210Pb, 230Th, and 10Be in Central Indian Basin seamount sediments: Signatures of degassing and hydrothermal alteration of recent origin

Nath, B. Nagender; Borole, D.V.; Aldahan, Ala; Patil, Shramik; Mascarenhas‐Pereira, M.B.L.; Possnert, Göran; Ericsson, Tore; Ramaswamy, V.; Gupta, Sandeep K.

doi:10.1029/2008gl033849

Cited by 17 publications

(23 citation statements)

References 30 publications

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“…, 2006), native aluminium content (Iyer et al. , 2007) and signatures of degassing (Nath et al. , 2008) suggest hydrothermal alteration of recent origin in some locations.…”

Section: Geological Setting Of the Central Indian Basinmentioning

confidence: 99%

Bacterial response to contrasting sediment geochemistry in the Central Indian Basin

et al. 2010

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In order to investigate whether geochemical, physiographic and lithological differences in two end-member sedimentary settings could evoke varied microbe-sediment interactions, two 25 cm long sediment cores from contrasting regions in the Central Indian Basin have been examined. Site TVBC 26 in the northern siliceous realm (10°S, 75AE5°E) is organic-C rich with 0AE3 ± 0AE09% total organic carbon. Site TVBC 08 in the southern pelagic red clay realm (16°S, 75AE5°E), located on the flank of a seamount in a mid-plate volcanic area with hydrothermal alterations of recent origin, is organic-C poor (0AE1 ± 0AE07%). Significantly higher bacterial viability under anaerobic conditions, generally lower microbial carbon uptake and higher numbers of aerobic sulphur oxidizers at the mottled zones, characterize core TVBC 26. In the carbon-poor environment of core TVBC 08, a doubling of the 14 C uptake, a 250 times increase in the number of autotrophic nitrifiers, a four-fold lowering in the number of aerobic sulphur oxidizers and a higher order of denitrifiers exists when compared with core TVBC 26; this suggests the prevalence of a potentially autotrophic microbial community in core TVBC 08 in response to hydrothermal activity. Microbial activity at the northern TVBC 26 is predominantly heterotrophic with enhanced chemosynthetic activity restricted to tan-green mottled zones. The southern TVBC 08 is autotrophic with increased heterotrophic activity in the deepest layers. Notably, the bacterial activity is generally dependent on the surface productivity in TVBC 26, the carbon-rich core, and mostly independent in TVBC 08, the carbon-poor, hydrothermally influenced core. The northern sediment is more organic sink-controlled and the southern sediment is more hydrothermal source-controlled. Hydrothermal activity and associated rock alteration processes may be more relevant than organic matter delivery in these deep-sea sediments. Thus, this study highlights the relative importance of hydrothermal activity versus organic delivery in evoking different microbial responses in the Central Indian Basin sediments.

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“…, 2006), native aluminium content (Iyer et al. , 2007) and signatures of degassing (Nath et al. , 2008) suggest hydrothermal alteration of recent origin in some locations.…”

Section: Geological Setting Of the Central Indian Basinmentioning

confidence: 99%

Bacterial response to contrasting sediment geochemistry in the Central Indian Basin

et al. 2010

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“…These two synchronous radiolarian biostratigraphic datum levels have been widely used in reconstructing the chronology of late Quaternary sediments of the CIB (Gupta , , ; Nath et al . ). B. invaginata is the index species of the very first and topmost zone of the Neogene radiolarian biostratigraphy.…”

Section: Discussionmentioning

confidence: 97%

“…; Nath et al . ). Here we present the first carbonate‐based palaeoceanographic record from the CIB, which was made possible by sampling of the seamount top, which is situated close to the lysocline.…”

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confidence: 97%

Record of carbonate preservation and the Mid‐Brunhes climatic shift from a seamount top with low sedimentation rates in the Central Indian Basin

Nath¹,

Sijinkumar²,

Borole

et al. 2012

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R. 2013 (July): Record of carbonate preservation and the Mid-Brunhes climatic shift from a seamount top with low sedimentation rates in the Central Indian Basin.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 ( 230 Thexcess, AMS 14 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 Buccinosphaera invaginata (180 ka) and coccolith Emiliania huxleyi (268 ka) and the last appearance datum (LAD) of the radiolarian Stylatractus universus (425 ka) were used. A monsoon-induced productivity increase was inferred from carbonate, organic carbon and d 13 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 Globorotalia menardii and other resistant species beginning from marine isotope stage (MIS) 11 and the proliferation of coccolith Gephyrocapsa 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.

