Abstract
The Monashee decollement, a crustal-scale shear zone in the hinterland (Omineca belt) of the southern Canadian Cordillera is interpreted as correlating with the sole thrust of the Rocky Mountain Foreland belt. LITHOPROBE seismic reflection data indicate that the shear zone is rooted in the lower crust beneath the Intermontane Superterrane. The decollement is exposed on the margins of the Monashee complex, an elongate domal culmination within the Omineca belt. This complex includes Early Proterozoic gneisses of North American basement. The hangingwall of the decollement consists of deformed and metamorphosed North American continental margin and oceanic accreted terranes of the Selkirk allochthon. Layered reflections observed in LITHOPROBE seismic reflection data correlate with sheared and transposed rocks in both the hangingwall and the footwall of the Monashee decollement; the decollement is imaged as reflections, cutoffs and correlatable reflection segments. Field relations, kinematics and geochronology indicate that the shear zone has experienced a complex history that included protracted easterly directed shear of hangingwall rocks and imbrication of basement rocks in its footwall. U-Pb zircon dating of syn- and post-kinematic leucogranites in the decollement zone demonstrates that the final stages of thrusting occurred in the Late Palaeocene. The cessation of thrusting and the onset of crustal extension in the southern Omineca belt correspond to the end of thrusting in the Foreland belt.
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References
Armstrong, R. L. 1982. Cordilleran metamorphic core complexes-from Arizona to southern Canada. Annual Reviews of Earth and Planetary Science, 10, 129–154.
Armstrong, R. L. 1988. Mesozoic and early Cenozoic magmatic evolution of the Canadian Cordillera. Geological Society of America Special Paper, 218, 55–91.
Armstrong, R. L., Taubeneck, W. H. & Hales, P. O. 1977. Rb-Sr and K-Ar geochronometry of Mesozoic granitic rocks and their Sr isotopic composition, Oregon, Washington, and Idaho. Geological Society of America Bulletin, 88, 397–411.
Bally, A. W., Gordy, P. L. & Stewart, G. A. 1966. Structure, seismic data, and orogenic evolution of southern Canadian Rockies. Bulletin of Canadian Petroleum Geology, 14, 337–381.
Berthe, D., Choukroune, P. & Jegouzo, P. 1979. Orthogneiss, mylonite and non-coaxial deformation of granites: the example of the South Amorican Shear Zone. Journal of Structural Geology, 1, 31–42.
Bosdachin, R. 1989. Structure, stratigraphy, and tectonothermal evolution of the central western flank of the Monashee complex, southeastern British Columbia. M.Sc. thesis, Carleton University (unpubl.).
Brown, R. L. 1980. Frenchman Cap dome, Shuswap complex, British Columbia: a progress report. In: Current Research, Part A. Geological Survey of Canada, Paper 80–1A, 47–51.
Brown, R. L. & Journeay, J. M. 1987. Tectonic denudation of the Shuswap metamorphic terrane of southeastern British Columbia. Geology, 15, 142–146.
Brown, R. L. & Read, P. B. 1983. Shuswap terrane of British Columbia: a Mesozoic ‘core complex’. Geology, 11, 164–168.
Brown, R. L., Journeay, J. M., Lane, L. S., Murphy, D. C. & Rees, C. J. 1986. Obduction, backfolding and piggyback thrusting in the metamorphic hinterland of the southeastern Canadian Cordillera Journal of Structural Geology, 8, 255–268.
Carr, S. D. 1986. The Valkyr shear zone and the Slocan Lake fault zone: Eocene structures that bound the Valhalla gneiss complex, southeastern British Columbia. M.Sc. thesis, Carleton University (unpubl.).
Carr, S. D. 1989. Implications of Early Eocene Ladybird granite in the Thor-Odin-Pinnacles area, southern British Columbia. In: Current Research, Part E. Geological Survey of Canada, Paper 89–1E, 69–77.
Carr, S. D. 1990. Late Cretaceous-early Tertiary tectonic evolution of the southern Omineca belt, Canadian Cordillera. Ph.D. thesis, Carleton University (unpubl.).
