Abstract
Gassy sediments are detectable acoustically in subbottom profiles of Canada's Fraser Delta slope and prodelta areas. Interstitial gas is typically represented by zones of acoustic turbidity on high-resolution seismic profiles and by gas brightening on air-gun profiles. The top of the acoustically turbid zone is generally highest within the sediment column closest to the river mouths and lies within 10 ms (two-way travel time) of the sea floor in a nearly continuous area that covers over 530 km2. Most of the gas is believed to be biogenic in origin, although thermogenic gas derived from underlying Tertiary sedimentary rocks may be present in places.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Anderson AL, Bryant WR (1990) Gassy sediment occurrence and properties: northern Gulf of Mexico. Geo-Marine Letters 10: 209–220
Anderson AL, Hampton LD (1980) Acoustics of gas-bearing sediment. Journal of the Acoustical Society of America 67:1865–1903
Bustin RM (1990) Stratigraphy, sedimentology, and petroleum source rock potential of the Georgia Basin, southwest British Columbia and northwest Washington State. Geological Survey of Canada Paper 90-1F:103–108
Hamilton TS (1991) Seismic stratigraphy of unconsolidated sediments in the Central Strait of Georgia: Hornby Island to Roberts Bank. Geological Survey of Canada, Open File 2350
Hart BS (1992) Side-scan sonar observations of Point Grey dump site, Strait of Georgia, British Columbia. Geological Survey of Canada Paper 92-1A:55–61
Hart BS, Prior DB, Hamilton TS, Barrie JV, Currie RG (1992) Patterns and styles of sedimentation, erosion and failure, Fraser Delta slope, British Columbia. In: Proceedings, Geohazards '92. Canadian Geotechnical Society, 365–372
Hovland M, Judd AG (1988) Seabed pockmarks and seepages. Graham and Trotman, Boston. 293 pp
Luternauer JL, Finn WDL (1983) Stability of the Fraser River delta front. Canadian Geotechnical Journal 20: 603–616
Macdonald RW, Macdonald DM, O'Brien MC, Gobeil C (1991) Accumulation of heavy metals (Pb, Zn, Cu, Cd), carbon and nitrogen in sediments from Strait of Georgia, B.C., Canada. Marine Chemistry 34: 109–135
Mathews WH, Shepard FP (1962) Sedimentation of Fraser Delta, British Columbia. American Association of Petroleum Geologists Bulletin 46: 1416–1443
Milliman JD (1980) Sedimentation in the Fraser River and its estuary, southwestern British Columbia (Canada). Estuarine and Coastal Marine Science 10: 609–633
Nelson CS, Lawrence MF (1984) Methane-derived high-Mg calcite submarine cement in Holocene nodules from the Fraser Delta, British Columbia, Canada. Sedimentology 31: 645–654
Pharo CH (1972) Sediments of the central and southern Strait of Georgia, British Columbia. Unpublished PhD thesis. University of British Columbia, Vancouver. 290 pp
Prior DB, Coleman JM (1984) Submarine slope instability. In: Brunsden D, Prior DB (Eds), Slope Instability. Wiley & Sons, New York. pp 419–455
Rice DD, Claypool GE (1981) Generation, accumulation, and resource potential of biogenic gas. American Association of Petroleum Geologists Bulletin 65: 5–25
Schubel JR (1974) Gas bubbles and the acoustically impenetrable, or turbid, character of some estuarine sediments. In: Kaplan IR (Ed), Natural Gases in Marine Sediments. Plenum Press, New York. pp 275–298
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Hart, B.S., Hamilton, T.S. High-resolution acoustic mapping of shallow gas in unconsolidated sediments beneath the strait of Georgia, British Columbia. Geo-Marine Letters 13, 49–55 (1993). https://doi.org/10.1007/BF01204392
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF01204392