Central Slave Basement Complex, Northwest Territories: its autochthonous cover, décollement, and structural topology

Abstract

A comprehensive and testable model is presented for basement/cover relationships in the south-central Slave Province. Basement rocks predating the Yellowknife Supergroup can be combined into a single basement block, the Central Slave Basement Complex. Its structural topology is described and preliminary U-Pb data are presented for a ca. 3.4-3.2 Ga gneiss below the Courageous Lake greenstone belt. All presently known occurrences of a distinctive quartzite and banded iron-formation assemblage occur immediately above the complex and are included in a new stratigraphic entity, the Central Slave Cover Group, which represents the autochthonous cover to the Central Slave Basement Complex. A regional décollement marks the contact of the basement complex and its cover with the overlying parautochthonous to allochthonous tholeiitic break-up sequence. Mutually consistent lineation data and kinematic indicators, at five widely spaced localities, suggest significant northeast-to-southwest transport of the tholeiite sequence over the basement complex and its cover sequence.