Permian and older rocks of the southwestern Iskut River map area, northwestern British Columbia

McClelland, W.

doi:10.4095/132818

Cited by 11 publications

(14 citation statements)

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“…It corroborates the recent discovery of Precambrian xenocrystic zircon in the Late Triassic (211 +7/-5 Ma) Zippa Mountain syenite complex in western Stikinia (Bevier and Anderson, 1991;M. Furthermore, it lends support to the suggestions of Gehrels et al (1990), Samson et al (1991), Mortensen (1992), McClelland (1992, and Johnston (1993) that Stikinia may be partly equivalent to the Nisling Terrane (Fig. Furthermore, it lends support to the suggestions of Gehrels et al (1990), Samson et al (1991), Mortensen (1992), McClelland (1992, and Johnston (1993) that Stikinia may be partly equivalent to the Nisling Terrane (Fig.…”

Section: Summary Of U-pb Geochronologysupporting

confidence: 87%

Age and tectonic setting of Early Jurassic episodic volcanism along the northeastern margin of the Hazelton Trough, northern British Columbia

Thorkelson¹,

Mortensen²,

Marsden³

et al. 1995

Geological Society of America Special Papers

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Three temporally distinct Lower Jurassic volcanic successions are exposed in the Spatsizi River area of the Stikine Terrane (Stikinia), northern British Columbia. U-Pb zircon dating reveals that (1) the age of the oldest succession, the Griffith Creek volcanics, is ca. 206 Ma; and (2) the middle unit, the Cold Fish Volcanics, is ca. 194 Ma, consistent with its Early Pliensbachian biostratigraphic (ammonite) age. The age of the youngest unit, the Mount Brock volcanics, is Early to Middle Toarcian, also on the basis of ammonites. The Griffith Creek volcanics were folded along with older strata prior to deposition of the Cold Fish succession. An inherited component of zircon in some of the analyzed zircon fractions indicates that Precambrian basement or Lower Paleozoic strata of Precambrian provenance was present in the Stikinian subsurface. An evolved basement is also suggested by fluorine-rich compositions of high-silica Cold Fish rhyolites.The three volcanic successions were deposited in the Early Jurassic along the northeastern margin of the Hazelton Trough, a long-lived marine basin which lay between mainly subaerial volcanic arcs on the eastern and western sides of Stikinia. In Early Pliensbachian to Middle Toarcian time, strata in the Spatsizi River area recorded at least 2.6 km of subsidence, consistent with protracted regional subsidence in and around the trough. Extensional tectonism, and to a lesser degree thermal subsidence and local volcanic foundering, are considered the main causes of subsidence.

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Section: Summary Of U-pb Geochronologysupporting

confidence: 87%

Age and tectonic setting of Early Jurassic episodic volcanism along the northeastern margin of the Hazelton Trough, northern British Columbia

Thorkelson¹,

Mortensen²,

Marsden³

et al. 1995

Geological Society of America Special Papers

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“…Such connections would require significant lateral changes in stratigraphy, including an eastward increase in the abundance of quartzrich clastic strata and decrease in the proportion and extent of volcanic rocks. [35][36][37][38][39][40]. These rocks are overlain by Upper Jurassic through mid-Cretaceous marine strata of the Bowser Lake Group [41].…”

Section: Comparison Of Geologic Characteristics U-th-pb Ages and Lumentioning

confidence: 99%

“…Data from rocks of the Stikine terrane are relevant for comparison given that they occur along the eastern margin of the Coast Mountains batholith (Figure 1) and at least locally consist of upper Paleozoic-lower Mesozoic quartzrich metaclastic strata, marble, and metapelite [35][36][37][38][39][40]. In addition, Rusmore et al [9] report geochronologic and paleomagnetic data which they interpret as evidence that intrusive rocks in the study area were emplaced into these inboard assemblages.…”

Section: Comparison Of Geologic Characteristics U-th-pb Ages and Lumentioning

confidence: 99%

U-Th-Pb Geochronology and Lu-Hf Isotope Geochemistry of Detrital Zircons in Metasedimentary Rocks of the Southern Coast Mountains Batholith

