Deformation of the western margin of the Omineca Belt near Crooked Lake, east-central British Columbia

1990 ◽  
Vol 27 (3) ◽  
pp. 414-425
Author(s):  
Jeffrey A. Fillipone ◽  
John V. Ross
Keyword(s):  
British Columbia ◽  
North America ◽  
Middle Jurassic ◽  
Phase 1 ◽  
Late Devonian ◽  
East Central ◽  
Western Margin ◽  
Metasedimentary Rocks ◽  
Narrow Zone ◽  
Minimum Age

The western margin of the Omineca Belt near Crooked Lake, British Columbia, consists of metasedimentary rocks (Snowshoe Group) and orthogneisses of the Barkerville terrane, structurally overlain by a mafic volcanic – sedimentary package of rocks belonging to the allochthonous Slide Mountain (Crooked Amphibolite) and Quesnel terranes (Triassic phyllite and Nicola Group). At least two episodes of regional deformational (phases 2 and 3) affected this composite package. Deformation and metamorphism (phase 1) in the Snowshow Group predate the formation of this package and are nowhere evident within the allochthonous terranes.Middle Jurassic metamorphism ranging from chlorite zone through sillimanite zone affected all units. Isograds are folded, together with the junction between the terranes, indicating that the metamorphic assemblages developed prior to folding of this boundary. Granitic orthogneiss (Boss Mountain, Quesnel Lake, and Perseus gneisses), having a minimum age of Late Devonian to Early Pennsylvanian, was intruded into and deformed with the Snowshoe Group during the earliest recognizable phase of deformation in the Barkerville terrane (phase 1). Slide Mountain terrane rocks occupy a narrow zone where large eastward displacement occurred during overthrusting of the Intermontane superterrane upon the western margin of North America in Middle Jurassic time.

Eocene age for Ag–Pb–Zn–Au vein and replacement deposits of the Kokanee Range, southeastern British Columbia

1992 ◽  
Vol 29 (1) ◽  
pp. 3-14 ◽  
Author(s):  
G. Beaudoin ◽  
J. C. Roddick ◽  
D. F. Sangster
Keyword(s):  
British Columbia ◽  
Middle Jurassic ◽  
Middle Eocene ◽  
Hanging Wall ◽  
Spatial Association ◽  
High Heat ◽  
Time Interval ◽  
Genetic Link ◽  
Metasedimentary Rocks ◽  
Magmatic Event

The Ag–Pb–Zn–Au vein and replacement deposits of the Kokanee Range, southeastern British Columbia, are hosted by the Middle Jurassic Nelson batholith and surrounding Cambrian to Triassic metasedimentary rocks in the hanging wall of the transcrustal Slocan Lake Fault, Field relations indicate that mineralization is younger than the Nelson batholith and a Middle Jurassic foliation in the Ainsworth area but coeval or older than Eocene unroofing of the Valhalla metamorphic core complex in the footwall of the Slocan Lake Fault. Lamprophyre and gabbro dykes are broadly coeval with mineralization and have biotite and hornblende K–Ar ages defining a short-lived Middle Eocene alkaline magmatic event between 52 and 40 Ma. An older, Early Cretaceous alkaline magmatic event (141 – 129 Ma) is possible but incompletely documented.K–Ar and step-heating 40Ar/39Ar analyses on hydrothermal vein and alteration muscovite indicate that hydrothermal fluids were precipitating vein and replacement deposits 58–59 Ma ago. Crosscutting relationships with lamprophyre dykes indicate the Kokanee Range hydrothermal system lasted for more than 15 Ma. Eocene crustal extension resulted in a high heat flow and structures which were probably responsible for hydrothermal fluid movement and flow paths.A 100 Ma time interval is documented between batholith emplacement and spatially associated mineralization, ruling out any genetic link between the two. Similar large age differences between granite intrusion and peripheral mineralization have recently been documented for two world-sea le Ag–Pb–Zn vein districts, which suggest that spatial association between granite and Ag–Pb–Zn mineralization is not sufficient to infer a genetic link.

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.

A new species of lobster (Astacidea, Erymidae) from the Smithers Formation (Middle Jurassic) of British Columbia, Canada

2007 ◽  
Vol 44 (12) ◽  
pp. 1791-1796 ◽  
Author(s):  
Rodney M Feldmann ◽  
James W Haggart
Keyword(s):  
British Columbia ◽  
New Species ◽  
North America ◽  
Middle Jurassic ◽  
Fourth Species ◽  
North Polar ◽  
A New Species

A single carapace and its counterpart of an erymoid lobster collected from the Middle Jurassic Smithers Formation in British Columbia, permits description of a new species, Eryma walkerae. The specimen represents only the fourth species of Eryma described from North America and documents a north polar route of dispersal for erymids into North America.

scholarly journals Detrital zircon geochronology of quartzose metasedimentary rocks from parautochthonous North America, east-central Alaska

