Abstract Title: Indian Monsoon Variability and Associated Changes in The Bay of Bengal Over the Last ~33 Kyr: Records from Planktic Foraminifera
Abstract Submitted to: PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY
Abstract Text:
We report a planktic foraminiferal record from the western side of the OMZ, located off the coast of Visakhapatnam in the Bay of Bengal (BoB) (SK 336 GC-2, water depth; 814 m). These results show a significant monsoonal variability for the last ~33 kyr BP, as changes observed from Globigerinoides ruber (40 %), Globigerina bulloides (36 %), Neogloboquadrina dutertrei (27 %), Globorotalia menardii (26 %), and Globoturborotalita rubescens (22 %), Trilobatus sacculifer (5%). An increase in the relative abundance of G. bulloides and N. dutertrei suggests enhanced upwelling and productivity and G. ruber and T. sacculifer is attributed to strong stratification and nutrient-poor water. Based on the faunal proxy record (i.e., mixed surface layer eutrophic and oligotrophic species and G. bulloides/ G. ruber ratio) and mineral magnetism, climatic phases of alternating southwest (SW) and northeast (NE) Indian monsoon are identified for last ~33 kyr BP from the BoB. The abundant oligotrophic species and increase in magnetic susceptibility(χlf) (during ~15ka, ~10 to 9 ka, ~1.2 ka, ~113 years BP to the present) exhibit the warming period resulting in strong SW monsoon. The last glacial maximum (~22–19 kyr BP) suggests that vertical mixing is driven by NE-intensified monsoon wind circulation. The time period, which corresponds to Younger Dryas, exhibits productivity increases as a result of abundant eutrophic species, and its modest G. bulloides/G. ruber ratio with decreased χlf indicates that the surface water was less stratified. These results suggest that surface hydrography and productivity in the Bay of Bengal are controlled by variations in the pattern of precipitation during the SW and NE monsoons.
Keywords: Planktic foraminifera, Bay of Bengal, ecology, productivity, OMZ.
Komal Shinde
Description
Funded by:
Current Institute of Study/Organization: Vellore Institute of Technology, VIT Chennai, Tamil Nadu, India
Currently Pursuing: Doctorate
Country: IN