Lime muds and their genesis off-Northwestern India during the late Quaternary

Journal of Earth system science

B Sekar4²  V Purnachandra Rao1¹  Allan R Chivas3³  S W A Naqvi1¹  A Anil Kumar1 2¹  Pratima M Kessarkar1¹ 

[1] National Institute of Oceanography, Dona Paula 403 004, Goa, India.$$;Birbal Sahni Institute of Paleobotany, Lucknow 226 007, India.$$;Geo-QUEST Research Centre, School of Earth and Environmental Sciences, University of Wollongong, NSW 2522, Australia.$$

关键词: Lime muds;    late Quaternary;    sea level;    radiocarbon ages;    stable isotopes;    western India.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Two sediment types were found in five gravity cores collected from water depths between 56 m and 121 m along the northwestern continental margin of India: lime muds were abundant in the lower section while siliciclastic sediments dominated the upper section. Lime mud-dominated sediments in shelf cores contained 60%–75% carbonate, 0.3%–0.6% Sr and terrigenous minerals, whereas those at the shelf break were found to have < 90% carbonate, 0.6%–0.8% Sr and traces of terrigenous minerals. Aragonite needles showing blunt edges, jointed needles and needles wrapped in smooth aragonite cement were found to be common. Stable (O and C) isotopes of lime mud indicate a potentially freshwater contribution for shelf cores and purely marine contribution for those at the shelf break. Calibrated radiocarbon ages of the lime muds ranged from 17.6–11.9 ka in different cores. The results reported here suggest that the lime muds in the shallow shelf are probably reworked from the Gulf of Kachchh, whereas those at the shelf break were biodetrital, initially formed on the carbonate platform during low stands of sea level and then exported. The change in lime mud-dominated to siliciclastic-dominated sediments in the cores may be due to climate change and rapid rise in sea level during the early Holocene.

【 授权许可】

Unknown