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“…The oxygenated bottom water of the CIB promotes the adsorption of P onto the surface of iron oxyhydroxides. The distribution of P Fe (Figure ) and total Fe (Figure S4) indicates that the concentration increases toward the southern part of the basin, where pelagic red clays are dominant and the sediments from this region bear the signature of hydrothermal activity (A. Das, Sujith, et al, ; Iyer et al, ; Mascarenhas‐Pereira & Nath, ; Nath et al, ). This influence of hydrothermal activity results in the enrichment of Fe in the pelagic region.…”

Section: Discussionmentioning

confidence: 99%

“…The possibility of an intraplate volcanism due to reactivation of tectonic activity was reported at this station which is located on the flanks of a seamount and is in the vicinity of 76°30′E fracture zone (Mascarenhas‐Pereira et al, ). The depletion in C org , dissolution features of radiolarian skeletons, presence of altered minerals such as smectite and zeolites, and distinctly different magnetic properties in the altered sediments have been attributed to the hydrothermal alteration in the same location (Nath et al, ). The sediments have all the geochemical characters typical of metalliferous nature (Mascarenhas‐Pereira & Nath, ).…”

Section: Discussionmentioning

confidence: 99%

Distribution and Diagenesis of Phosphorus in the Deep‐Sea Sediments of the Central Indian Basin

et al. 2018

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A regional solid‐phase phosphorus (P) speciation study in the Central Indian Basin (CIB) was carried out to elucidate the spatial distribution of sedimentary P species and P diagenesis in an oligotrophic setting. The results show that P enrichment is in the order of biogenic (Pbio) > authigenic (Pauth) > iron bound (PFe) > detrital (Pdet) > organic (Porg) P. The higher concentrations of Pbio are found in siliceous oozes, which are attributed to high biological productivity in the overlying waters compared to pelagic clay region. High Pauth and Pdet contents with low molar Corg/Preact ratios in the pelagic/red clays indicate the deposition of calcium fluorapatite and refractory material from the atmospheric input. The oxygenated bottom water promotes adsorption of P onto iron oxyhydroxides making the PFe an important sink. Remobilization of P within the sediments is limited because of well‐oxygenated conditions and an efficient adsorption by iron oxyhydroxides and clay‐sized sediments. A twofold increase in Ptotal and P‐species is observed in hydrothermally altered, ferruginous sediments from a seamount flank suggesting an important role of hydrothermal processes in P cycling. The calculated P accumulation rate in the present study ranges between 0.6 and 11.7 μmol·cm−2·kyr−1. The burial flux of P for the entire CIB (5.7 × 106 km2) is 0.01 × 1010 mol P per year which accounts for 0.05% of the global flux. The benthic P fluxes from the seawater to the sediments in the area range between 0.0093 and 0.133 μmol·cm−2·kyr−1 indicating that the CIB sediments are an important sink for P.

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²¹⁰Pb, ²³⁰Th, and ¹⁰Be in Central Indian Basin seamount sediments: Signatures of degassing and hydrothermal alteration of recent origin

Cited by 17 publications

References 30 publications

Bacterial response to contrasting sediment geochemistry in the Central Indian Basin

Bacterial response to contrasting sediment geochemistry in the Central Indian Basin

Record of carbonate preservation and the Mid‐Brunhes climatic shift from a seamount top with low sedimentation rates in the Central Indian Basin

Distribution and Diagenesis of Phosphorus in the Deep‐Sea Sediments of the Central Indian Basin

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