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

Johnson, Benjamin G.; Strauss, Justin V.; Taylor, John F.; Ward, William P.; Colpron, Maurice; McClelland, William C.; Toro, Jaime

doi:10.1130/2018.2541(20)

Cited by 5 publications

(1 citation statement)

References 47 publications

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“…This structurally complex unit is part of the "Romanzof Mountains southern belt of pre-Mississippian rocks" described by Moore et al (1992). The Romanzof formation is included in the Whale Mountain allochthon of Johnson et al (2019) and Strauss et al (2019), who interpret it to have been deposited in a deep ocean basin prior to being deformed during the Romanzof orogeny.…”

Section: Romanzof Formationmentioning

confidence: 99%

Ulungarat Basin: Record of a major Middle Devonian to Mississippian syn-rift to post-rift tectonic transition, eastern Brooks Range, Arctic Alaska

Anderson

Meisling²

2021

Geosphere

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The Ulungarat Basin of Arctic Alaska is a unique exposed stratigraphic record of the mid-Paleozoic transition from the Romanzof orogeny to post-orogenic rifting and Ellesmerian passive margin subsidence. The Ulungarat Basin succession is composed of both syn-rift and post-rift deposits recording this mid-Paleozoic transition. The syn-rift deposits unconformably overlie highly deformed Romanzof orogenic basement on the mid-Paleozoic regional angular unconformity and are unconformably overlain by post-rift Endicott Group deposits of the Ellesmerian passive margin. Shallow marine strata of Eifelian age at the base of the Ulungarat Formation record onset of rifting and limit age of the Romanzof orogeny to late Early Devonian. Abrupt thickness and facies changes within the Ulungarat Formation and disconformably overlying syn-rift Mangaqtaaq Formation suggest active normal faulting during deposition. The Mangaqtaaq Formation records lacustrine deposition in a restricted down-faulted structural low. The unconformity between syn-rift deposits and overlying post-rift Endicott Group is interpreted to be the result of sediment bypass during deposition of the outboard allochthonous Endicott Group. Within Ulungarat Basin, transgressive post-rift Lower Mississippian Kekiktuk Conglomerate and Kayak Shale (Endicott Group) are older and thicker than equivalents to the north. North of Ulungarat Basin, deformed pre-Middle Devonian rocks were exposed to erosion at the mid-Paleozoic regional unconformity for ~50 m.y., supplying sediments to the rift basin and broader Arctic Alaska rifted margin beyond. Although Middle Devonian to Lower Mississippian chert- and quartz-pebble conglomerates and sandstones across Arctic Alaska share a common provenance from the eroding ancestral Romanzof highlands, they were deposited in different tectonic settings.

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Section: Romanzof Formationmentioning

confidence: 99%

Ulungarat Basin: Record of a major Middle Devonian to Mississippian syn-rift to post-rift tectonic transition, eastern Brooks Range, Arctic Alaska

Anderson

Meisling²

2021

Geosphere

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Paleozoic evolution of the northern Laurentian margin: Evaluating links between the Caledonian, Ellesmerian, and Cordilleran orogens

McClelland

Strauss

Gilotti

et al. 2023

Laurentia: Turning Points in the Evolution of a Continent

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The passive margins of Laurentia that formed during Neoproterozoic–Cambrian breakup of the supercontinent Rodinia record subsequent histories of contraction and translation. This contribution focuses on the northern margin of Laurentia, where recent geologic and geochronologic data have provided new insight into the evolution of northern North America. The Laurentian margin in East and North-East Greenland records synorogenic sedimentation and deformation associated with the Caledonian orogeny—the Silurian to Devonian continent-continent collision between Baltica and Laurentia that followed closure of the northern tract of the Iapetus Ocean. The timing of ultrahigh-pressure metamorphism and simultaneous sinistral and dextral strike-slip faulting in North-East Greenland indicates that the Himalayan-style orogen persisted through the Devonian. In contrast, the Franklinian margin further west records sinistral strike-slip translation of allochthonous crustal blocks and arc fragments starting in the Ordovician–Silurian and culminating with the Devonian– Carboniferous Ellesmerian orogeny, the origin of which remains enigmatic. We suggest that Ellesmerian deformation was related to widespread transpression associated with northward motion of Laurentia during Acadian and Neo-Acadian deformation along the Appalachian margin rather than orthogonal ocean basin closure and microcontinent-continent collision. The Pearya terrane and North Slope subterrane of the Arctic Alaska terrane, separated from the Franklinian passive margin by the Petersen Bay fault and Porcupine shear zone, respectively, best preserve the Paleozoic translational and transpressional history of the northern Laurentian margin. These two major structures record a complex history of terrane accretion and translation that defines the Canadian Arctic transform system, which truncated the Caledonian suture to the east and ultimately propagated early Paleozoic subduction to the Cordilleran margin of western Laurentia.

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Late Ediacaran–early Cambrian rifting along the northern margin of Laurentia: constraints from the Yelverton Formation of Ellesmere Island, Canada

Faehnrich,

McClelland,

Webb

et al. 2023

Can. J. Earth Sci.

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Neoproterozoic to early Paleozoic strata exposed along the northeastern margin of North America (Franklinian Basin) record a prolonged history of rifting and passive margin development. An episode of Ediacaran–Cambrian extension is potentially recorded in volcanic and sedimentary rocks of the Yelverton Formation, exposed on northern Ellesmere Island, Nunavut, Canada. Here, we present new whole-rock trace element and isotope geochemistry and hornblende 40Ar/39Ar geochronology from intrusive and extrusive rocks of the Yelverton Formation, along with isotope geochemistry from carbonate rocks underlying the volcanics and detrital zircon U–Pb and Lu–Hf isotopic data from the Yelverton Formation and overlying Grant Land Formation. The carbonate strata yielded an average 87Sr/86Sr value of 0.7076 ( n = 6), constraining the overlying volcanics to the late Ediacaran–early Cambrian (ca. 570–530 Ma). Flows and dikes/sills show three distinct compositions: (1) a depleted, low La/YbPM and Th/Nb group, (2) an enriched, higher La/YbPM and low Th/Nb group, and (3) a low to moderate La/YbPM and high Th/Nb group. One of the high Th/Nb intrusions produced saddle-shaped 40Ar/39Ar hornblende spectra with ca. 482 ± 7 Ma age minima and Silurian–Devonian inverse isochron ages, highlighting a hitherto unknown suite of younger intrusions and volcanic rocks. The trace element geochemistry and 143Nd/144Nd(t) ratios of enriched and depleted volcanic rocks of the indisputable Yelverton Formation are consistent with decompression melting during rifting along a continental margin. We suggest that late Ediacaran–early Cambrian rifting recorded in the Yelverton Formation resulted in the separation of peri-Laurentian terranes, such as the North Slope subterrane and eventual development of the passive margin of northern Laurentia.

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

Cited by 5 publications

References 47 publications

Ulungarat Basin: Record of a major Middle Devonian to Mississippian syn-rift to post-rift tectonic transition, eastern Brooks Range, Arctic Alaska

Ulungarat Basin: Record of a major Middle Devonian to Mississippian syn-rift to post-rift tectonic transition, eastern Brooks Range, Arctic Alaska

Paleozoic evolution of the northern Laurentian margin: Evaluating links between the Caledonian, Ellesmerian, and Cordilleran orogens

Late Ediacaran–early Cambrian rifting along the northern margin of Laurentia: constraints from the Yelverton Formation of Ellesmere Island, Canada

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