Dave Goldberg, Gilles Guerin
During Ocean Drilling Program (ODP) Leg 204, a total of nine sites were drilled through the gas hydrate stability zone on the southern part of Hydrate Ridge on the Cascadia accretionary margin, offshore Oregon. For further information regarding gas hydrates and the background geological setting see the Leg 204 Preliminary Report. The first part of Leg 204 was dedicated entirely to logging while drilling (LWD) to identify potential gas hydrate bearing intervals prior to coring. The data were of excellent quality, thus allowing optimization of the use of time-consuming special tools to measure in situ temperature and pressure and to retrieve cores at in situ pressure. The leg also included an extensive wireline logging program and a two-ship seismic program with the R/V Maurice Ewing to acquire offset and walkaway vertical seismic profiles (VSP).