The rise and fall of a cratonic arch: A regional seismic perspective on the Peace River
The Peace River Arch (PRA) is a roughly east-west striking cratonic element of the Western Canada Sedimentary Basin that cuts across the trend of underlying Paleoproterozoic basement tectonic domains at a high angle. This region preserves several distinct phases of tectonic evolution during the Phan...
| Main Authors: | , , |
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| Format: | Text |
| Language: | English |
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1999
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.627.2856 http://www.lithoprobe.ca/transectsWebSites/ab/bulletins/346_361_eaton.pdf |
| Summary: | The Peace River Arch (PRA) is a roughly east-west striking cratonic element of the Western Canada Sedimentary Basin that cuts across the trend of underlying Paleoproterozoic basement tectonic domains at a high angle. This region preserves several distinct phases of tectonic evolution during the Phanerozoic that included an early- to mid-Paleozoic arch phase and a Carboniferous-to-Triassic embayment phase. In 1994, Lithoprobe recorded the first public-domain regional seismic-reflection survey across the PRA, a 627-km transect called the Peace River Arch Industry Seismic Experiment (PRAISE). This survey combined typical industry acquisition parameters with large shot-receiver offsets (>6 km) and long recording times (18 s) to image both bedding-scale and crustal-scale tectonic elements. The regional extent, continuity and long recording times of the PRAISE seismic profiles are exploited here to examine various aspects of basement and basin evolution from Middle Cambrian to Triassic time. Key findings of this investigation are: (1) a greater than expected role for onlap in the overall northward thinning of the Cambro-Ordovician sedimentary wedge onto the southern flank of the PRA; (2) evidence for a previously unrecognized pre-Middle Devonian deformational event that produced broad, low-relief folds in Cambro-Ordovician rocks; (3) seismic evidence that some Granite Wash deposits formed within Upper Devonian grabens that may have been precursors to Carboniferous extensional faults; (4) a spatial overlap of the southeastern arm of the Fort St. John graben with a strong, east-dipping reflection fabric devel- |
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