The role of the Shuswap Metamorphic Complex in Cordilleran tectonism: a review

1984 ◽  
Vol 21 (10) ◽  
pp. 1171-1193 ◽  
Author(s):  
Andrew V. Okulitch
Keyword(s):  
Late Paleozoic ◽  
Metamorphic Complex ◽  
Late Mesozoic ◽  
Magmatic Arc ◽  
Tectonic History ◽  
Laramide Orogeny ◽  
Kootenay Lake ◽  
Shuswap Metamorphic Complex ◽  
Transitional Crust ◽  
Two Stages

The Shuswap Metamorphic Complex consists of three parts, each with unique stratigraphy and orogenic evolution, separated by major faults of diverse nature and having in common only a post-late Mesozoic tectonic history. The first part, the Monashee Complex, is a possible extension of the Precambrian Shield that contains limited evidence of Mesozoic orogenesis and that was rapidly uplifted during the Cretaceous to Paleogene. The Monashee Décollement, a warped mylonite zone interpreted as a regional thrust fault active through the Middle Jurassic, separates this complex from the second part, which contains rocks correlative with Hadrynian to late Paleozoic strata of the pericratonic prism. The third part, the Okanagan Complex, straddling the 49th Parallel from the Okanagan Valley to Kootenay Lake, contains the probable exhumed roots of a Mesozoic magmatic arc built upon possible North American continental and transitional crust and includes late Paleozoic and early Mesozoic suspect terranes.The Columbian Orogen formed during westward drift of the craton into a continent of accreted elements. Response of the craton, attenuated during at least two episodes of Proterozoic rifting, and its overlying sedimentary prism to underthrusting from the east and simultaneous collision with an accreting collage from the west took place in two stages. First, attenuated crust was telescoped and thickened to its approximate original configuration while westernmost parts of the bordering prism were deformed and metamorphosed (the Jura-Cretaceous Columbian Orogeny that affected the Okanagan Complex and strata above the Monashee Décollement). Second, the thickened crust, the deformed prism, and platformal strata were thrust eastward (the Late Cretaceous – Paleocene Laramide Orogeny that formed the Rocky Mountains Thrust Belt). Waning convergent tectonism led to ascendancy of crustal extension (primarily in the Okanagan Complex) and final uplift of cratonic massifs.

Barrovian-type metamorphism in the western domain of the Cordillera Darwin Metamorphic Complex, Fuegian Andes

2021 ◽  
Author(s):  
Mauricio Calderon ◽  
Catalina Zúñiga ◽  
Francisco Hervé ◽  
Thomas Theye ◽  
Gonzalo Galaz ◽  
...  
Keyword(s):  
Geothermal Gradient ◽  
White Mica ◽  
Burial Depth ◽  
Metamorphic Complex ◽  
Constant Composition ◽  
Magmatic Arc ◽  
Garnet Core ◽  
Late Generation ◽  
Si Content ◽  
Two Stages

<p>The Cordillera de Darwin Metamorphic Complex (CDMC) comprise metamorphosed supracrustal rocks and metaplutonic suites which records a unique tectonic evolution among the metamorphic complexes of the southernmost Andes. The pressure (P) and temperature (T) conditions determined in garnet-bearing schists in the Central Domain of the CDMC indicate a clockwise P-T path of metamorphism reaching burial depth as high as 12 kbar at ca. 620°C. This metamorphic event has been related to the closure of a marginal back-arc basin (Rocas Verdes Basin) and collision of an ensialic magmatic arc with the continent in the late Cretaceous. We focus on garnet-biotite schists intercalated within a huge block consisting of repeated sequences of metabasalts and amphibolites (Rocas Verdes Ophiolites), located in the Western Domain of the CDMC, at Seno Martínez. The chemical zonation of small garnet porphyroblasts (diameter of ca. 300 um) record two stages of metamorphism. Garnet is almost almandine in composition with lesser amounts of Ca, Mn and Mg.  The concentric zonation is characterized by relatively lower contents of Fe-Mg and higher contents of Ca-Mn in the core. Garnet bear tiny inclusions of clinozoisite, which is also present as isolated grains in the foliated matrix. Laths of biotite define the main foliation and have a nearly constant composition characterized by X<sub>Fe</sub> of ca. 0.6. Two generations of phengitic white mica are identified on basis of Si content (a.pf.u.) varying between 3.20-3.30 (early generation) and of ca. 3.15 (late generation). To reconstruct the P-T conditions of metamorphism through thermodynamic modeling using the Perple_X software package, the bulk rock and mineral composition were considered. Using compositional isopleths of X<sub>Fe</sub>, X<sub>Mg</sub>, X<sub>Ca</sub> and X<sub>Mn</sub> in zoned garnet, Si content in white mica and X<sub>Fe</sub> in biotite allow the constrain two stages of metamorphism (M1 and M2). The P-T conditions of M1, represented by the composition of the garnet core, are restricted to ca. 8 kbar and 400°C. M2 is restricted to ca. 7.5 kbar at 480°C, determined with the composition of the garnet rim, X<sub>Fe</sub> in biotite and Si content in late phengitic white mica. Our preliminary results indicate that ophiolitic rocks and interleaved garnet-bearing schists were tectonically buried and metamorphosed in a relatively hot subduction interface characterized by a geothermal gradient of ca. 16°C/km, prior to the collision of the ensialic magmatic arc. Acknowledgements. This study was supported by the Fondecyt grant 1161818.</p>

Late Mesozoic and Cenozoic tectonic history of south central California

Tectonics ◽  
1984 ◽  
Vol 3 (6) ◽  
pp. 659-675 ◽  
Author(s):  
A. E. J. Engel ◽  
P. A. Schultejann
Keyword(s):  
Central California ◽  
Late Mesozoic ◽  
Tectonic History ◽  
South Central ◽  
History Of

