Archaean sedimentary sequences of the Slave craton

Abstract

The Slave Craton is composed of five Archaean terranes that accreted during the Neoarchean. The Central Slave superterrane is the only tectonic block containing evidence of four major sedimentary successions, including 1) a quartz arenite-dominated succession deposited on an extensive tide-influenced coastline along a rifted continental margin, 2) a turbidite-dominated succession that developed as submarine fans in a fore-arc or intra-arc basin, 3) a second turbidite succession representing deep water deposition in a back-arc basin, and 4) late conglomerate-dominated successions representing fluvial, alluvial fan and shallow water depositional settings in strike-slip basins. Deposition of the sedimentary rocks took place between ca. 3.1 Ga and 2.6 Ga, indicating a complex tectonic history. An unconformity between the gneissic basement and the overlying quartz arenite succession marks a marine flooding surface consistent with a first order sea level change. A major hiatus lies between the quartz arenite successions and arc-backarc related volcanic deposits with interstratified and conformably overlying turbidite strata. Late conglomerate successions are exposed along north-trending lineaments and overlie all sedimentary and volcanic rock units unconformably. This depositional hiatus represents a fundamental change from compression and uplift to transcurrent motion during the final stages of craton stabilization. Between ca. 2630 and 2580 Ma, the Slave Province experienced considerable pluton emplacement, which disaggregated much of the once-continuous stratigraphy. A Wheeler diagram illustrates the major tectonic events that occurred during formation of the Central Slave superterrane, however, remaining uncertainties concerning the evolution of the entire Slave craton reflect the need for additional detailed field investigations.