Carr, S. D. & Brown, R. L. 1990. Southern Cordilleran LITHOPROBE transect: evidence for crustal thickening and collapse of the Omineca belt, Valhalla complex to Okanagan Valley, British Columbia. Geological Association of Canada-Mineralogical Association of Canada, Annual Meeting, Program with Abstracts, 15, A22.
Carr, S. D., Parrish, R. & Brown, R. L. 1987. Eocene structural development of the Valhalla complex, southeastern British Columbia. Tectonics, 6, 175–196.
Clowes, R. M., Brandon, M. T., Green, A. G., Yorath, C. J., Sutherland Brown, A., Kanasewich, E. R. & Spencer, C. 1987. LITHOPROBE — southern Vancouver Island: Cenozoic subduction complex imaged by deep seismic reflections. Canadian Journal of Earth Sciences, 24, 31–51.
Coleman, V. J. 1987. A metamorphic and kinematic study of the Monashee decollement, southeastern British Columbia. B.Sc. thesis, Carleton University (unpubl.).
Coleman, V. J. 1989. The Cariboo duplex at the southern boundary of the Monashee complex, Shuswap terrane, southern B.C. In: Current Research, Part A. Geological Survey of Canada, Paper 89–1A, 89–93.
Coney, P. J. 1980. Cordilleran metamorphic core complexes: an overview. In: Crittenden, M. D., Jr., Coney, P. J. & Davis, G. H. (eds) Cordilleran Metamorphic Core Complexes. Geological Society of America Memoir, 153, 7–31.
Cook, F. A., Green, A. G., Simony, P. S., Price, R. A., Parrish, R., Milkereit, B., Gordy, P. L., Brown, R. L., Coflin, K. C. & Patenaude, C. 1987. LITHOPROBE southern Canadian Cordilleran transect: Rocky Mountain thrust belt to Valhalla gneiss complex. Geophysical Journal of the Royal Astronomical Society, 89, 91–98.
Cook, F. A., Green, A. G., Simony, P. S., Price, R. A., Parrish, R., Milkereit, B., Gordy, P. L., Brown, R. L., Coflin, K. C. & Patenaude, C. 1988. LITHOPROBE seismic reflection structure of the southeastern Canadian Cordillera: initial results. Tectonics, 7, 157–180.
Donelick, R. A. & Beaumont, C. 1990. Late Cretaceous-early Tertiary cooling of the Brazeau thrust sheet, Central Foothills, Alberta: implications for the timing of the end of Laramide thrusting in the region. Geological Association of Canada-MineralogicalAssociation of Canada, Annual Meeting, Program with Abstracts, 15, A34.
Duncan, I. J. 1984. Structural evolution of the Thor-Odin gneiss dome. Tectonophysics, 101, 87–130.
Eaton, D. W. S. & Cook, F. A. 1988. LITHOPROBE seismic reflection imaging of Rocky Mountain structures east of Canal Flats, British Columbia. Canadian Journal of Earth Sciences, 25, 1339–1348.
Evenchick, C. A., Parrish, R. R. & Gabrielse, H. 1984. Precambrian gneiss and Late Proterozoic sedimentation in north-central British Columbia. Geology, 12, 233–237.
Gabrielse, H. 1985. Major dextral transcurrent displacements along the Northern Rocky Mountain Trench and related lineaments in north-central British Columbia. Geological Society of America Bulletin, 96, 1–14.
Gabrielse, H. & Yorath, C. J. 1989. DNAG #4. The Cordilleran orogen in Canada. Geoscience Canada, 16, 67–83.
Hanmer, S. K. 1984. The potential use of planar and elliptical structures as indicators of strain regime and kinematics of tectonic flow. In: Current Research, Part B. Geological Survey of Canada, Paper 84–1B, 133–142.
Hanmer, S. K. 1986. Asymmetric pull-aparts and foliation fish as kinematic indicators. Journal of Structural Geology, 8, 111–122.
