4 Sedimentary Systems and Provenance in the Western Cordillera

This session invites contributions on sedimentary processes, depositional environments, stratigraphic frameworks, and provenance evolution across western North America. Topics may include basin analysis, source-to-sink studies, and applications of stratigraphy to energy and environmental questions.

Wednesday, 22 April 2026
8:00 AM - 12:00 PM
LMH, Fiesta Terrace Salon

Detrital Zircon U-Pb Geochronology of the Late Devonian Earn Group: Implications for paleodrainage reorganization in northern Canada during renewed subduction

Paper number: 4-2
Program: Technical Sessions
Time: 8:25 AM – 8:45 AM

Authors

Abstract

The Late Devonian–Early Mississippian marks the onset of subduction-related processes and assembly of the accretionary margin in northwestern Canada. During this time, eastward subduction of Panthalassa oceanic crust beneath northwestern Laurentia generated an extensional back-arc system, separating the Yukon-Tanana terrane from the continent as the Slide Mountain Ocean opened. Back-arc extension in the upper crust renewed subsidence along the continental margin, resulting in deposition and Zn-Pb mineralization of coarse clastic marine rocks of the Earn Group in the Selwyn Basin in present-day Yukon Territory, Northwest Territory, and northern British Columbia. Despite its tectonic and economic significance, the sediment provenance and paleogeographic origin of these back-arc basin strata remain poorly understood due to sparse data. We present new detrital zircon U-Pb geochronology results from the Earn Group collected along strike of the paleo-continental margin in the Yukon Territory and northern British Columbia to resolve paleodrainage reorganization of in response to this tectonic shift. Dominant age populations at 1.4–1.1 Ga, 2.0–1.8 Ga, and >2.5 Ga reveal a diverse provenance signature inconsistent with derivation solely from local continental margin strata, as previous studies propose. Instead, ages share a similar source signal to clastic wedge strata derived from mid–late Paleozoic Arctic orogenic belts (i.e. Franklinian, Ellesmere, Innuitian), suggesting that paleodrainage networks supplying the Selwyn Basin may have extended further northeast into the paleo-Arctic realm.

Geological Society of America Abstracts with Programs. Vol. 58, No. 3

doi: 10.1130/abs/2026CD-410978

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