SHI Xue-fa1,2, LIU Sheng-fa1,2, QIAO Shu-qing1,2, YAO Zheng-quan1,2, LIU Yan-guang1,2
1. Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, SOA, Qingdao Shandong 266061, China;
2. Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao Shandong 266061, China
Abstract: Geochemical characteristics and distribution pattern of surface sediments from eastern China seas were studied and the paleoclimate evolution since the mid-Holocene were further reconstructed in this paper. The results showed that the SiO2 content, with a mean up to 63%, are highest in the sediment samples, Al2O3 content is the next to SiO2, having a mean of 12%, consequently, the total of other elements take up a very small proportion. R-factor analysis revealed the compositions of major and trace elements are controlled by multiple factors, such as terrigenous clastic matter, marine biogenous sediment, marine chemistry and diagenesis. The Yangtze River and the Yellow River carried dominating terrigenous sediments to the sea field, a mathematic method model was produced to calculate the sediment provenance quantitatively. Based on the model and the tracers, the boundary was determined at 123°E and 32°N, the Yellow River controlled the most area of the Bohai Sea and the Yellow Sea, while the Yangtze River mainly controlled the inner shelf of the East China Sea. Geochemistry proxies including CIA, Ba/Sr and CaO/MgO were chosen to reconstruct the paleoclimate evolution in the eastern China seas, we found that from 8300 a BP to 4200 a BP the climate was moderately warm and humid. From 4200 a BP to 2300 a BP the climate was cool and dry, with large fluctuations between cool-dry(3700 a BP, 2850 a BP and 2400 a BP) and warm-wet(3250 a BP and 2650 a BP). Since 2300 a BP, our records indicated that the climate had gradually become warmer, although some cold events centered by the Little Ice Age interrupted this warming trend. We also found significant 238 yr cycles in our CIA records that imply a possible solar influence on the regional climate changes since the mid-Holocene.
Keywords: eastern China seas sediment geochemistry provenance paleoclimate
E-Mail: xfshi@fio.org.cn
Bulletin of Mineralogy, Petrology and Geochemistry Vol.34, No.5, 2015, page 885-894
