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

作者：Johnson Benjamin G; Strauss Justin V; Toro Jaime; Benowitz Jeff A; Ward William P; Hourigan Jeremy K

来源：Lithosphere, 2016, 8(6): 649-667.

DOI：10.1130/L533.1

The Arctic Alaska terrane of northern Alaska and Yukon is one of several exotic terranes in the North American Cordillera with putative early Paleozoic connections to the northern Caledonian-Appalachian orogen. The U-Pb and Ar-40/Ar-39 isotopic data from detrital minerals in pre-Mississippian sedimentary units of the northeastern Brooks Range are presented here to investigate the consequences of Caledonian orogenesis on sediment dispersal trends and the paleogeography of northern Laurentia. Neoproterozoic-Cambrian siliciclastic rocks of the informal Firth River group and the Neruokpuk Formation were most likely deposited along a passive margin that sourced Archean and Paleoproterozoic basement rocks of the Canadian shield and reworked Mesoproterozoic and younger sedimentary units. These strata are overlain by a Lower Ordovician-Lower Devonian succession of fine-grained siliciclastic turbidites, herein referred to as the Clarence River group, which records a prominent shift in provenance most likely associated with the onset of the Caledonian-Appalachian orogeny in northeast Laurentia. U-Pb detrital zircon age populations of ca. 470-420 and 990-820 Ma, along with Ar-40/Ar-39 detrital muscovite ages of ca. 470-430 Ma, support provenance connections with the East Greenland Caledonides, Pearya, and Svalbard. Partially reset Ar-40/Ar-39 ages in these sedimentary successions are linked to low-grade metamorphism associated with the Early-Middle Devonian Romanzof orogeny, a poorly understood tectonic event in the Brooks Range that is possibly associated with the emplacement of an allochthonous oceanic assemblage, herein named the Whale Mountain allochthon.

• 出版日期2016-12