Harrap, R. 1990. Stratigraphy and structure of the Monashee terrane in the Mount English area, west of Revelstoke, B.C. M.Sc. thesis, Carleton University (unpubl.).
Hoy, T. & Godwin, C. 1.1988. Significance of a Cambrian date from galena lead-isotope data for the stratiform Cottonbelt deposit in the Monashee complex, southeastern British Columbia. Canadian Journal of Earth Sciences, 25, 1534–1541.
Johnson, B. J. 1988a. Progress report: stratigraphy and structure of the Shuswap metamorphic complex in the Hunters Range, eastern Shuswap Highland (82L). In: Geological Fieldwork, 1987. British Columbia Ministry of Energy, Mines and Petroleum Resources, Paper 1988–1, 55–58.
Johnson, B. J. 1989b. Geology of the west margin of the Shuswap terrane near Sicamous: implications for Tertiary extensional tectonics (82L, M). In: Geological Fieldwork, 1988. British Columbia Ministry of Energy, Mines and Petroleum Resources, Paper 1989–1, 49–54.
Johnson, B. J. 1989b. Structural style of crustal extension in a cross-section through the Shuswap complex, southeastern British Columbia. Geological Society of America, Abstracts with Programs, 21, 98.
Johnson, B. J. & Brown, R. L. 1990. Crustal structure of the Omineca belt adjacent to line 19 of LITHOPROBE southern Canadian Cordillera transect. Geological Association of Canada-Mineralogical Association of Canada, Annual Meeting, Program with Abstracts, 15, A66.
Journeay, J. M. 1986. Stratigraphy, internal strain and thermo-tectonic evolution of northern Frenchman Cap dome: an exhumed duplex structure, Omineca hinterland, S.E. Canadian Cordillera. Ph.D. thesis, Queen’s University (unpubl.).
Journeay, J. M. & Brown, R. L. 1986. Major tectonic boundaries of the Omineca belt in southern British Columbia: a progress report. In: Current Research, Part A. Geological Survey of Canada, Paper 86–1A.
Lane, L. S. 1984. Brittle deformation in the Columbia River fault zone near Revelstoke, southeastern British Columbia. Canadian Journal of Earth Sciences, 21, 584–598.
Lister, G. S. & Snoke, A. W. 1984. S-C mylonites. Journal of Structural Geology, 6, 617–638.
McDonough, M. R. & Simony, P. S. 1988. Structural evolution of basement gneisses and Hadrynian cover, Bulldog Creek area, Rocky Mountains, British Columbia. Canadian Journal of Earth Sciences, 25, 1687–1702.
Means, W. D. 1981. The concept of steady-state foliation. Tectonophysics, 78, 179–199.
Monger, J.W.H., Price, R. A. & Tempelman-Kluit, D. J. 1982. Tectonic accretion and the origin of the two major metamorphic and plutonic welts in the Canadian Cordillera. Geology, 10, 1261–1266.
Monger, J.W.H., (principal compiler), Woodsworth, G. J., Price, R. A., Clowes, R. N., Riddihough, R. P., Currie, R., Hoy, T., Preto, V. A. G., Simony, P. S., Snavely, P. D. & Yorath, C. J. 1986. Transect B2, southern Canadian Cordillera, North American continent-ocean transects. Decade of North American Geology Program, Geological Society of America.
Murphy, D. C. 1987. Suprastructure/infrastructure transition, east-central Cariboo Mountains, British Columbia: geometry, kinematics and tectonic implications. Journal of Structural Geology, 9, 13–30.
Parkinson, D. 1990. Age and isotopic character of basement gneisses in the southern Monashee complex, southeastern B.C. Geological Association of Canada — Mineralogical Association of Canada, Annual Meeting, Program with Abstracts, 15, A101.
Parrish, R. 1984. Slocan Lake fault: a low angle fault zone bounding the Valhalla gneiss complex, Nelson map area, southern British Columbia. In: Current Research, Part A. Geological Survey of Canada, Paper 84–1A, 323–330.
