The Selkirk fan structure of the southeastern Canadian Cordillera

Brown, Richard L.; Tippett, C R

doi:10.1130/0016-7606(1978)89<548:tsfsot>2.0.co;2

Cited by 33 publications

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“…Work in the fold and thrust belt has revealed the well known pattern and timing of imbricate thrusting and "thin-skin" tectonics (Bally et al 1966;Price and Mountjoy 1970). Work in the transitional area between the thrust belt and the metamorphic core has documented a complex three-stage deformational history (Ross 1970;Brown and Tippett 1978;Simony et al 1980). Brown (1978) further outlined a tectonic model suggesting that the metamorphic core experienced polyphase deformation and was "consolidated" before the development of the fold and thrust belt.…”

Section: Introductionmentioning

confidence: 98%

Structural and metamorphic relationships between the Mount Ida and Monashee Groups at Mara Lake, British Columbia

Nielsen¹

1982

Can. J. Earth Sci.

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Mara Lake, British Columbia straddles the boundary between the Monashee Group on the east and the Mount Ida Group on the west. Correlation of units across the southern end of Mara Lake indicates lithologic continuity between parts of the groups. Both groups have experienced four phases of deformation. Phases one and two are tight and recumbent, trending to the north and to the west, respectively. Phases three and four are open to closed and upright, trending northwest and northeast, respectively. Second-phase deformation includes large-scale tectonic slides that separate areas of consistent vergence. Slide surfaces are folded by thud-and fourth-phase structures and outline domal outcrop patterns. Metamorphic grade increases from north to south along the west side of Mara Lake. Calc-silicate reactions involving the formation of diopside are characteristic. From west to east increasing grade is evident in the reaction of muscovite + quartz producing sillimanite + K-feldspar + water. These prograde reactions are related to relative position in the second-phase structure. The highest grade is located near the lowest slide surface. Greenschist conditions accompanied phase-three deformation. Fourth phase is characterized by hydrothermal alteration, brittle fracturing, and local faulting. First-phase deformation appears to be pre-Late Triassic whereas second and third phases are post-Late Triassic and pre-Cretaceous. The fourth phase is part of a regional Tertiary event. The thud folding event is correlated with the development of the Chase antiform and the second-phase folding is related to the pervasive east-west fabric of the Shuswap Complex. The timing of these events indicates that the metamorphic core zone of the eastern Cordillera was relatively rigid during the late Mesozoic foreland thrust development. Ductile deformation significantly preceded thrusting and developed a fabric almost at right angles to the trend of the thrust belt. Le lac Mara en Colombie Britannique recouvre la limite entre le groupe Monashee ti l'est et le groupe Mont Ida a l'ouest. La comklation des unitks lithologiques au travers l'extrkmitk sud du lac Mara indique une continuitk lithologique entre les segments des deux groupes. Les deux groupes ont subi quatre phases de dkformation. La premikre et la deuxikme phases foment des plis s e d s et couchks, respectivement en direction nord et ouest. Les troisikme et quatritme phases foment des plis ouverts B fermks et droits, respectivement en direction nord-ouest et nord-est. La deuxikme phase de dkformation inclut des glissements tectoniques de grandes dimensions qui dparent des rkgions h dkversement constant. Les surfaces de glissement sont plisskes par des structures causkes par les troisikme et quatrikme phases de dkformation et dklimitent les rkpartitions d'affleurements en forme de dame. Le degt-6 d'intensitk du mktamorphisme s'accroit du nord vers le sud le long de la rive ouest du lac Mara. Desr6actions calco-silicatkes menant h la formation de diopside sont caractkristiques. La rkactio...

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Section: Introductionmentioning

confidence: 98%

Structural and metamorphic relationships between the Mount Ida and Monashee Groups at Mara Lake, British Columbia

Nielsen¹

1982

Can. J. Earth Sci.

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“…Folds of this generation are strongly overturned toward the northeast adjacent to the Rocky Mountain Trench and become upright to overturned to the southwest as they diminish in intensity in the central part of the Selkirk Mountains. The superposition of these two phases of deformation with opposed sense of overturning has given rise to the Selkirk Fan structure that dominates the geometry of the northern Selkirks (Tippett 1976;Brown et al 1977b;Brown and Tippett 1978).…”

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confidence: 98%

Stratigraphy, facies changes, and correlations in the northern Selkirk Mountains, southern Canadian Cordillera

Brown¹,

Tippett²,

Lane³

1978

Can. J. Earth Sci.

