Tectonic model for Eocene Formation of the Columbia basin
- F and F GeoResource Associates, Inc., Bend, OR (USA)
- Image Exploration, Minneapolis, MN (USA)
Evidence suggests that a major sedimentary basin underlies the Columbia plateau in Oregon and Washington; however, the Miocene Columbia River Basalts conceal critical structural relationships between adjacent exotic terranes. To date, no interpretations have been published that adequately address the three related questions of the architecture, age, and mechanism of formation of the Columbia basin. The authors interpret residual gravity and aerial photographic data to show, within the basin, a pattern of deep fault architecture consistent with northwest-southeast-oriented rifting. Paleotectonic reconstructions for the Pacific Northwest suggest that rifting may have begun during the Cretaceous, as interpreted previously, but stratigraphic, geophysical and well data point to an early Eocene age for initiation of dramatic rifting and basin subsidence resulting from oblique subduction of the Farallon plate. Their tectonic model for Eocene formation of rift basins underlying the Columbia River Basalt addresses important, previously unanswered questions regarding the tectonics of the Pacific Northwest and rationally relates tectonics and sedimentation over the full extent of the basin from north-central Washington to north-central Oregon. The rifting event(s) they propose explain that the formation of the Columbia basin is consistent in timing and geometry with tectonic events in areas adjacent to the Columbia basin, and thus is but a part of a much larger picture of dramatic extension affecting the entire Pacific Northwest in the Eocene.
- OSTI ID:
- 7061161
- Report Number(s):
- CONF-900605-; CODEN: AABUD
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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