Parrish, R. R. & Ross, G. 1989. Precambrian basement in the southern Canadian Cordillera: the cratonic connection. LITHOPROBE Cordilleran Workshop Summary, 72–77.
Parrish, R. R. & Ross, G. 1990. Review of the Precambrian basement of the Cordillera. Geological Association of Canada-Mineralogical Association of Canada, Annual Meeting, Program with Abstracts, 15, A101.
Parrish, R. & Scammell, R. 1988. The age of the Mount Copeland syenite gneiss and its metamorphic zircons, Monashee complex, southeastern British Columbia. Geological Survey of Canada, Paper 88–2, 21–28.
Parrish, R. R. & Wheeler, J. O. 1983. U-Pb zircon age of the Kuskanax batholith, southeastern British Columbia. Canadian Journal of Earth Sciences, 20, 1751–1756.
Parrish, R. R., Carr, S. D. & Parkinson, D. L. 1988. Extensional tectonics of the southern Omineca belt, British Columbia and Washington. Tectonics, 7, 181–212.
Passchier, C. W. & Simpson, C. 1986. Porphyroclast systems as kinematic indicators. Journal of Structural Geology, 8, 831–843.
Platt, J. P. 1984. Secondary cleavages in ductile shear zones. Journal of Structural Geology, 6, 439–442.
Platt, J. P. & Vissers, R. L. M. 1980. Extensional structures in anisotropic rocks. Journal of Structural Geology, 2, 397–410.
Price, R. A. & Mountjoy, E. W. 1970. Geologic structure of the Canadian Rocky Mountains between Bow and Athabaska rivers — a progress report. Geological Association of Canada Special Paper, 6, 7–26.
Price, R. A, Monger, J. W. H. & Roddick, J. A. 1985. Cordilleran cross-section, Calgary to Vancouver. In: Tempelman-Kluit, D. J. (ed.) Field Guides to Geology and Mineral Deposits in the Southern Canadian Cordillera. Geological Society of America, Cordilleran Section Guidebook, Vancouver, British Columbia, 3–1 to 3–85.
Read, P. B. & Brown, R. L. 1981. Columbia River fault zone: southeastern margin of the Shuswap and Monashee complexes, southern British Columbia. Canadian Journal of Earth Sciences, 18, 1127–1145.
Read, P. B. & Wheeler, J. O. 1976. Geology of Lardeau west-half map area. Geological Survey of Canada, Open File Map 288.
Reesor, J. E. & Moore, J. M., Jr. 1971. Petrology and structure of Thor-Odin gneiss dome, Shuswap metamorphic complex, British Columbia. Geological Survey of Canada Bulletin 195.
Scammell, R.J. 1986. Stratigraphy, structure and metamorphism of the north flank of the Monashee complex, southeastern British Columbia: a record of the Proterozoic crustal thickening. M.Sc. thesis, Carleton University (unpubl.).
Simony, P. S., Ghent, E. D., Craw, D., Mitchell, W. & Robbins, D. B. 1980. Structural and metamorphic evolution of northeast flank of Shuswap complex, southern Canoe River area, British Columbia. In: Crittenden, M. D., Jr., Coney, P. J. & Davis, G. H. (eds) Cordilleran Metamorphic Core Complexes. Geological Society of America Memoir, 153, 445–461.
Simpson, C. & Schmid, S. M. 1983. An evaluation of criteria to deduce the sense of movement in sheared rocks. Geological Society of America Bulletin, 94, 1281–1288.
White, W. H., Burrows, S. E., Carreras, J., Shaw, N. D. & Humphreys, F. J. 1980. On mylonites in ductile shear zones. Journal of Structural Geology, 2, 175–187.
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Brown, R.L., Carr, S.D., Johnson, B.J., Coleman, V.J., Cook, F.A., Varsek, J.L. (1992). The Monashee decollement of the southern Canadian Cordillera: a crustal-scale shear zone linking the Rocky Mountain Foreland belt to lower crust beneath accreted terranes. In: McClay, K.R. (eds) Thrust Tectonics. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-3066-0_32
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