U–Pb geochronometry in the Horseranch Range, northern Omineca Belt, British Columbia, Canada

1994 ◽  
Vol 31 (2) ◽  
pp. 341-350
Author(s):  
Heather E. Plint ◽  
Randall R. Parrish
Keyword(s):  
British Columbia ◽  
Regional Metamorphism ◽  
Granitic Rocks ◽  
Precambrian Basement ◽  
North Central ◽  
Magmatic Rocks ◽  
Granitic Magmatism ◽  
Common Observation ◽  
Western Side ◽  
Dextral Strike Slip

A U–Pb geochronometric study of granitic rocks in the Horseranch Range in the northern Omineca Belt, north-central British Columbia, was carried out to determine the age of deformation, metamorphism, and magmatism and to determine if Precambrian basement is exposed in the range.Our results document Eocene (48–54 Ma) and late Early Cretaceous (113 Ma) granitic magmatism, limit the regional schistosity development to 113 Ma and older, and constrain the peak of syn- to posttectonic regional metamorphism to about 113 Ma. There is no direct evidence for Jurassic metamorphism, although our data do not preclude it. Dextral, oblique-slip mylonitization along the western side of the range is, in part, of Eocene age and related to transtensional tectonics synchronous with movement along regional, dextral strike-slip faults. No Precambrian basement was identified. However, U–Pb data indicate Early Proterozoic inheritance in some of the granitic rocks, a common observation in magmatic rocks of the Omineca Belt.

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.

scholarly journals Cretaceous Granitic Magmatism in South-Central Vietnam: Constraints from Zircon U–Pb Geochronology

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Huu Hiep NGUYEN ◽  
Nhu Sang PHAM ◽  
Van Long HOANG ◽  
Carter ANDREW ◽  
Vinh Hau BUI ◽  
...  
Keyword(s):  
Granitic Rocks ◽  
Published Data ◽  
Magmatic Rocks ◽  
South Central ◽  
Basement Rocks ◽  
Central Vietnam ◽  
Granitic Magmatism ◽  
Granite Samples

South-central Vietnam abundantly presents magmatic rocks with larger volumes ofCretaceous granitic rocks. In this study, zircon U–Pb geochronology of granite samples from the Deoca,Ankroet, and Dinhquan complexes in south-central Vietnam are utilized to investigate Cretaceousgranitic magmatism. According to U–Pb analysis results, zircon ages of granitic rocks display the Deocaat ~113–92 Ma, the Ankroet at ~103–98 Ma, and the Dinhquan at ~97–113 Ma. The range of ages isnarrow from 113 to 92 Ma, with most common ages date at ~100 Ma. Published data and our resultsdisplay that Cretaceous granitic magmatism was active between ~87–118 Ma and most active at ~100Ma in south-central Vietnam. Additionally, the Deoca and Dinhquan complexes show inherited ages inTriassic followed by Proterozoic and Carboniferous to Ordovician. The obtained ages indicate that Itypegranitic rocks could be derived from melting of basement rocks. Our study suggests that I-typegranitic rocks in south-central Vietnam were significantly intruded around 100 Ma.

Geochemical characterization of mid-Cretaceous granitoids of the Kootenay Arc in the southern Canadian Cordillera

1993 ◽  
Vol 30 (5) ◽  
pp. 1076-1090 ◽  
Author(s):  
Alan D. Brandon ◽  
Richard StJ. Lambert
Keyword(s):  
British Columbia ◽  
Regional Metamorphism ◽  
Crustal Thickening ◽  
Precambrian Basement ◽  
Crustal Anatexis ◽  
Volcanic Arcs ◽  
North American Continent ◽  
Isotopic Compositions ◽  
The North ◽  
Host Rocks

Within southeast British Columbia, mid-Cretaceous granitoid batholiths are exposed in the Omineca Belt, a north–south-trending metamorphic and plutonic orogenic belt. The Bugaboo, Horsethief Creek, and Fry Creek batholiths are post-kinematic with respect to regional metamorphism that affected their host rocks, and are composed of hornblende and biotite granodiorites and granites in all three batholiths, and two-mica granites in Fry Creek. The biotite granites are weakly peraluminous, have initial εSr ranging from + 36 to + 56 and initial εNd ranging from −4.8 to −7.5, and overlap the range of Nd–Sr isotopic compositions for Precambrian basement gneisses and Proterozoic metasediments found in southeast British Columbia. The initial 206Pb/204Pb versus 208Pb/204Pb and 207Pb/204Pb for these granitoids lie in bands between model lower and upper crustal Pb isotopic compositions above the Northern Hemisphere Reference Line for oceanic basalts. These granitoids have high Nb and Rb and low Ba abundances relative to granites found in volcanic arcs. The two-mica granites are strongly peraluminous and have εSr ranging from + 170 to + 470, εNd ranging from −10 to−21, and more radiogenic initial Pb-isotope ratios than the biotite granites. The two-mica granites have trace element compositions similar to those of granites found in within-plate and collisional tectonic settings.We favor a model for crustal anatexis of Precambrian basement gneisses and Proterozoic metapelites to produce the mid-Cretaceous biotite granites and two-mica granites, respectively. Crustal anatexis was likely in response to crustal thickening that occurred during the Mesozoic in southeast British Columbia as exotic terranes collided with and were accreted to the western edge of the North American continent.

