Open AccessOverlap assemblages: Laberge Group of the Whitehorse Trough, northern Canadian Cordillera
Author(s) -
Dawn A. Kellett,
A Zagorevski
Publication year - 2021
Language(s) - English
Resource type - Reports
DOI - 10.4095/326064
Subject(s) - geology , zircon , terrane , cretaceous , paleontology , back arc basin , clastic rock , group (periodic table) , thermochronology , siliciclastic , structural basin , sedimentary depositional environment , tectonics , subduction , chemistry , organic chemistry
The Laberge Group was deposited during the Early to Middle Jurassic in a marginal marine environment, in the northern Canadian Cordillera. It occurs as a narrow, elongated siliciclastic unit along more than 600 km of strike length, overlapping the Intermontaneterranes of southern Yukon and northwestern British Columbia. The Laberge Group was deposited on the Late Triassic Stuhini and Lewes River groups, a volcano-plutonic complex of the Stikine terrane (Stikinia), and, locally, the Kutcho Arc. It is overlain by Middle Jurassic to Cretaceous clasticunits. The variations in clast composition and detrital zircon populations among these units indicate major changes in depositional environment, basin extent, and sources during the latest Triassic to Middle Jurassic. Detrital zircon populations are dominated by near contemporary Stuhini-Lewes Riverarc grains, consistent with dissection of an active arc. Detrital rutile and muscovite data show rapid cooling and exhumation of metamorphic rocks during the Early Jurassic. Thermochronological data indicate that basin thermal evolution was domainal, with at least five regional temperature-timehistories.