Bassinot, Franck C. et al. (2011): Holocene evolution of summer winds and marine productivity in the tropical Indian Ocean in response to insolation forcing; data-model comparison

Leg/Site/Hole:
ODP 117
ODP 117 723
Identifier:
2012-046920
georefid

Creator:
Bassinot, Franck C.
CNRS-CEA-USVQ-IPSL, Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France
author

Marzin, Charline
Universite de la Mediterranee, France
author

Braconnot, Pascale
author

Marti, Olivier
author

Mathien-Blard, E.
author

Lombard, F.
author

Bopp, Laurent
author

Identification:
Holocene evolution of summer winds and marine productivity in the tropical Indian Ocean in response to insolation forcing; data-model comparison
2011
Climate of the Past
Copernicus, Katlenburg-Lindau, International
7
3
815-829
The relative abundance of Globigerinoides bulloides was used to infer Holocene paleo-productivity changes on the Oman margin and at the southern tip of India. Today, the primary productivity at both sites reaches its maximum during the summer season, when monsoon winds result in local Eckman pumping, which brings more nutrients to the surface. On a millennium time-scale, however, the % G. bulloides records indicate an opposite evolution of paleo-productivity at these sites through the Holocene. The Oman Margin productivity was maximal at approximately 9 ka (boreal summer insolation maximum) and has decreased since then, suggesting a direct response to insolation forcing. On the contrary, the productivity at the southern tip of India was minimum at approximately 9 ka, and strengthened towards the present. Paleo-reconstructions of wind patterns, marine productivity and foraminifera assemblages were obtained using the IPSL-CM4 climate model coupled to the PISCES marine biogeochemical model and the FORAMCLIM ecophysiological model. These reconstructions are fully coherent with the marine core data. They confirm that the evolution of particulate export production and foraminifera assemblages at our two sites were directly linked with the strength of the upwelling. Model simulations at 9 ka and 6 ka BP show that the relative evolution between the two sites since the early Holocene can be explained by the weakening but also the southward shift of monsoon winds over the Arabian Sea during boreal summer.
English
Coverage:Geographic coordinates:
North:18.0305
West:57.3633East: 57.3700
South:7.0300

Quaternary geology; Arabian Peninsula; Arabian Sea; Asia; biochemistry; C-14; carbon; Cenozoic; chlorophyll; climate forcing; currents; Foraminifera; Globigerinacea; Globigerinidae; Globigerinoides; Globigerinoides bulloides; Holocene; India; Indian Ocean; Indian Peninsula; insolation; Invertebrata; isotopes; Leg 117; lower Holocene; marine environment; microfossils; monsoons; Ocean Drilling Program; ODP Site 723; Oman; organic compounds; paleocurrents; paleoenvironment; particulate materials; phytoplankton; pigments; plankton; porphyrins; productivity; Protista; Quaternary; radioactive isotopes; Rotaliina; salinity; tropical environment; upwelling; winds;

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