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G-Cubed: Geochemistry, Geophysics, Geosystems

 

Keywords

  • Arabian Sea
  • Holocene paleoclimate
  • Indus
  • geochemistry
  • neodymium and strontium isotopes

Index Terms

  • Biogeosciences: Marine systems (4800)
  • Geochemistry: Alteration and weathering processes (3617)
  • Hydrology: Sediment transport (4558)
Abstract
Cited By (0)
 

Abstract

GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, VOL. 13, Q01008, 26 PP., 2012
doi:10.1029/2011GC003845

Geochemical record of Holocene to Recent sedimentation on the Western Indus continental shelf, Arabian Sea

Key Points
  • Some widely used geochemical proxies not suitable for weathering
  • Reworking is an important process in the Indus region
  • Continental shelves not necessarily good places for continental weathering

David R. Limmer

School of Geosciences, University of Aberdeen, Meston Building, Aberdeen AB24 3UE, UK

Philipp Böning

ICBM Microbiogeochemistry, University of Oldenburg, D-26129 Oldenburg, Germany

Liviu Giosan

Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA

Camilo Ponton

Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA

Cornelia M. Köhler

School of Geosciences, University of Aberdeen, Meston Building, Aberdeen AB24 3UE, UK

Matthew J. Cooper

School of Ocean and Earth Sciences, National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK

Ali R. Tabrez

National Institute of Oceanography, ST-47 Block 1, Clifton, Karachi 75600, Pakistan

Peter D. Clift

School of Geosciences, University of Aberdeen, Meston Building, Aberdeen AB24 3UE, UK

We present a multiproxy geochemical analysis of two cores recovered from the Indus Shelf spanning the Early Holocene to Recent (<14 ka). Indus-23 is located close to the modern Indus River, while Indus-10 is positioned ∼100 km further west. The Holocene transgression at Indus-10 was over a surface that was strongly weathered during the last glacial sea level lowstand. Lower Holocene sediments at Indus-10 have higher εNd values compared to those at the river mouth indicating some sediment supply from the Makran coast, either during the deposition or via reworking of older sediments outcropping on the shelf. Sediment transport from Makran occurred during transgressive intervals when sea level crossed the mid shelf. The sediment flux from non-Indus sources to Indus-10 peaked between 11 ka and 8 ka. A hiatus at Indus-23 from 8 ka until 1.3 ka indicates non-deposition or erosion of existing Indus Shelf sequences. Higher εNd values seen on the shelf compared to the delta imply reworking of older delta sediments in building Holocene clinoforms. Chemical Index of Alteration (CIA), Mg/Al and Sr isotopes are all affected by erosion of detrital carbonate, which reduced through the Holocene. K/Al data suggest that silicate weathering peaked ca. 4–6 ka and was higher at Indus-10 compared to Indus-23. Fine-grained sediments that make up the shelf have geochemical signatures that are different from the coarser grained bulk sediments measured in the delta plain. The Indus Shelf data highlight the complexity of reconstructing records of continental erosion and provenance in marine settings.

Received 24 August 2011; accepted 6 December 2011; published 14 January 2012.

Citation: Limmer, D. R., P. Böning, L. Giosan, C. Ponton, C. M. Köhler, M. J. Cooper, A. R. Tabrez, and P. D. Clift (2012), Geochemical record of Holocene to Recent sedimentation on the Western Indus continental shelf, Arabian Sea, Geochem. Geophys. Geosyst., 13, Q01008, doi:10.1029/2011GC003845.

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