During Ocean Drilling Program Leg 204, 80 in situ measurements of
subseafloor temperature were made; 68 of these showed good frictional
pulses on insertion and extraction from the seafloor and were used to
constrain the subsurface temperature. Considering uncertainties from
various sources, uncertainties in the in situ temperatures are estimated...
Ocean Drilling Program (ODP) Leg 204 to Hydrate Ridge, located on the continental slope offshore Oregon (USA), was the first drilling expedition dedicated to understanding gas hydrate processes in accretionary complexes and provided a testbed for a number of different techniques for estimating the gas hydrate content of sediments. It...
Log and core data document gas saturations as high as
90% in a coarse-grained turbidite sequence beneath the gas
hydrate stability zone (GHSZ) at south Hydrate Ridge, in the
Cascadia accretionary complex. The geometry of this gas-saturated
bed is defined by a strong, negative-polarity
reflection in 3D seismic data. Because...
Three successful vertical seismic profiles (VSPs) were acquired during
Ocean Drilling Program (ODP) Leg 204 at South Hydrate Ridge. The
data confirm earlier results from ocean bottom seismometer data and
analysis of moveout from common midpoint reflection data that the
average velocity between the seafloor and the bottom-simulating reflector
(BSR)...
High‐resolution three‐dimensional (3‐D) seismic reflection data acquired on the R/V Thomas G. Thompson in 2000 reveal a pair of bottom simulating reflections (BSRs) across a broad region of southern Hydrate Ridge, offshore Oregon. The primary BSR (BSRp) is a regionally extensive reflection that lies 120–150 m below seafloor and exhibits...
Drilling in the Cascadia accretionary complex enable us to evaluate the contribution of dehydration reactions and gas hydrate dissociation to pore water freshening. The observed freshening with depth and distance from the prism toe is consistent with enhanced conversion of smectite to illite, driven by increase in temperature and age...
Submersible investigations of the Cascadia accretionary
complex have identified localized venting of methane gas
bubbles in association with gas hydrate occurrence. Acoustic
profiles of these bubble plumes in the water column in the
vicinity of Hydrate Ridge offshore Oregon provide new
constraints on the spatial distribution of these gas vents...
Research on cetacean foraging ecology is central to our understanding of their spatial and behavioral ecology. Yet, functional mechanisms by which cetaceans detect prey across different scales remain unclear. Here, I postulate that cetaceans utilize a scale-dependent, multimodal sensory system to assess and increase prey encounters. I review the literature...
This paper presents a seismic sequence and structural analysis of a high-resolution three-dimensional seismic reflection survey that was acquired in June 2000 in preparation for Ocean Drilling Program (ODP) Leg 204. The seismic data were correlated with coring and logging results from nine sites drilled in 2002 during Leg 204....
The Vizcaino block is an anomalously shallow region of the western U.S continental margin located southwest of the Mendocino triple junction. It originated as part of the accretionary prism of the North America plate and was transferred to the Pacific plate in the Miocene as the Pacific-North America plate boundary...