HR: 08:15h
AN: OS11C-02    [Abstracts]
TI: Stratigraphy, Sedimentology, and Depositional History of Gas Hydrate Bearing Sediments Along the Eastern Continental Margin of India and in the Andaman Accretionary Wedge: Results from NGHP Expedition 01
AU: * Johnson, J E
EM: joel.johnson@unh.edu
AF: University of New Hampshire, Department of Earth Sciences, 56 College Rd. James Hall 121, Durham, NH 03824, United States
AU: Giosan, L
EM: lgiosan@whoi.edu
AF: Woods Hole Oceanographic Institution, Clark 257, MS#22, Woods Hole, MA 02543, United States
AU: Rose, K
EM: kelly.rose@netl.doe.gov
AF: U.S. Department of Energy, National Energy Technology Laboratory, 3610 Collins Ferry Rd, Morgantown, WV 26507, United States
AU: Fraschetti, J
EM: escirocks@gmail.com
AF: University of New Hampshire, Department of Earth Sciences, 56 College Rd. James Hall 121, Durham, NH 03824, United States
AU: NGHP Expedition 1, S
AB: An international ocean drilling effort led by the Indian National Gas Hydrate Research Program (NGHP) and the U.S. Geological Survey to study gas hydrates along the Indian continental margins was completed during the summer of 2006. Drill and core sites documented the presence of gas hydrate along the eastern continental margin of India in the Krishna-Godavari (K-G) and Mahanadi basins, and in the Andaman wedge near Little Andaman Island. 2-D and 3-D seismic data provide the high-resolution structural and stratigraphic context for each of the drill sites. These data combined with detailed lithologic descriptions, multi-sensor core logger (MSCL) measurements, and logging while drilling (LWD) data characterize the sedimentology of the recovered cores and of the in situ stratigraphy at each site. In the K-G basin slope environment, sedimentological description and interpretation of the cores collected from seven sites (up to 300 mbsf) reveals a Quaternary history of sedimentation dominated by dark grey to black colored nannofossil bearing to rich clay and silty clay deposition, likely sourced from the nearby Krishna and Godavari Rivers. Silt to fine sand turbidites (1-5 cm thick) also occur throughout the section as well as visible terrestrial organic material. Foraminifera and coccoliths occur throughout the records but are highly diluted by the terrigenous constituents. Authigenic carbonates, present in fine grained bands and as micronodules (less than 1 cm) to large nodules (greater than 5 cm) are particularly abundant throughout most of recovered stratigraphy and are consistent with the recovery and presence of gas hydrate and other indicators of gas hydrate throughout this region. Sediments recovered from the two sites drilled in the Mahanadi basin to the north are biogenic-rich (foraminifera, coccoliths, diatoms, and radiolaria) clays to oozes and void of turbidites. A volcanic ash bed near the top of the section and volcanic glass bearing intervals deeper in the section are also present. Based on initial biostratigraphy, the age of the recovered sediments spans Late Miocene to recent at these sites. Authigenic carbonates are rare throughout the section and there was less gas hydrate recovered at these sites. At the single site drilled in the Andaman wedge, a long record (nearly 700 m) of carbonate and biosiliceous clays and oozes, punctuated by abundant volcanic ashes, was recovered. Initial biostratigraphy here also suggests a late Miocene to recent record. An extremely deep BSR (610 mbsf) indicates a thick zone of potential gas hydrate stability at this site; gas hydrate was recovered throughout this interval and often associated with volcanic ash beds. Post-cruise XRD, XRF, organic and inorganic carbon, and other geochemical measurements will help to further characterize the stratigraphy at all of these sites.
DE: 1051 Sedimentary geochemistry
DE: 3002 Continental shelf and slope processes (4219)
DE: 3022 Marine sediments: processes and transport
DE: 3036 Ocean drilling
DE: 4863 Sedimentation (1861)
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting