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Mulitcorer being lowered into Indonesian waters. Once allowed to settle gently into the sediments, the clear multicorer tubes fill with sediment. This is the best way to recover the undisturbed recent sediments

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A filled multicorer tube.

Collaborative Research: Variability of the Indonesian Throughflow During the Holocene

Yair Rosenthal (Rutgers University) Brad Linsley (University of NY at Albany)

The Indonesian Throughflow (ITF) refers to the transfer of upper ocean waters from the Pacific to the Indian Ocean through the Indonesian Seas. Variations in the ITF affect the properties, and climate of both the Indian and Pacific Oceans, and may also feedback and influence ENSO. It is not known whether the ITF has varied in the past, and if so, the effect of these variations on regional and global climate.

In 2003, we collected sediment cores from the Indonesian Seas in order to reconstruct past changes in the Indonesian Throughflow (ITF) and climate of the region. We collaborated with Indonesian scientists and used the R/V Baruna Jaya VIII, an Indonesian vessel. WHOI's Jim Broda designed a coring rig, capable of taking multicores and gravity cores for the vessel.

As most of the ITF occurs in the thermocline, most of the cores we collected were from thermocline depths. Work in our labs confirms that many of the cores we collected have high accumulation rates (even in excess of 100cm/kyr), and many have modern core-tops. We are using the chemistry of benthic foraminifera in thermocline depth cores to reconstruct changes in the ITF at decadal resolution during the Holocene. We are also using the chemistry of planktonic foraminifera to reconstruct surface hydrography, and by measuring the chemistry of thermocline dwellers, a second measure of thermocline depth and properties.

MIT/WHOI Joint Program student Fern Gibbons is taking the lead on the multiple species planktonic work.

MIT/WHOI Joint Program student James Saenz is characterizing organic biomarkers in core-top sediment and has generated downcore record for one Holocene core. The records show orbital scale trends. He is currently trying to distinguish between two interpretations for the signals: an interpretation that involves changes in ITF transport of different vegetation types and a local vegetation signal

University of NY at Albany student Samantha Logan is generating downcore records in Kau Bay, a silled basin. Her preliminary results suggest a correlation between ventilation of the basin and ENSO.

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