Chemostratigraphy of neoproterozoic carbonate units in the Northern Selwyn Basin, Yukon

Abstract

The correlation of Selwyn basin stratigraphy with platformal sequences of the upper Windermere Supergroup has been a topic of study for many decades. The strata of the Windermere Supergroup are thought to represent a Neoproterozoic transition to passive margin sedimentation from an active rift system. The oldest strata of the Selwyn basin, the Hyland Group, are the initial product of this pericratonic passive margin sedimentation. Recent mapping at the eastern extent of the Dawson fault zone at the northern boundary of the Selwyn basin indicates equivalence of the Algae and Narchilla formations (Hyland Group – Selwyn basin) with the Risky and Ingta formations (‘upper group’ – Windermere Supergroup). To further substantiate this equivalence two Hyland Group carbonate markers in the Selwyn basin have been compared with well-studied strata of the Windermere Supergroup from north of the Dawson fault. Specifically, through detailed comparison of sedimentological, chemostratigraphic, and petrographic characteristics, this study aims to correlate the upper carbonate marker (Algae Formation) and the lower carbonate marker (part of the Yusezyu Formation) with the Risky Formation and Gametrail Formation of the Windermere Supergroup, respectively. The Gametrail Formation displays a distinct isotopic signature suggestive of the ~580 Ma Shuram/Wonoka anomaly and thus confirming these stratigraphic relationships across the Dawson fault would begin to suggest the deposition of the Hyland Group stratigraphy along with final rifting of the NW Laurentian margin occurred during the late Ediacaran.