Detrital geochronology of pre-Mississippian strata in the northeastern Brooks Range, Alaska: Insights into the tectonic evolution of northern Laurentia

Johnson, Benjamin G.; Strauss, Justin V.; Toro, Jaime; Benowitz, Jeff; Ward, William P.; Hourigan, J. K.

doi:10.1130/l533.1

Cited by 20 publications

(9 citation statements)

References 115 publications

(192 reference statements)

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“…Oldow et al [34] discussed post-Jurassic translation along the PSZ, highlighting significant differences in the style of deformation and stratigraphic correlations between early Paleozoic strata north and south of this structure. These stratigraphic mismatches were documented further by Strauss et al [13] who proposed translation of the North Slope subterrane along the PSZ and related structures from a location adjacent to the Franklinian basin of the Canadian Arctic Islands (see also [19,20,23,35]). More recently, sinistral and dextral displacement along the PSZ was documented by von Gosen et al [15], with the majority of the sinistral translation inferred to occur in the middle Paleozoic.…”

Section: Introductionmentioning

confidence: 76%

“…These strata are disconformably overlain by texturally immature siliciclastic units of the Upper Ordovician-Lower Devonian(?) Clarence River Group [20,23]. The pre-Mississippian basinal succession is locally in tectonic contact with the Whale Mountain allochthon, an imbricated package of upper Cambrian mafic volcanic rocks, carbonate, and phyllite [22,23].…”

Section: Yukon Blockmentioning

confidence: 99%

“…Clarence River Group [20,23]. The pre-Mississippian basinal succession is locally in tectonic contact with the Whale Mountain allochthon, an imbricated package of upper Cambrian mafic volcanic rocks, carbonate, and phyllite [22,23]. The platformal succession is comprised of mixed siliciclastic and carbonate strata of the Tonian Mount Weller Group [19], which is overlain by the ca.…”

Section: Yukon Blockmentioning

confidence: 99%

“…Small populations of ca. 500-700 Ma zircon also occur in Ordovician-Devonian synorogenic strata of the Clarence River Group of the North Slope subterrane [20,23].…”

Section: Age and Provenance Of The Darcy Creek Formationmentioning

confidence: 99%

“…In contrast, other studies pointed out stratigraphic mismatches between these sedimentary successions [13,20], in addition to highlighting the allochthonous nature of oceanic rocks imbricated with these strata [22] and their association with an Ordovician-Silurian overlap assemblage potentially derived from the northern Caledonides [23]. These studies point to an origin of the North Slope subterrane adjacent to the Franklinian basin of the Canadian Arctic Islands (Figure 1) with subsequent translation through strike-slip displacement along the PSZ or associated fault zones along northern Laurentia (e.g., [15]).…”

Section: Introductionmentioning

confidence: 99%

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Pre-Mississippian Stratigraphic Architecture of the Porcupine Shear Zone, Yukon and Alaska, and Significance in the Evolution of Northern Laurentia

et al. 2021

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The origin and displacement history of terranes emplaced along the northern margin of North America remain contentious. One of these terranes is the North Slope subterrane of the Arctic Alaska-Chukotka microplate, which is separated from the northwestern margin of Laurentia (Yukon block) by the Porcupine Shear Zone of Alaska and Yukon. Here, we present new field observations, geological mapping, detrital zircon U-Pb geochronology, and sedimentary/igneous geochemistry to elucidate the stratigraphic architecture of deformed pre-Mississippian rocks exposed within the Porcupine Shear Zone, which we distinguish herein as the newly defined Ch’oodeenjìk succession. The oldest rocks in the Ch’oodeenjìk succession consist of siliciclastic strata of the Lahchah and Sunaghun formations (new names), which yield detrital zircon U-Pb age populations of ca. 1050-1250, 1350-1450, 1600-1650, and 2500-2800 Ma (n =800). This succession is overlain by chert-bearing dolostone and limestone of the Caribou Bar formation (new name) that contains vase-shaped microfossils and yields carbonate carbon (δ13Ccarb) and strontium (87Sr/86Sr) isotopic data that range from ca. -3‰ to +3‰ and 0.70636 to 0.70714, respectively. These data suggest that Lahchah, Sunaghun, and Caribou Bar formations are late Tonian in age. These Neoproterozoic rocks are intruded by Late Devonian (Frasnian-Famennian) felsic plutons and mafic dikes, one of which yielded a sensitive high-resolution ion microprobe-reverse geometry (SHRIMP-RG) U-Pb age of 380 ± 4 Ma. Neoproterozoic strata of the Ch’oodeenjìk succession are also unconformably overlain by Upper Devonian-Carboniferous (?) siliciclastic rocks of the Darcy Creek formation (new name), which yields detrital zircon populations of ca. 365–385, 420-470 and 625-835 Ma, in addition to Proterozoic age populations similar to the underlying Tonian strata. Together, these new stratigraphic, geochronological, geochemical, and micropaleontological data indicate that pre-Mississippian rocks exposed within the Porcupine Shear Zone most likely represent a peri-Laurentian crustal fragment that differs from the adjacent Yukon block and North Slope subterrane; thus, the Porcupine Shear Zone represents a fundamental tectonic boundary separating autochthonous Laurentia from various accreted peri-Laurentian crustal fragments.

