Journal of Tropical Oceanography ›› 2019, Vol. 38 ›› Issue (6): 51-61.doi: 10.11978/2019010CSTR: 32234.14.2019010

• Marine Biology • Previous Articles     Next Articles

Response of planktonic foraminifera to Holocene marine environmental changes in the Andaman Sea

ZHANG Lingzhi1,2, XIANG Rong1(), TANG Linggang1,2, YANG Yiping1, ZHONG Fuchang1,2   

  1. 1. CAS Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Guangzhou 510301, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2019-01-15 Revised:2019-04-01 Online:2019-11-20 Published:2019-11-26
  • Contact: Rong XIANG E-mail:rxiang@scsio.ac.cn
  • Supported by:
    National Natural Science Foundation of China(91228207);National Natural Science Foundation of China(41476040);Strategic Leading Science & Technology Programme, Chinese Academy of Sciences(XDA11030104)

Abstract:

Through analysis of planktonic foraminifera in a gravity core ADM-C1 from the Andaman Sea, the response of planktonic foraminifera to Holocene marine environmental changes in the sea was discussed. The result shows that the planktonic foraminiferal communities in this region are dominated by tropical warm-water species Globigerinoides ruber, Globigerinoides sacculifer, Neogloboquadrina dutertrei, and Pulleniatina obliquiloculata. The relative abundance of G. ruber shows a gradual decreased trend from the early Holocene to present, which is roughly opposite to that of G. sacculifer. The relative abundance of N. dutertrei is higher during 11 to 7.9 ka BP (before present), generally lower during 7.9 to 3.8 ka BP, and then gradually increases after 3.8 ka BP. P. obliquiloculata shows an almost opposite trend to that of N. dutertrei. Our result indicates no obvious Pulleniatina Minimum Eventduring the late Holocene, occurs in the Andaman Sea. Q-mode factor analyses of planktonic foraminifera in the core ADM-C1 identify three stages in marine environmental changes during the Holocene. During the early Holocene (11-7.9 ka BP), planktonic foraminifera assemblage was dominated by G. ruber, N. dutertrei and G. bulloides, which reflected that strong summer monsoon and precipitation led to lower sea surface salinity, while the influence of winter monsoon was also strong during this stage. During 7.9-3.8 ka BP, G. ruber, P. obliquiloculata and Globigerinella aequilateralis dominated, indicating lower sea surface salinity during this period. Meanwhile, there was obviously increase in abundance of subsurface water species, reflecting strong mixing in the upper-ocean waters, possibly due to the strong Indian Ocean summer monsoon at this stage. After 3.8 ka BP, G. sacculifer, N. dutertrei and P. obliquiloculata became the dominant species. The abundance of G. ruber declined obviously, indicating that the salinity of surface sea water significantly increased during this period, which was consistent with the reduced Indian Ocean summer monsoon precipitation. The phase change of the Holocene marine environment reflected by the planktonic foraminiferal assemblages in the Andaman Sea is well consistent with the terrestrial records on the Indian Ocean summer monsoon, and it also shows good consistent with the wind intensity variation in Indian Ocean summer monsoon reflected by sensitive grain size proxy of the same core, suggesting rapid response of planktonic foraminifera to marine environmental changes in the tropical marginal seas.

Key words: Holocene, Andaman Sea, Planktonic foraminifera, Indian Ocean monsoon, Marine environment