Lithosphere ◽  
2017 ◽  
Vol 9 (6) ◽  
pp. 927-952 ◽  
Author(s):  
Cynthia Dusel-Bacon ◽  
Christopher S. Holm-Denoma ◽  
James V. Jones ◽  
John N. Aleinikoff ◽  
James K. Mortensen
Keyword(s):  
North America ◽  
Detrital Zircon ◽  
Zircon Geochronology ◽  
East Central ◽  
Detrital Zircon Geochronology ◽  
Metasedimentary Rocks

Late Paleozoic and Mesozoic terrane interactions in north-central British Columbia

1991 ◽  
Vol 28 (6) ◽  
pp. 947-957 ◽  
Author(s):  
Hubert Gabrielse
Keyword(s):  
British Columbia ◽  
North America ◽  
Middle Jurassic ◽  
Subsequent Development ◽  
Structural Data ◽  
Strike Slip ◽  
Granitic Rocks ◽  
Late Triassic ◽  
North Central ◽  
Dextral Strike Slip

Five clearly defined terranes, comprising from northeast to southwest, Ancestral North America, Slide Mountain, Quesnellia, Cache Creek, and Stikinia, are the dominant tectonic elements of north-central British Columbia. Stratigraphic, sedimentological, plutonic, metamorphic, and structural data show that the Slide Mountain Terrane evolved as a subduction, accretion, and island-arc complex during Permian time. Sedimentological data hint at the demise of the Slide Mountain and Cache Creek oceanic environments in the Permian or Early Triassic and Late Triassic, respectively. Subduction led to the development of volcanic–plutonic island arcs on Stikinia, Quesnellia, and locally on the Cache Creek Terrane in Late Triassic to Middle Jurassic time. Marked inter- and intra-terrane contraction in the Middle Jurassic resulted in the south westward thrusting of the Cache Creek Terrane onto Stikinia, the subsequent development of the Bowser Basin on Stikinia, and possible coeval culmination of the emplacement of Quesnellia and the Slide Mountain Terrane onto Ancestral North America. Deformation, metamorphism, and plutonism along the western margin of Ancestral North America closely followed these events. Contraction was succeeded by a dextral strike-slip regime during the mid-Cretaceous accompanied by the intrusion of voluminous potassic, silica-rich granitic rocks in Ancestral North America. The emplacement of Early to mid-Cretaceous plutons postdated the development of broad, open, regional anticlinoria and synclinoria, perhaps during Early Cretaceous time. The plutonic episode coincided approximately with initiation of the Sustut Basin. Dextral strike-slip faulting further disrupted Ancestral North America until post-Eocene time.

A note on the Quesnel Lake Gneiss, Caribou Mountains, British Columbia

1989 ◽  
Vol 26 (7) ◽  
pp. 1503-1508
Author(s):  
John R. Montgomery ◽  
John V. Ross
Keyword(s):  
British Columbia ◽  
Late Paleozoic ◽  
Structural Studies ◽  
Western Margin ◽  
Metasedimentary Rocks ◽  
The North ◽  
Deformational History ◽  
Isotope Studies ◽  
Caribou Mountains ◽  
North American Craton

The Quesnel Lake Gneiss is one of several large bodies of gneiss emplaced into the westernmost exposure of the Hadrynian to Paleozoic(?) metasedimentary rocks of the Snowshoe Group in the Omineca Belt, central British Columbia. The gneiss has a deformational history comparable to that of its enveloping rocks, and isotope studies indicate that its age of emplacement is Late Devonian to Early Mississippian and that its age of synkinematic metamorphism is mid-Jurassic. From petrochemical analyses and structural studies, we interpret the gneiss as being a late Paleozoic igneous intrusion into the probable western margin of the North American craton.

Geochronology and tectonic implications of magmatism and metamorphism, southern Kootenay Arc and neighbouring regions, southeastern British Columbia. Part I: Jurassic to mid-Cretaceous

1983 ◽  
Vol 20 (12) ◽  
pp. 1891-1913 ◽  
Author(s):  
D. A. Archibald ◽  
J. K. Glover ◽  
R. A. Price ◽  
E. Farrar ◽  
D. M. Carmichael
Keyword(s):  
British Columbia ◽  
North America ◽  
Regional Metamorphism ◽  
Granitic Rocks ◽  
Early Paleozoic ◽  
Small Bodies ◽  
Western Margin ◽  
The North ◽  
Windermere Supergroup ◽  
Igneous Activity