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Section: Introductionmentioning

confidence: 76%

Section: Yukon Blockmentioning

confidence: 99%

Section: Yukon Blockmentioning

confidence: 99%

“…Small populations of ca. 500-700 Ma zircon also occur in Ordovician-Devonian synorogenic strata of the Clarence River Group of the North Slope subterrane [20,23].…”

Section: Age and Provenance Of The Darcy Creek Formationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pre-Mississippian Stratigraphic Architecture of the Porcupine Shear Zone, Yukon and Alaska, and Significance in the Evolution of Northern Laurentia

et al. 2021

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Detrital zircon U-Pb geochronological and Hf isotopic constraints on the geological evolution of North Yukon

Colpron¹,

McClelland²,

Strauss³

2019

Circum-Arctic Structural Events: Tectonic Evolution of the Arctic Margins and Trans-Arctic Links With Adjacent Orogens

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North Yukon lies at the intersection of two major tectonic domains that define the western and northern edges of the North American continent—the northern Cordilleran mountain belt and the Arctic Ocean. The pre-Carboniferous geology in North Yukon includes the Neoproterozoic−lower Paleozoic North Slope subterrane of the Arctic Alaska terrane and, south of the Porcupine shear zone, Mesoproterozoic−Paleozoic rocks of the Yukon stable block. The North Slope subterrane was deformed prior to deposition of Carboniferous and younger strata, and its paleogeographic origins are debated. North Yukon was deformed again during Cretaceous−Cenozoic development of the northern Cordilleran−Brookian orogen. To help refine understanding of the geological evolution of the region, we present detrital zircon U-Pb and Hf isotopic data for 21 sandstone and conglomerate samples from Neoproterozoic to Cenozoic strata collected across North Yukon, between ~69°15′N and 67°11′N. Neoproterozoic−Cambrian strata in the British Mountains are characterized by a dominance of Paleoproterozoic zircons (peak at 1.7–1.8 Ga), whereas samples from the Barn Mountains to the south have abundant Mesoproterozoic grains (1.0–1.5 Ga), suggesting these rocks may have been deposited along different segments of the northern Laurentian margin. Regional geophysics suggest these domains could be separated by a fault. Northeastern Laurentian origins are indicated by distinct early Neoproterozoic and Ordovician−Silurian zircons in Upper Silurian−Lower Devonian immature sandstone and conglomerate of the Clarence River Group and provide the most compelling evidence for large-scale translation along northern Laurentia. Precambrian detrital zircons in Carboniferous and younger strata reflect mostly recycling of local older strata. Carboniferous conglomerates all show Late Devonian peaks (365–378 Ma) consistent with erosion of nearby granitoid plutons. Triassic to Paleocene samples yielded a range of Neoproterozoic−Paleozoic zircons recycled from nearby Devonian flysch. Most significantly, these samples also yielded juvenile zircons that are close to depositional age, but for which arc sources are only known in southern Yukon and Alaska, more than 700 km away. These source regions are distinct from NE Russian sources inferred for early Brookian (Early Cretaceous) foreland deposits in Alaska.

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The Whale Mountain allochthon: A relic of the Iapetus Ocean preserved in the northeastern Brooks Range of Alaska and Yukon

Johnson

Strauss

Taylor

et al. 2019

Circum-Arctic Structural Events: Tectonic Evolution of the Arctic Margins and Trans-Arctic Links With Adjacent Orogens

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The Whale Mountain allochthon is a structural complex composed of lower Paleozoic mafic volcanic and marine sedimentary rocks that are exposed within three fault-bounded, east–west-trending belts in the northeastern Brooks Range of Alaska and Yukon. Each belt is characterized by a unique structural and stratigraphic architecture. Trace-element systematics from the volcanic rocks define distinctive suites that are geographically restricted to each belt. The volcanic rocks of the southern belt (the Marsh Fork volcanic rocks) have a tholeiitic character and rare earth element trends that resemble modern mid-ocean-ridge basalt. The volcanic rocks of the central belt (the Whale Mountain volcanic rocks) and northern belt (Ekaluakat formation; new name) both have an alkaline character, but the northern belt rocks are significantly more enriched in the incompatible trace elements. New zircon U-Pb data from two volcaniclastic rock units, one from the southern belt and another from central belt, yield unimodal age populations that range from ca. 567 to 474 Ma, with weighted averages of 504 ± 11 and 512 ± 1.4 Ma for each sample. In the central and southern belts of the allochthon, basalt flows are interbedded with discontinuous limestone and dolostone units that contain trilobites and agnostoid arthropods. Three distinct trilobite faunas of late Cambrian (Furongian) age were recovered from widely separated localities. The scarcity of uniquely Laurentian genera, coupled with an abundance of distinctive species that could not be assigned to any established Furongian genus, argues against models that invoke extrusion of these volcanic rocks onto the autochthonous Laurentian shelf or slope. It is thus proposed that the Whale Mountain allochthon formed in a peri-Laurentian setting, possibly as disparate fragments of the northern Iapetus Ocean that were assembled in an ancient accretionary wedge and subsequently accreted to the northern margin of Laurentia during the early Paleozoic.

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Detrital geochronology of pre-Mississippian strata in the northeastern Brooks Range, Alaska: Insights into the tectonic evolution of northern Laurentia

Cited by 20 publications

References 115 publications

Pre-Mississippian Stratigraphic Architecture of the Porcupine Shear Zone, Yukon and Alaska, and Significance in the Evolution of Northern Laurentia

Pre-Mississippian Stratigraphic Architecture of the Porcupine Shear Zone, Yukon and Alaska, and Significance in the Evolution of Northern Laurentia

Detrital zircon U-Pb geochronological and Hf isotopic constraints on the geological evolution of North Yukon

The Whale Mountain allochthon: A relic of the Iapetus Ocean preserved in the northeastern Brooks Range of Alaska and Yukon

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