300-kyr foraminiferal assemblage based records of Indian monsoon evolution from two IODP 353 Sites

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http://abstractsearch.agu.org/meetings/2018/FM/PP33E-1781.html
Author(s): Ding, X.; Wang, D.; Gong, L.; Sheng, T.; Zhou, L.
Author Affiliation(s): Primary:
China University of Geosciences, Beijing, China
Other:
Peking University, Beijing, China
Volume Title: AGU 2018 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2018; American Geophysical Union 2018 fall meeting, Washington, DC, Dec. 10-14, 2018. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Results of a study on planktonic and benthic foraminifera assemblages from sediments of last 300-kyr at sites U1446 and U1448 of IODP 353 are reported here. A preliminary chronological framework established on the basis of the Toba ash, the top of pink ruber, and the bottom of E. huxleyi allows us to recognise the MIS 1-8 over the last ≈300 ka. Clear distinction in foraminiferal assemblages between glacial and interglacial stages is observed, which can be related to evolution of Indian summer monsoon. At Site U1446, the abundances of planktonic and benthic foraminifera were high during glaciations. The percentages of high productivity species (Globigerina bulloides, Globigerinita glutinata) were relatively low during these periods. On the contrary, the abundances of planktonic and benthic foraminifera were very low during interglaciations. However, the percentages of fragments and the species resistant to dissolution (Pulleniatina obliquiloculata) during these periods show almost the same trend, both with strong dissolution effect. The percentages of high productivity species were slightly higher than during glaciations. The percentage of AABF (angular asymmetrical of benthic foraminifera) that reflects high productivity and dysoxic situation of bottom water increases markedly. These new data indicate that terrigenous fresh and rich nutrition water brought by enhanced summer monsoon results in the high-productivity, stratified seawater, strong calcite dissolution and low dissolved oxygen bottom water during interglacial periods at this site. By contrast, at Site U1448, the abundances of planktonic and benthic foraminifera were higher during interglacials than glacial times, which is coincident with the percentages of high productivity species and fragments. This suggests that terrigenous fresh and rich nutrition water brought by enhanced summer monsoon can result in higher productivity during interglacials. Dissolution is also observed but it did not affect the foraminiferal assemblage characteristics at the site.
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 24 Surficial Geology, Quaternary Geology; Bay of Bengal; Cenozoic; Cores; Expedition 353; Foraminifera; Glacial environment; Glaciomarine environment; IODP Site U1446; Indian Ocean; International Ocean Discovery Program; Marine environment; Marine sediments; Microfossils; Paleo-oceanography; Paleoecology; Paleoenvironment; Quaternary; Sediments
Coordinates: N190501 N190501 E0854405 E0854405
Record ID: 2019063579
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