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ABSTRACT: The Geology and Petroleum Potential of the Queen Charlotte Basin, Pacific Continental Margin, Canada

J. R. Dietrich, R. Higgs, K. Rohr

The Queen Charlotte basin is a 40000 km2 late Paleogene-Neogene basin underlying the Queen Charlotte Islands, Hecate Strait, and Queen Charlotte Sound region of the Canadian Pacific continental margin. The basin formed during Eocene to Pliocene extension along and adjacent to a transform segment of the Pacific-North American plate boundary. Oblique subduction along the plate boundary in the late Cenozoic resulted in uplift and folding of portions of the northern half of the basin. In detail, the basin consists of numerous, variably oriented half-grabens and subbasins separated and underlain by complexly structured Mesozoic rocks of the Wranellia terrane. Most of the offshore subbasins contain clastic sediments in excess of 3000 m thick, and strata as thick as 6 00 m are known to occur in the deepest depocenters. The older (pre-Pliocene) portions of the basin locally contain volcanics, often interbedded with clastics. Potential hydrocarbon reservoirs within the basin include alluvial-fan, fan-delta, and tidal-shelf sandstones. Potential hydrocarbon source rocks include Upper Triassic-Lower Jurassic shales and limestones locally preserved below the basin, and Tertiary shales within the deeper portions of the basin fill. Possible hydrocarbon traps include folds, rollover anticlines, basement fault blocks, and a variety of combined structural-stratigraphic traps. The Queen Charlotte basin is considered to be one of the most prospective areas for significant hydrocarbon resources along the northeast Pacific margin.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990