K–Ar dates and U–Pb zircon dates define three periods of igneous activity in the southern Kootenay Arc: (1) emplacement of late-synkinematic to post-kinematic granodioritic plutons in mid-Jurassic time (170–165 Ma) accompanying amphibolite-facies regional metamorphism; (2) emplacement of post-kinematic granitic plutons in mid-Cretaceous time (~100 Ma); and (3) emplacement of small bodies of syenite in Eocene time (~50 Ma) in the western part of the area. Micas from mid-Jurassic plutons that yield the oldest K–Ar dates (158–166 Ma) also yield plateau-shaped 40Ar/39Ar age spectra. Age spectra for biotites younger than these but older than 125 Ma reflect thermal overprinting.In southeastern British Columbia, the Kootenay Arc marks the transition from the North American rocks of the Cordilleran miogeocline to the tectonic collage of allochthonous terranes that have been accreted to it.Deformation, metamorphism, and plutonism recorded in rocks of the southern Kootenay Arc commenced in mid-Jurassic time as a composite allochthonous terrane was accreted to and overlapped the western margin of North America. The geochronology and metamorphic geothermobarometry show that in less than 10 Ma between 166 and 156 Ma: (1) rocks as young as the late Proterozoic Windermere Supergroup and the early Paleozoic Lardeau Group were carried rapidly to depths of 20–24 km while being deformed and intruded by granitic rocks of a hornblende–biotite suite that were also being emplaced at a much shallower level in the overriding allochthonous terrane; and (2) the miogeoclinal rocks of the Windermere Supergroup in the southern Kootenay Arc were then uplifted by more than 7 km at an estimated rate of 2 mm/year, and thrust over the allochthonous terrane prior to being intruded by post-kinematic granitic rocks, many of which belong to the two-mica suite of mid-Cretaceous age..

Geology of the Nemo Lakes belt, northern Valhalla Range, southeast British Columbia

1981 ◽  
Vol 18 (5) ◽  
pp. 944-958 ◽  
Author(s):  
Randall R. Parrish
Keyword(s):  
British Columbia ◽  
Large Scale ◽  
Phase 1 ◽  
Normal Fault ◽  
Columbia River ◽  
Ultramafic Rocks ◽  
Phase 2 ◽  
Metasedimentary Rocks ◽  
The North ◽  
Gneiss Complex

High-grade metasedimentary rocks, probably of both early Paleozoic and late Paleozoic – Triassic ages, underlie an area termed the Nemo Lakes belt between Slocan and Arrow Lakes in the northern Valhalla Range, southeastern British Columbia. The rocks have experienced two possibly related periods of major folding. Phase 1, accompanied and outlasted by metamorphism at P–T conditions of 5.0–6.8 kbar (500–680 MPa) and 630–680 °C, involved emplacement of ultramafic rocks, major faulting, and folding. Phase 2 involved large-scale inclined to upright folds which were dominantly south-verging, deforming the phase 1 fabric. Both phases probably occurred in the Middle to Late Jurassic, as part of the Columbian Orogeny.Rocks lithologically and structurally similar to those of the Nemo Lakes belt are found across the Rodd Creek fault near the Columbia River and extend the general continuity of the belt into the Shuswap metamorphic complex.Plutonic rocks, some of which bracket the movement on the Rodd Creek fault, the southern extension of the Columbia River fault zone, range in age from Middle Jurassic to EoceneIn the valley of Slocan Lake, a major normal fault is postulated on structural and metamorphic grounds and may be related to the north–south arching of the Valhalla gneiss complex. It is suggested that this arching and uplift, which followed phase 2 deformation, produced both the fault and a zone of cataclasis on the eastern side of the complex, and gave rise to its domal shape.

U–Pb zircon, monazite, and sphene ages for granitic orthogneiss of the Barkerville terrane, east-central British Columbia

1987 ◽  
Vol 24 (6) ◽  
pp. 1261-1266 ◽  
Author(s):  
J. K. Mortensen ◽  
J. R. Montgomery ◽  
J. Fillipone
Keyword(s):  
British Columbia ◽  
Metamorphic Event ◽  
Precise Estimate ◽  
Late Devonian ◽  
Second Phase ◽  
Combined Effects ◽  
East Central ◽  
Late Proterozoic

Granitic orthogneiss forms an important component of the Barkerville terrane of southeastern British Columbia. Rb–Sr whole-rock ages for the orthogneisses are ambiguous and range from Late Proterozoic to mid-Paleozoic, with large associated errors. U–Pb dating of zircon, monazite, and sphene has been employed in an attempt to establish precise crystallization ages for two of the orthogneiss bodies. U–Pb systematics for zircons from both bodies show the combined effects of inheritance of zircon cores and postcrystallization Pb loss. This complexity precludes a precise estimate of the age of emplacement of the granitic protoliths of the gneiss. The data do, however, constrain possible emplacement ages for the bodies to between 335 and 375 Ma (Late Devonian – mid-Mississippian).A U–Pb age of 174 ± 4 Ma for metamorphic sphene from one of the orthogneiss bodies is interpreted as dating the end of the second phase of deformation in the area. Two nearly concordant U–Pb ages of 114 and 117 Ma for monazite from the second body remain problematical. These data suggest either that the monazite grew during a relatively young shearing and (or) metamorphic event that locally affected the Barkerville terrane or that the closure temperatue for the U–Pb system in monazite is lower than had previously been inferred, or both.

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