Tectonic evolution of segments of the Cordilleran (SE British Columbia) and Appalachian (Vermont) margins of the North American craton: A comparison
- Queen's Univ., Kingston, Ontario (Canada). Dept. of Geological Sciences
Both the eastern and western margins of North America record late Proterozoic/early Paleozoic rifting related to the development of the Iapetus and proto-Pacific oceans. Both margins were subsequently deformed when the adjacent ocean basis closed during the Paleozoic and Mesozoic eras, respectively. Detailed mapping projects in central Vermont and southeastern British Columbia provide an opportunity to compare and contrast the stratigraphic and structural evolution of the two margins, and to investigate similarities and differences in the tectonic processes. Lateral facies and thickness variations imply that the presently exposed basement acted as a crustal high'' during rifting and experienced little subsidence prior to the onset of passive margin sedimentation. The Purcell anticlinorium of southeastern British Columbia exposes a sequence of immature siliciclastic Upper Proterozoic rocks (Windermere Supergroup), up to several km thick, which unconformably overlie the Middle Proterozoic Belt Supergroup. Upper Proterozoic rocks are regionally unconformably overlain by a sequence of dominantly mature quartzites and overlying shallow water carbonate (Lower Cambrian Badshot Formation). Although this sequence is markedly similar to that observed in Vermont, there are several critical differences. Sedimentation in the adjacent basin to the west was punctuated by several episodes of mafic volcanisms and immature clastic influx from Late Proterozoic to post-Early Cambrian/pre-Mississippian time. The duration of active tectonism was clearly longer than can be accounted for by recent models of continental rifting. In both areas, the outboard edges of the crustal highs'' developed during rifting, as outlined by profound stratigraphic changes, correspond to profound structural/metamorphic contrasts developed during subsequent collapse of the margins.
- OSTI ID:
- 5639801
- Report Number(s):
- CONF-9303211-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:2; Conference: 28. annual Geological Society of America (GSA) Northeastern Section meeting, Burlington, VT (United States), 22-24 Mar 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BRITISH COLUMBIA
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
STRATIGRAPHY
GEOLOGIC HISTORY
VERMONT
APPALACHIAN MOUNTAINS
COMPARATIVE EVALUATIONS
MAPPING
OROGENESIS
PRECAMBRIAN ERA
RIFT ZONES
ROCKY MOUNTAINS
TECTONICS
CANADA
DEVELOPED COUNTRIES
EVALUATION
GEOLOGIC AGES
GEOLOGY
MOUNTAINS
NORTH AMERICA
USA
580000* - Geosciences