Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

Journal of Earth system science

Rajeev Saraswat1¹  M Manasa1¹  Rajiv Nigam1¹ 

[1] Micropaleontology Laboratory, Geological Oceanography Division, CSIR – National Institute of Oceanography, Goa, India.$$

关键词: Benthic foraminifera;    Bay of Bengal;    morpho-groups;    Corg;    agglutinated;    calcareous foraminifera;    paleomonsoon;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Temporal changes in benthic foraminiferal morpho-groups were suggested as an effective proxy to reconstructpast monsoon intensity from the Arabian Sea. Here, in order to test the applicability of temporalvariation in morpho-groups to reconstruct past monsoon intensity from the Bay of Bengal, we havedocumented recent benthic foraminiferal distribution from the continental shelf region of the northwesternBay of Bengal. Based on the external morphology, benthic foraminifera were categorized intorounded symmetrical (RSBF) and angular asymmetrical benthic foraminifera (AABF). Additionally, afew other dominant groups were also identified based on test composition (agglutinated, calcareous) andabundance (Asterorotalids and Nonions). The relative abundance of each group was compared with theambient physico-chemical conditions, including dissolved oxygen, organic matter, salinity and temperature.We report that the RSBF are abundant in comparatively warm and well oxygenated waters of lowsalinity, suggesting a preference for high energy environment, whereas AABF dominate relatively cold,hypersaline deeper waters with low dissolved oxygen, indicating a low energy environment. The agglutinatedforaminifera, Asterorotalids and Nonions dominate shallow water, low salinity regions, whereasthe calcareous benthic foraminiferal abundance increases away from the riverine influx regions. Foodavailability, as estimated from organic carbon abundance in sediments, has comparatively less influenceon faunal distribution in the northwestern Bay of Bengal, as compared to dissolved oxygen, temperatureand salinity. We conclude that the factors associated with freshwater influx affect the distributionof benthic foraminiferal morpho-groups in the northwestern Bay of Bengal and thus it can be used toreconstruct past monsoon intensity from the Bay of Bengal.

【 授权许可】

Unknown