Although the occurrence of gas hydrate is perceived to be extensive in sediments of the Blake Ridge, recovery proved to be difficult during the coring efforts of the Ocean Drilling Program (ODP) Leg 164. With the exception of Site 996, an area of methane gas venting, gas hydrate recovery from core material was limited to only three cores. To understand the occurrence of gas hydrate in this environment, a collection of direct and indirect measurements of sediments was made.
Figure 1 (PDF oversized foldout, this volume) summarizes some important measurements and observations pertaining to gas hydrate occurrence at Sites 994, 995, and 997. These sites comprise a transect of holes that penetrate below the base of gas hydrate stability within the same stratigraphic interval over a relatively short distance (9.6 km). A bottom-simulating reflection (BSR) is not observed at Site 994, a modest BSR occurs at Site 995, and a strong BSR is seen at Site 997. An account of the seismic line, USGS 95-1, can be found in Dillon et al. (1996).
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).
2U.S. Geological Survey, 345
Middlefield Rd., MS-999, Menlo Park, CA 94025, U.S.A. tlorenson@usgs.gov
3Shipboard
Scientific Party is given in the Preliminary
Pages.
Date of
initial receipt: 6 November 1998
Date of acceptance: 24 May 1999
Ms 164SR-248