et al. 2020

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Most metasedimentary rocks in the southern Coast Mountains batholith are of uncertain tectonic affinity because they occur in discontinuous pendants surrounded by large intrusive bodies, and many protolith features are obscured by regional deformation and metamorphism. This study uses U-Th-Pb ages and Lu-Hf isotope signatures of detrital zircons in metasedimentary rocks in Bute, Loughborough, and Knight Inlets in an effort to test possible correlations with the adjacent Wrangellia, Alexander, Taku, Yukon-Tanana, and Stikine terranes. Detrital zircons from metasedimentary samples yield ages that belong to age groups of 590-528 Ma (peak age of 560 Ma), 485-432 Ma (peak age of 452 Ma), 356-286 Ma (peak age of 307 Ma), and 228-185 Ma (peak ages of 215 and 198 Ma). A small number of ~1.1-1.9 Ga grains are also present. εHft values of the 590-185 Ma grains yield a progression from intermediate (0 to +5) values to more juvenile (mostly +4 to +15) values from Neoproterozoic through early Mesozoic time. The Comparison of these results with similar data sets from adjacent terranes demonstrates that primary connections with the Yukon-Tanana and Taku terranes are unlikely but are consistent with primary connections with the Wrangellia, Stikine, and/or Alexander terranes. Unfortunately, the available constraints are not sufficient to eliminate any of these options or the possibility that the pendants are a unique tectonic fragment. Zircons from the metasedimentary samples also yield U-Th-Pb ages of 165-128 Ma (peak age of 152 Ma) and 114-88 Ma (peak age of 102 Ma). εHft values of these zircon domains are mostly juvenile (+7 to +13). Comparison of U concentrations, U/Th values, and CL textures of zircons from the metasedimentary samples, leucocratic sills that intrude the pendants, and surrounding plutonic bodies suggests that most of the young grains, as well as widespread younger rims on older grains, grew during metamorphism associated with emplacement of the adjacent plutonic bodies. Some young grains were derived from thin felsic sills or veins that were unintentionally included in the sampled material.

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“…Paleozoic rocks of the Takhini and Boswell assemblages are inferred to be the depositional basement to Mesozoic arc rocks of Stikinia-Quesnellia beneath the northern Whitehorse trough. Elsewhere, these rocks are correlated with parts of the Yukon-Tanana terrane, which locally forms the basement to Stikinia (McClelland, 1992) and Quesnellia Nelson and Friedman, 2004;Roots et al, 2006). In southern Yukon, Mesozoic Stikinia is represented by volcanic and sedimentary strata of the Middle Triassic Joe Mountain Formation and the Upper Triassic Lewes River Group ( Fig.…”

Section: Intermontane Terranesmentioning

confidence: 99%

Birth of the northern Cordilleran orogen, as recorded by detrital zircons in Jurassic synorogenic strata and regional exhumation in Yukon

et al. 2015

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The Whitehorse trough is an Early to Middle Jurassic marine sedimentary basin that overlaps the Intermontane terranes in the northern Cordillera. Detrital zircon dates from eight Laberge Group sandstones from various parts of the trough all display a major Late Triassic-Early Jurassic peak (220-180 Ma) and a minor peak in the mid-Paleozoic (340-330 Ma), corresponding exactly with known igneous ages from areas surrounding the trough. Source regions generally have Early Jurassic (ca. 200-180 Ma) mica cooling dates, and the petrology of metamorphic rocks and Early Jurassic granitoid plutons flanking the trough suggests rapid exhumation during emplacement. These data suggest that subsidence and coarse clastic sedimentation in the trough occurred concurrently with rapid exhumation of the shoulders. Isolated occurrences of sandstone and conglomerate units with similar detrital zircon signatures occur west and east of the trough, as well as overlapping the Cache Creek terrane, indicating that either the trough was once more extensive, or isolated basins tapped similar sources. Development of these sedimentary basins and accompanying rapid exhumation in the northern Cordillera were coeval with the onset of orogenic activity in the hinterland of the southern Canadian Cordillera, and subsidence in the western Canada foreland sedimentary basin. The Whitehorse trough is interpreted as a forearc basin that progressively evolved into a collisional, synorogenic piggyback basin developed atop the nascent Cordilleran orogen. Upper Jurassic-Lower Cretaceous fluvial deposits overlapping the Whitehorse trough have detrital zircons that were mainly derived from recycling of the Laberge Group, but they also contain zircons exotic to the northern Intermontane terranes that are interpreted to reflect windblown detritus from the Late Jurassic-Early Cretaceous magmatic arc that developed either atop the approaching Insular terranes to the west or southern Stikinia.

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Permian and older rocks of the southwestern Iskut River map area, northwestern British Columbia

Cited by 11 publications

References 0 publications

Age and tectonic setting of Early Jurassic episodic volcanism along the northeastern margin of the Hazelton Trough, northern British Columbia

Age and tectonic setting of Early Jurassic episodic volcanism along the northeastern margin of the Hazelton Trough, northern British Columbia

U-Th-Pb Geochronology and Lu-Hf Isotope Geochemistry of Detrital Zircons in Metasedimentary Rocks of the Southern Coast Mountains Batholith

Birth of the northern Cordilleran orogen, as recorded by detrital zircons in Jurassic synorogenic strata and regional exhumation in Yukon

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