Radiolarian distribution and its response to the monsoonal and oceanographic changes of the Northwestern Bay of Bengal during the last 7000 years

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Geobios Pub Date : 2025-12-01 Epub Date: 2025-07-04 DOI:10.1016/j.geobios.2025.06.004

Veena Gopika Viswam , Neelakantan Ravindran Nisha , Kavya Aravind , Naveen Gandhi

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引用次数: 0

Abstract

The present investigation is the first contribution on the temporal distribution pattern of radiolarian fauna from the Northwestern Bay of Bengal (BoB). The present core spans up to 25 cal kyr BP based on the AMS ¹⁴C radiocarbon dates obtained from planktonic foraminifera. The study documented the paleomonsoonal events for the past 7 kyr based on the quantitative distribution pattern of radiolarians. We report 26 radiolarian species among which 11 species are reported for the first time from the Northwestern BoB. In the present study, suborder Spumellaria was dominant (99.3%) over the suborder Nassellaria (0.6%). The radiolarian occurrence is noticed up to 7272 cal yr BP in the study area. In the Northwestern BoB, a strong monsoonal and high river discharge period is recorded during 7272–4424 cal yr BP, whereas weaker monsoonal period and aridification with episodes of increased upwelling activity is noticed during 4424–2678 cal yr BP. Simultaneous occurrence of intense monsoonal precipitation and upwelling activity is noticed between 2678 and 1000 cal yr BP. Alternate episodes of enhanced and decreased monsoonal activity associated with decreased upwelling events are recorded between 1000 and 800 cal yr BP and 800-Present time intervals, respectively. Thus radiolarian distribution in the study area was strongly influenced by the riverine discharge due to monsoonal precipitation and oceanographic conditions. Through this study, we propose the possibility of using radiolarian fauna as a proxy for paleomonsoonal as well as paleoceanographic studies.

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近7000年来孟加拉湾西北部放射虫分布及其对季风和海洋变化的响应

本文首次对西北孟加拉湾放射虫区系的时间分布格局进行了研究。根据浮游有孔虫的AMS 14C放射性碳测年，现今岩心跨度可达25 calkyr BP。该研究基于放射虫的数量分布模式记录了过去7年的古季风事件。本文报道了26种放射虫，其中11种为首次报道。在本研究中，Spumellaria亚目占优势（99.3%），而Nassellaria亚目占优势（0.6%）。研究区在7272 calyr BP处发现放射虫。7272 ~ 4424 cal yr BP为西北地区强季风期和高流量期，4424 ~ 2678 cal yr BP为弱季风期和干旱化期，上升流活动增加。在2678 ~ 1000 cal yr BP之间，强烈的季风降水和上升流活动同时发生。与上升流事件减少相关的季风活动增强和减弱交替事件分别记录在1000 - 800 cal yr BP和800- present时间间隔之间。因此，研究区放射虫的分布受季风降水和海洋条件下河流流量的强烈影响。通过这项研究，我们提出了用放射虫动物群作为古季风和古海洋学研究的代理的可能性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Geobios 地学-古生物学

CiteScore

3.30

自引率

6.20%

发文量

审稿时长

6-12 weeks

期刊介绍： Geobios publishes bimonthly in English original peer-reviewed articles of international interest in any area of paleontology, paleobiology, paleoecology, paleobiogeography, (bio)stratigraphy and biogeochemistry. All taxonomic groups are treated, including microfossils, invertebrates, plants, vertebrates and ichnofossils. Geobios welcomes descriptive papers based on original material (e.g. large Systematic Paleontology works), as well as more analytically and/or methodologically oriented papers, provided they offer strong and significant biochronological/biostratigraphical, paleobiogeographical, paleobiological and/or phylogenetic new insights and perspectices. A high priority level is given to synchronic and/or diachronic studies based on multi- or inter-disciplinary approaches mixing various fields of Earth and Life Sciences. Works based on extant data are also considered, provided they offer significant insights into geological-time studies.