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..

scholarly journals Provenance of the Permian Malužiná Formation sandstones (Malé Karpaty Mountains, Western Carpathians): evidence of garnet and tourmaline mineral chemistry

2015 ◽  
Vol 66 (2) ◽  
pp. 83-97 ◽  
Author(s):  
Marek Vďačný ◽  
Peter Bačík
Keyword(s):  
Regional Metamorphism ◽  
Mineral Chemistry ◽  
Source Rocks ◽  
Granitic Rocks ◽  
Western Carpathians ◽  
Low Grade ◽  
Magmatic Rocks ◽  
Potential Source ◽  
Ophiolitic Rocks ◽  
Central Western Carpathians

Abstract The chemistry of detrital garnets (almandine; spessartine-, grossular-, and pyrope-rich almandine; andradite) and mostly dravitic tourmalines from three sandstone samples of the Permian Malužiná Formation in the northern part of the Malé Karpaty Mts (Western Carpathians, SW Slovakia) reveals a great variability of potential source rocks. They comprise (1) low-grade regionally metamorphosed rocks (metacherts, blue schists, metapelites and metapsammites), (2) contact-thermal metamorphic calcareous rocks (skarns or rodingites), (3) garnet-bearing mica schists and gneisses resulting from the regional metamorphism of argillaceous sediments, (4) amphibolites and metabasic sub-ophiolitic rocks, (5) granulites, (6) Li-poor granites and their associated pegmatites and aplites as well as (7) rhyolites. Consequently, the post-Variscan, rift-related sedimentary basin of the Malužiná Formation originated in the vicinity of a low- to high-grade crystalline basement with granitic rocks. Such lithological types of metamorphic and magmatic rocks are characteristic for the Variscan terranes of the Central Western Carpathians (Tatricum and Veporicum Superunits).

Using perceptual maps to communicate concepts of Sustainable Forest Management – Collaborative research with the Office of the Wet'suwet'en Nation in British Columbia

2005 ◽  
Vol 81 (3) ◽  
pp. 381-386
Author(s):  
S. Denise Allen
Keyword(s):  
British Columbia ◽  
Forest Management ◽  
Collaborative Research ◽  
Sustainable Forest Management ◽  
Software Tool ◽  
Decision Makers ◽  
North Central ◽  
Criteria And Indicators ◽  
Perceptual Maps ◽  
Forest Resources Management

This article discusses collaborative research with the Office of the Wet'suwet'en Nation on their traditional territories in north-central British Columbia, Canada, a forest-dependent region where contemporary and traditional forest resources management regimes overlap. In-depth personal interviews with the hereditary chiefs and concept mapping were used to identify social-ecological linkages in Wet'suwet'en culture to inform the development of culturally sensitive social criteria and indicators of sustainable forest management (SFM) in this region. The preliminary results demonstrate how the CatPac II software tool can be applied to identify key component concepts and linkages in local definitions of SFM, and translate large volumes of (oral) qualitative data into manageable information resources for forest managers and decision-makers. Key words: social criteria and indicators, sustainable forest management, qualitative research, Wet'suwet'en

Stages of Late Palaeozoic deformation and intrusive activity in the western part of the North Patagonian Massif (southern Argentina) and their geotectonic implications

2008 ◽  
Vol 146 (1) ◽  
pp. 48-71 ◽  
Author(s):  
W. VON GOSEN
Keyword(s):  
Regional Metamorphism ◽  
The North ◽  
Magmatic Rocks ◽  
Late Palaeozoic ◽  
Intrusive Rocks ◽  
Gondwana Margin ◽  
Intrusive Activity ◽  
Magmatic History ◽  
Crust Deformation ◽  
Deformational Event

AbstractAnalyses of structures in the western part of the North Patagonian Massif (southern Argentina) suggest a polyphase evolution, accompanied by continuous intrusive activity. The first two deformations (D1, D2) and metamorphism affected the upper Palaeozoic, partly possibly older Cushamen Formation clastic succession and different intrusive rocks. A second group of intrusions, emplaced after the second deformational episode (D2), in many places contain angular xenoliths of the foliated country rocks, indicating high intrusive levels with brittle fracturing of the crust. Deformation of these magmatic rocks presumably began during (the final stage of) cooling and continued under solid-state conditions. It probably coincided with the third deformational event (D3) in the country rocks. Based on published U–Pb zircon ages of deformed granitoids, the D2-deformation and younger event along with the regional metamorphism are likely to be Permian in age. An onset of the deformational and magmatic history during Carboniferous times, however, cannot be excluded. The estimated ~W–E to NE–SW compression during the D2-deformation, also affecting the first group of intrusive rocks, can be related to subduction beneath the western Patagonia margin or an advanced stage of collisional tectonics within extra-Andean Patagonia. The younger ~N–S to NE–SW compression might have been an effect of oblique subduction in the west and/or continuing collision-related deformation. As a cause for its deviating orientation, younger block rotations during strike-slip faulting cannot be excluded. The previous D2-event presumably also had an effect on compression at the northern Patagonia margin that was interpreted as result of Patagonia's late Palaeozoic collision with the southwestern Gondwana margin. With the recently proposed Carboniferous subduction and collision south of the North Patagonian Massif, the entire scenario might suggest that Patagonia consists of two different pieces that were amalgamated with southwestern Gondwana during Late Palaeozoic times.

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