Site U1443: Expedition 353

Abstract

International Ocean Discovery Program (IODP) Site U1443 is located ~100 m southeast of Ocean Drilling Program (ODP) Leg 121 Site 758 on the crest of the Ninetyeast Ridge and is a redrill of Site 758. The Ninetyeast Ridge represents the trace of the Kerguelen/Ninetyeast hotspot prior to middle Eocene rifting. As a result of northward movement, Site U1443 moved from temperate southern latitudes during the Campanian, to ~5°S near the Oligocene/Miocene boundary, and to its present location of 5°N in the southernmost Bay of Bengal. The site has been within 10° of the Equator for the past 35 My. One important paleoclimatic goal of Site U1443 was to recover sediment successions that would allow precise timing of onset and phases of intensification and weakening of the Indian monsoon system. In particular, the timing of the Miocene intensification of the Indian monsoon is still unresolved; suggestions for the initial intensification range between ~7–8, ~15, and ~22 Ma, and indications of an active monsoon have been suggested for as early as ~45 Ma. Proxy records for river discharge are presently of insufficient time resolution to document the relation between global climate and the Indian monsoon throughout the Neogene. The complete Neogene sediment archive at Site U1443 will make such reconstructions possible.