Determining the provenance of Triassic sedimentary rocks in northeastern British Columbia and western Alberta using detrital zircon geochronology, with implications for regional tectonics

Abstract

Triassic rocks of the Western Canada Sedimentary Basin (WCSB) have previously been interpreted as being deposited on the passive margin of North America. Recent detrital zircon provenance studies on equivalent Triassic rocks in the Yukon have suggested that these rocks were in part derived from the pericratonic Yukon–Tanana terrane and were deposited in a foreland basin related to the Late Permian Klondike orogeny. Detrital zircons within a number of samples collected from Triassic sediments of the WCSB throughout northeastern British Columbia and western Alberta suggest that the bulk of the sediment was derived from recycled sediments of the miogeocline along western North America, with a smaller but significant proportion coming from the Innuitian orogenic wedge in the Arctic and from local plutonic and volcanic rocks. There is also evidence of sediment being derived from the Yukon–Tanana terrane, supporting the model of terrane accretion occurring prior to the Triassic. The age distribution of detrital zircons from the WCSB in British Columbia is similar to those of the Selwyn and Earn sub-basins in the Yukon and is in agreement with previous observations that sediment deposited along the margin of North America during the Triassic was derived from similar source areas. Together these findings support the model of deposition within a foreland basin, similar to the one inferred in the Yukon. Only a small proportion of zircon derived from the Yukon–Tanana terrane is present within Triassic strata in northeastern British Columbia, which may be due to post-Triassic erosion of the rocks containing these zircons.

A Late Jurassic to Early Cretaceous record of orogenic wedge evolution in the Western Interior basin, USA and Canada

“…Therefore, to preserve Mesozoic-dominated detrital zircon spectra in the foreland, rivers that supplied sediment to the Western Interior basin from the magmatic hinterland would need to have traversed the fold-thrust belt without incorporating detrital zircon grains from pre-foreland sedimentary strata, which in aggregate yield diverse detrital zircon spectra (Fig. 7) (Ross and Villeneuve, 2003;Dickinson and Gehrels, 2009b;May et al, 2013;Gehrels and Pecha, 2014;Golding et al, 2015). Aerial delivery of Early Cretaceous zircon to the basin is possible or even probable; however, most of the zircon in these samples is Jurassic in age, supporting an interpretation that fluvial sediment routing was an important process (Figs.…”

Controlling factors on source rock development: implications from 3D stratigraphic modeling of Triassic deposits in the Western Canada Sedimentary Basin

“…10) suggests an expansion of the drainage areas from the continent (Fig. 15) (Golding et al, 2015a). At the transition between sequence A and B, a sharp drop of water discharge and sediment supply suggest a significant reduction of the continental drainage area to the east (Millman and Syvitski, 1992).…”

U-Pb isotopic ages of euhedral zircons in the Rhaetian of British Columbia: Implications for Cordilleran tectonics during the Late Triassic

“…Regional provenance studies of Triassic sediment deposited on the North American margin in Canada have previously recognized that this sediment was derived not just from the North American craton to the east, but also from the Arctic and from the pericratonic Yukon-Tanana terrane to the west (Ross et al, 1997;Ferri, 2009;Beranek et al, 2010;Ferri et al, 2010;Golding et al, 2016). Close ties between the Yukon-Tanana and Quesnel terranes have been postulated (see preceding), consistent with the terranes being situated close to one another during the Late Triassic.…”

“…The youngest ages were all obtained from very small grains for which it was impossible to avoid analyzing material near the grain margins; therefore, it is quite likely that the material analyzed in these grains may have undergone some degree of Pb loss. The euhedral grains in the sample from Black Bear Ridge are interpreted to be first cycle due to their shape and age; it is well documented that reworked detrital zircons from the Triassic of British Columbia are moderately to well rounded, and none have been dated as younger than Permian (Ross et al, 1997;Beranek et al, 2010;Golding, 2014;Golding et al, 2016).…”

“…As part of a larger study on the provenance of Triassic sediments in northeastern British Columbia (Golding, 2014;Golding et al, 2016), samples were collected for detrital zircon analysis from the Rhaetian (uppermost Triassic; Fig. 2) portion of the section at Black Bear Ridge on Williston Lake (Fig.…”