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Bengal Fan IODP Expedition 354

IODP Expedition 354 - PI : Christian France-Lanord

Participant CRPG : Albert Galy

Expedition general informations

Dates : 29 January-31 March 2015
Ports : Singapore to Colombo, Sri Lanka
Co-chief Scientists : Christian France-Lanord & Volkhard Spieß
Staff Scientist : Adam Klaus
Scientific Prospectus

Summary

The Bengal Fan Expedition is based on IODP Proposal 552-Full3 and will drill a transect of sites across the middle Bengal Fan to obtain a Neogene and late Paleogene record of Himalayan orogeny and climate. The objectives are to investigate interactions among the growth of the Himalaya and Tibet, the development of the Asian monsoon, and processes affecting the carbon cycle and global climate.

Figure 1. Map of the Himalayan erosion system showing the position of existing DSDP and ODP sites documenting the Bengal and Indus Fans or the monsoon history. Red box = location of Expedition 354 Middle Bengal Fan (MBF) drill site transect at 8°N. Bengal Fan sediment isopachs (blue lines ; in kilometers) are simplified from Curray et al. (2003) and represent the total sedimentary and meta-sedimentary rocks above the oceanic basalt as interpreted from seismic reflection and refraction data.

One deep penetration site (MBF 1) aims to document the early stages of Himalayan erosion, the India-Eurasia collision, and the development of the Himalaya and Tibet. The transect will constrain the Neogene development of the Asian monsoon, its impact on sediment supply and flux, and allow quantitative studies of the interrelations of climate change and sediment accumulation. Sediments obtained will document (1) uplift history through erosional flux and deposition patterns and detailed geochronology of minerals, (2) Himalayan evolution from isotopic tracing of particle origin and age, and (3) environmental and climate conditions through sediment granulometry, mineralogy and geochemistry, organic matter composition and oxygen isotopes of microfossils.

Figure 2. Top : Seismic Profile GeoB097-020/027 showing the positions of Expedition 354 drill sites in relation to regional fan architecture. The tops of the Pliocene and Miocene, as well as the 10 Ma horizon, are traced through the profile based on results from DSDP Site 218 (Moore et al., 1974). The distinct unconformity in the east that is penetrated only by the deepest part of proposed site MBF-3A is inferred to represent the Eocene onset of fan deposition. Bottom : Interpreted line drawing of Profile GeoB97-020/027 showing the later stage channel-levee systems, regional unconformities and faults. Modified from Schwenk and Spieß (2009). TWT = two-way traveltime, VE = vertical exaggeration. Horizontal scale = common midpoint (CMP) numbers, CMP distance = 20 m. Naming of channels follows Curray et al., 2003.

References

Curray, J.R., Emmel, F.J., and Moore, D.G., 2003. The Bengal Fan : morphology, geometry, stratigraphy, history and processes. Mar. Pet. Geol., 19(10):1191–1223. doi:10.1016/ S0264-8172(03)00035-7

Schwenk, T., and Spieß, V., 2009. Architecture and stratigraphy of the Bengal Fan as response to tectonic and climate revealed from high-resolution seismic data. In Kneller, B.C., Mar- tinsen, O.J., and McCaffrey, B. (Eds.), External Controls on Deep-Water Depositional Systems. Spec. Publ.—SEPM (Soc. Sediment. Geol.), 92:107–131.

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