Regional acoustic imagery and detailed geophysical studies of northern Juan de Fuca Ridge

Conference · Tue Jul 01 04:00:00 EDT 1986 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:7148639

Davis, E E; Currie, R G; Villinger, H; Goodfellow, W D; Hussong, D M; Ryan, W B.F.; Hammond, S R

Acoustic image and high-resolution swath mapping studies have been conducted over the northern Juan de Fuca Ridge system from the central Juan de Fuca Ridge at lat. 46/sup 0/N to the triple junction of the ridge with the Queen Charlotte Islands continental margin at lat. 52/sup 0/N. Results of the surveys have been published as 1:250,000 compilations and 1:50,000 detailed sheets of acoustic image mosaics and 10-m contour bathymetric maps. Of particular interest is the information that influences processes of hydrothermal mineralization. In general, little direct information is present in the imagery; only the exact location and nature of the currently active rift axis are seen. However, this information is important, since the along-strike variations in crestal morphology, the recency and level of volcanic activity, and the degree of post-volcanic extension must be known in order to understand any hydrothermal system observed along the axis. An exceptional case has been studied in detail at the northern Juan de Fuca Ridge, lat. 49/sup 0/30'N, where Pleistocene turbidite sediments bury the axial valley, and structures suspected to be of hydrothermal origin were observed in the acoustic imagery over faults that bound the valley. Subsequent higher resolution acoustic imagery, seismic reflection profiling, and heat-flow studies indicated that the features were of hydrothermal origin. A 2.5-m piston core sample of massive sulfides from one of the structures confirmed this speculation. The setting in which these relatively large (500-m diameter, 60-m surficial relief, 350-m relief above basement) structures occur is remarkably similar to that where large sediment-hosted sulfide deposits are found on land, although they do not know what the bulk composition of the structures is, and thus whether the analogy is complete.

• Research Organization: Pacific Geoscience Centre, Sidney, British Columbia
• OSTI ID: 7148639
• Report Number(s): CONF-8608105-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 70:7
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
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& Exploration
58 GEOSCIENCES
580200 -- Geophysics-- (-1989)
ACOUSTIC MEASUREMENTS
ENERGY SYSTEMS
EXPLORATION
GEOPHYSICAL SURVEYS
GEOTHERMAL SYSTEMS
HYDROTHERMAL SYSTEMS
MAPPING
PACIFIC OCEAN
SEAS
SEISMIC SURVEYS
SURFACE WATERS
SURVEYS
VOLCANISM