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The Hadrynian Horsethief Creek Group that underlies much of the northern Selkirk Mountains is divided into three members. The upperpelitic member is overlain by latest Hadrynian to Lower Cambrian rocks of the Hamill Group and is correlated with the Yankee Belle Formation of the Cariboo Group in the Cariboo Mountains to the northwest. The underlying middle marble member is correlated with the Cunningham Formation, and the lowest exposed lower pelitic member with the Isaac Formation.Westward thickening of the Horsethief Creek Group is paralleled by agradational change in the upper pelitic member from a predominantly clastic sequence to the east to a predominantly calcareous sequence to the west. The overlying Hamill Group also changes in character, becoming more pelitic and interdigitating with basaltic metavolcanics toward the west. These facies changes are compatible with results from adjacent areas that point to deposition on a continental shelf in late Proterozoic to early Paleozoic time.Le gt-oupe de Horsethief Creek de 1'Hadrynien qu'on rencontre sous presque toute la partie nord des monts Selkirk se divise en trois membres. Le membre pelitique superieur est recouvert par les roches du groupe de Hamill, fin de 1'Hadrynien jusqu'au Cambrien inferieur, et est correlatif avec la formation de Yankee Belle du groupe de Cariboo dans les monts Cariboo au nord-ouest. Le membre intermediaire compose de marbre est correlatif avec la formation de Cunningham et le mernbre p6litique infkrieur avec la formation d'lsaac.L'Epaississernent i I'ouest du groupe de Horsethief Creek s'xcompagne d'un chanpernent padationnel dans te memhre pelitique supirieur d'une skquence surtout clastique B I'estjusqu'h une sCquence calcareuse B I'ouest. L e s caract6ristiques du groltpe de Hamill susjacent changent aussi pour devenir plus p6litiques et avec interstratification dans les roches basaltiques mCtavolcaniques a I'ouest. Ces changements de facies sont compatibles avec les observations dans fes rkgions adjacentes qui indiquent le dep6t sur une plate-forme continentale I la fin du RotCrozoique ou au debut du Paleozoique.

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“…It is the largest of all the Cordilleran metamorphic core complexes, and in the original conception of the problem, it was the type example and the source of the name (see my "Introduction" to this volume). As outlined earlier, studies indicate that some of the metamorphism is as old as Paleozoic and much of it is at least as old as Jurassic (Okulitch and others, 1975;Read and Okulitch, 1977;Brown and Tippett, 1978;Wheeler and Gabrielse, 1972;Hyndman, 1968). There are dated Upper Jurassic to middle Cretaceous plutons that crosscut metamorphic rocks (Gabrielse and Reesor, 1974).…”

Section: Tectonic Significancementioning

confidence: 91%

“…The northern complexes are found in a region that was probably affected by middle and late Paleozoic Antler-Sonoma deformation and, in the case of the Shuswap complex, some Paleozoic metamorphism (Okulitch and others, 1975;Read and Okulitch, 1977;Brown and Tippett, 1978). Southward in Nevada and Arizona, the complexes lie well east or south of any profound Paleozoic thermal or tectonic events.…”

Section: Pre-mesozoic Tectonic Trendsmentioning

confidence: 97%

“…From regional relationships in Canada, some of the metamorphism is Paleozoic, and most of it is at least as old as Middle Jurassic (Wheeler and Gabrielse, 1972;Brown and Tippett, 1978). Ironically, recent work in the southern Rocky Mountains of Canada suggests that much of the polyphase deformation and metamorphism so characteristic of on June 29, 2015 memoirs.gsapubs.org Downloaded from the Shuswap terrane is pre-Late Jurassic (Brown, 1978;Wheeler and Gabrielse, 1972) and thus earlier than the well-documented Late Jurassic to early Tertiary folding and thrusting to the east.…”

Section: Relationship To Mesozoic-early Cenozoic Trendsmentioning

confidence: 98%

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Cordilleran metamorphic core complexes: An overview

Coney¹

1980

Geological Society of America Memoirs

383

237

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More than 25 distinctive, isolated metamorphic terranes extend in a narrow, sinuous belt from southern Canada into northwestern Mexico along the axis of the North American Cordillera. Appreciation of these terranes has evolved slowly, and more than half of them have been recognized only since 1970. Growing evidence shows that these metamorphic terranes and related features evolved in part during early to middle Tertiary time (55 to 15 m.y. B.P.), that is, after the Laramide orogeny but before basin-range faulting. These terranes have been termed "metamorphic core complexes."The complexes are characterized by a generally heterogeneous, older metamorphic-plutonic basement terrane overprinted by low-dipping lineated and foliated mylonitic and gneissic fabrics. An unmetamorphosed cover terrane is typically attenuated and sliced by numerous subhorizontal younger-on-older faults. Between the basement and the cover terranes is a zone of "decollement" and/or steep metamorphic gradient with much brecciation and kinematic structural relationships indicative of sliding and detachment. Plutonic rocks as young as early to middle Tertiary age are deformed in the basement terranes of many of the complexes, and some of the deformed cover includes continental sedimentary and volcanic rocks of early to middle Tertiary age.Some complexes exhibit evidence of prolonged deformation and metamorphism extending back into Mesozoic and even Paleozoic time. All the complexes, however, reveal an early to middle Tertiary deformational and metamorphic overprint that is interpreted to be mainly of extensional origin. The extension coincided with a vast plutonic-volcanic flare-up of magmatic arc affinity mainly during Eocene time in the Pacific Northwest and mainly during late Eocene-Oligocene to middle Miocene time south of the Snake River Plain. The exact tectonic significance of the complexes remains obscure. Their extensional aspect clearly postdates, and seems unrelated to, Cretaceous and early Tertiary Sevier and Laramide compressional tectonics, but predates the more obvious late Tertiary basin-range extension and rifting. 7

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The Selkirk fan structure of the southeastern Canadian Cordillera

Cited by 33 publications

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Structural and metamorphic relationships between the Mount Ida and Monashee Groups at Mara Lake, British Columbia

Structural and metamorphic relationships between the Mount Ida and Monashee Groups at Mara Lake, British Columbia

Stratigraphy, facies changes, and correlations in the northern Selkirk Mountains, southern Canadian Cordillera

Cordilleran metamorphic core complexes: An overview

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