Interrelationship of fluid venting and structural evolution: Alvin observations from the frontal accretionary prism, Oregon

Journal Article · Sun Jun 10 04:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JB095iB06p08795· OSTI ID:5073581

Moore, J C; Orange, D ^[1]; Kulm, L D ^[2]

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1. Univ. of California, Santa Cruz (United States)
2. Oregon State Univ., Corvallis (United States)

Seismic reflection and Sea Beam bathymetric data plus submarine geological measurements define a ramp anticline at the deformatoin front of the central Oregon subduction zone. At its northern termination the ramp anticline is deeply incised by a large 500-m-deep submarine canyon and cut by a probable backthrust. To the south along the strike of the fold, a smaller submarine canyon shallowly erodes the anticline, and backthrusting is not apparent in the submersible observations. Two Alvin dives along a transect through the southern canyon show active fluid vents demarked by biological communities at the frontal thrust and at the breached crest of the anticline. Along a northern transect, encompassing the large submarine canyon, 10 Alvin dives indicated no venting on the formal thrust, limited venting in the canyon, but numerous biological communities along a scarp interpreted as the surface trace of the backthrust. These observations suggest a scenario of vent and structural-geomorphic development consisting of (1) frontal thrust faulting and associated venting, facilitated by high fluid pressure; (2) erosion of the oversteepened seaward flank of the ramp anticline assisted by seepage forces and leading to fluid flow out of stratigraphically controlled conduits in the limbs of the overthrust deposits; (3) locking of the frontal thrust due to dewatering or a local decrease in wedge taper associated with development of the large canyon, leading to failure along the backthrust; and (4) redirection of fluid flow by the backthrust. Thus, within {le}0.3 m.y., deformation of the relatively permeable sediments of the Oregon margin results in stratigraphically controlled flow being partially captured by faults.

• OSTI ID: 5073581
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:B6; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ANTICLINES
AQUATIC ORGANISMS
BENTHOS
CONTINENTAL MARGIN
DEFORMATION
DEVELOPED COUNTRIES
ENERGY SYSTEMS
EROSION
FEDERAL REGION X
FLUIDS
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
GEOMORPHOLOGY
GEOPHYSICAL SURVEYS
GEOTHERMAL SYSTEMS
HABITAT
HYDROTHERMAL SYSTEMS
NORTH AMERICA
OPTICAL PROPERTIES
OREGON
PHYSICAL PROPERTIES
REFLECTIVITY
RESERVOIR FLUIDS
RESERVOIR PRESSURE
SEEPS
SEISMIC SURVEYS
SUBDUCTION ZONES
SURFACE PROPERTIES
SURVEYS
TECTONICS
USA
VENTS