Since being first discovered in the Blake-Bahama region of the west Atlantic in the 1970s (Hollister, Ewing, et al., 1972), submarine gas hydrates have been identified in the continental margin worldwide. Ocean Drilling Program (ODP) Leg 164 was the first drilling designated to study the occurrence and distribution of natural gas hydrates in Blake Ridge where a well developed, distinct BSR (Bottom Simulating Reflector) has been identified (Paull, Matsumoto, Wallace, et al., 1996).
It has been reported there is a prominent discrepancy between the BSR and the base of gas hydrate stability (Paull, Matsumoto, Wallace, et al., 1996; Ruppel, 1997), though theoretically they should be at the same depth. Natural gas hydrate in marine sediments coexists with sediment particles, so detailed delineation of sediment geochemistry will be of benefit to solve this apparent discrepancy. The main objectives of this study are to supply background data of the major chemical compositions of sediments from a hydrated sediment section.
1Paull,
C.K., Matsumoto, R., Wallace, P.J., and Dillon, W.P. (Eds.), 2000. Proc. ODP,
Sci. Results, 164: College Station, TX (Ocean Drilling Program).
2Geological
Institute, University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan.
3Present address:
Technology Research Center, Japan National Oil Corporation, 1-2-2, Hamada,
Mihama-ku, Chiba 261-0025, Japan. hailong@jnoc.go.jp
4Geological
Survey of Japan, Tsukuba 305, Japan.
Date of
initial receipt: 12 May 1998
Date of acceptance: 4 December 1998
Ms 164SR-224