Record of carbonate preservation and the Mid‐Brunhes climatic shift from a seamount top with low sedimentation rates in the Central Indian Basin. (12th November 2012)

• Record Type: Journal Article
• Authors: Nagender Nath, Bejugam; Sijinkumar, Adukkam V.; Borole, Dnyandev V.; Gupta, Shyam M.; Mergulhao, Lina P.; Mascarenhas‐Pereira, Maria B. L.; Ramaswamy, Venkitasubramani; Guptha, Medimi V. S.; Possnert, Göran; Aldahan, Ala; Khadge, Nandkumar H.; Sharma, Rahul
• Is Part Of: Boreas. Volume 42:Number 3(2013:Jul.)
• Page Start: 762
• Page End: 778
• Publication Date: 2012-11-12
• Subjects: Geology, Stratigraphic -- Quaternary -- Periodicals; 551.79
• DOI: 10.1111/j.1502-3885.2012.00304.x
• Languages: English
• ISSNs: 0300-9483

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>In the present investigation, an age model of carbonate‐rich cores from a seamount top in the Central Indian Basin (CIB) was constructed using both isotopic (<sup>230</sup>Th<sub>excess</sub>, AMS <sup>14</sup>C, oxygen isotopes) and biostratigraphic methods. The chronologies using the two methods are in good agreement, yielding a record of the late Middle Pleistocene to the Pleistocene–Holocene transition (550 to 11.5 ka). The first appearance datum (FAD) of the radiolarian <italic>Buccinosphaera invaginata</italic> (180 ka) and coccolith <italic>Emiliania huxleyi</italic> (268 ka) and the last appearance datum (LAD) of the radiolarian <italic>Stylatractus universus</italic> (425 ka) were used. A monsoon‐induced productivity increase was inferred from carbonate, organic carbon and δ<sup>13</sup>C records in response to the Mid‐Brunhes Climatic Shift (MBCS), consistent with an increased global productivity. While the coccolith diversity increased, a decrease in coccolith productivity was found during the MBCS. At nearly the same time period, earlier records from the equatorial Indian Ocean, western Indian Ocean and eastern Africa have shown an increased productivity in response to the influence of westerlies and increased monsoon. The influence of easterlies from Australia and the intensification of aridity are evidenced by increased kaolinite content and clay‐sized sediments in response to the MBCS. An increased abundance of <italic>Globorotalia menardii</italic> and other resistant species beginning from marine isotope stage (MIS) 11 and the proliferation of coccolith <italic>Gephyrocapsa</italic> spp. indicate increased dissolution, which is consistent with the widespread global carbonate dissolution during this period. The relatively high carbonate dissolution during the transition period of MIS 3/2 and glacial to interglacial periods (MIS 6, 7 and 8) may be due to the enhanced flow of corrosive Antarctic Bottom Water (AABW) into the CIB.</p> </abstract>