Contribution a l'etude tectonique de la presqu'ile de Brogger (Spitsberg)

1966 ◽  
Vol S7-VIII (4) ◽  
pp. 560-566 ◽  
Author(s):  
Lucien Barbaroux
Keyword(s):  
Late Carboniferous ◽  
Late Paleozoic ◽  
Metamorphic Complex

Abstract New observations on the Brogger peninsula (Spitsbergen) show that the Hecla Hoek (Caledonide) geosynclinal metamorphic complex, reactivated by successive orogenies, overlaps Paleozoic and Cenozoic sedimentary formations in a northwest direction along a continuous front. The role of northwest-southeast-trending deformation in the Hercynian (late Paleozoic) and north-south deformation in the Tertiary assume greater importance than was heretofore accorded them. The existence of an Erzgebirgian (late Carboniferous) and a Saalian (mid-Permian) phase of Paleozoic orogeny can be shown.

Gneissic Alkalic Rocks and Carbonatites in the Frenchman's Cap Gneiss Dome, Shuswap Complex, British Columbia

1974 ◽  
Vol 11 (2) ◽  
pp. 304-318 ◽  
Author(s):  
W. J. McMillan ◽  
J. M. Moore Jr.
Keyword(s):  
Regional Metamorphism ◽  
Lava Flows ◽  
High Grade ◽  
Metamorphic Complex ◽  
Sedimentary Deposits ◽  
Gneiss Domes ◽  
The Core ◽  
Igneous Origin ◽  
Eastern Border ◽  
Shuswap Metamorphic Complex

Frenchman's Cap dome is one of a series of gneiss domes along the eastern border of the high-grade Shuswap metamorphic complex. The granitic gneisses which compose the core of the dome are enclosed in an envelope of metasedimentary rocks.Before Shuswap metamorphism and deformation, the rocks of the sedimentary envelope were intruded by concordant bodies of alkalic rocks and carbonatite. Other carbonatite bodies appear to have formed at or extruded onto the surface. It is not certain whether these are exhalative sedimentary deposits, lava flows, or pyroclastic deposits.Criteria which can be used to distinguish igneous alkalic rocks from those of metasomatic origin were almost entirely destroyed by regional metamorphism. A few relict igneous textures show that at least some of the alkalic gneisses are of igneous origin.

U–Pb constraints on the thermotectonic evolution of the Vernon antiform and the age of the Aberdeen gneiss complex, southeastern Canadian Cordillera

2006 ◽  
Vol 43 (2) ◽  
pp. 213-244 ◽  
Author(s):  
P Glombick ◽  
R I Thompson ◽  
P Erdmer ◽  
L Heaman ◽  
R M Friedman ◽  
...  
Keyword(s):  
Shear Zone ◽  
Hanging Wall ◽  
Ductile Deformation ◽  
Granitic Rocks ◽  
Tectonic Activity ◽  
Canadian Cordillera ◽  
Metamorphic Complex ◽  
Seismic Reflection Data ◽  
Gneiss Complex ◽  
Shuswap Metamorphic Complex

The Aberdeen gneiss complex is composed of complexly deformed migmatitic orthogneiss and paragneiss situated within the core of the Vernon antiform, a structure defined by a series of subparallel reflectors visible at upper to middle crustal depths (6–18 km) in seismic reflection data from the Vernon area of the Shuswap metamorphic complex. The Vernon antiform and the Aberdeen gneiss complex lie within the footwall of the gently west dipping (top to the west) Kalamalka Lake shear zone. Migmatitic gneiss exposed within the antiform records evidence (recorded as age domains in complexly zoned zircon grains) of three metamorphic events, occurring at 155–150, 90, and 66–51 Ma. The timing of magmatic events within the antiform includes emplacement of diorite at ~232 Ma, tonalite at ~151 Ma, granodiorite at 102 Ma, and monzonite at 52 Ma. Middle to Late Jurassic metamorphism resulted in widespread migmatization. Early Tertiary metamorphism (66–51 Ma) was coeval with the emplacement of granitic rocks and exhumation typical of other areas of the Shuswap metamorphic complex. Highly deformed orthogneiss situated within the hanging wall of the Kalamalka Lake shear zone, comprising the superstructure, was emplaced at ~171 Ma. Ductile deformation had ceased by 162 Ma. The complex metamorphic and magmatic evolution of the Vernon antiform, which is similar to other areas of the southern Canadian Cordillera including the Nicola horst, Mount Lytton – Eagle plutonic complex, Cariboo Mountains, and Mica Creek area, may reflect episodic tectonic activity at the plate margin.

Devonian Plutonism in South-Central British Columbia

1975 ◽  
Vol 12 (10) ◽  
pp. 1760-1769 ◽  
Author(s):  
Andrew V. Okulitch ◽  
R. K. Wanless ◽  
W. D. Loveridge
Keyword(s):  
British Columbia ◽  
Middle Devonian ◽  
Metamorphic Complex ◽  
Western Margin ◽  
South Central ◽  
Minimum Age ◽  
History Of ◽  
Shuswap Metamorphic Complex

An apparently tabular body of granitoid gneiss, 3 to 5 km wide and more than 70 km long, that lies along the western margin of the Shuswap Metamorphic Complex between Shuswap and Admas Lakes, shows intrusive relationships with Palaeozoic and older rocks and has yielded zircons whose minimum age is 372 Ma. This intrusion, together with other granitoid plutons in the area that appear to be related to it, provide evidence of widespread plutonism during Middle Devonian time near the western edge of the Paleozoic Cordillera geosyncline and necessitate significant revisions in the interpretation of the crustal history of this region.

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