Indian Monsoon and denitrification change in the Laxmi Basin (IODP Exp. 355 Site U1456) of the eastern Arabian Sea during the last 800 kyrs

Online Access: Get full text
Author(s): Kim, Ji-Eun; Khim, B. K.; Ikehara, M.; Lee, J.
Author Affiliation(s): Primary:
Pusan National University, Busan, South Korea
Kochi University, Center for Advanced Marine Core Research, Nankoku, Japan
Volume Title: AGU 2017 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2017; American Geophysical Union 2017 fall meeting, New Orleans, LA, Dec. 11-15, 2017. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The Arabian Sea is a famous site for the basin-wide denitrification in the globe. The Western Arabian Sea has been acknowledged by its upwelling-induced denitrification related to the Indian Monsoon system (Altabet et al., 1999). It was recently reported that the denitrification in the Eastern Arabian Sea (IODP Exp. 355 Site U1456) has been persistent and consistent during the mid-Pleistocene as reflected in the bulk sediment δ15N values (Tripathi et al., 2017). Based on the age model reconstructed by δ18O stratigraphy of planktonic foraminifera (Globigerinoides ruber) together with shipboard biostratigraphic and paleomagnetic data at Site U1456 drilled in the Laxmi Basin of the Eastern Arabian Sea, the glacial-interglacial fluctuations of denitrification in association with the development of oxygen minimum zone (OMZ) were resolved in the context of Indian Monsoon activity. One of striking features in the Eastern Arabian Sea is that the δ15N values of bulk sediment show clear and consistent denitrification with minimum δ15N values exceeding 6 ppm even during glacial periods, when its western counterpart experienced a temporal collapse of OMZ and denitrification. The Eastern Arabian Sea is fed not only by the upwelling-induced productivity in the western margin during the summer monsoon but also by the high productivity during the winter monsoon, both of which maintain the increased productivity affecting the OMZ through the consumption of dissolved oxygen by the degradation of sinking organic particles. The Eastern Arabian Sea is further influenced by the clockwise surface currents, intermediate water ventilation change by the blockage of Antarctic Intermediate Water, limited inflow from the Red Sea/Persian Gulf, and the freshwater salinity stratification due to nearby riverine discharges, all of which make the denitrification process more complicated than the Western Arabian Sea. Nonetheless, the glacial-interglacial denitrification change in the Eastern Arabian Sea is interpreted to be linked strongly with the intensity of Indian Monsoon.
Year of Publication: 2017
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 24 Surficial Geology, Quaternary Geology; Arabian Sea; Cenozoic; Denitrification; Expedition 355; Geochemistry; IODP Site U1456; Indian Ocean; International Ocean Discovery Program; Laxmi Basin; Paleo-oceanography; Paleocirculation; Paleoclimatology; Paleoecology; Quaternary
Coordinates: N163717 N163718 E0685021 E0685020
Record ID: 2018093796
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union, Washington, DC, United States