Volcano-sedimentary processes operating on a marginal continental arc: theArchean Raquette Lake Formation, Slave Province, Canada

The 200-m thick, volcano-sedimentary Raquette Lake Formation, located in th e south-central Archean Slave Province, represents a remnant are segment fl oored by continental crust. The formation overlies the gneissic Sleepy Drag on Complex unconformably, is laterally interstratified with subaqueous mafi c basalts of the Cameron River volcanic belt, and is considered the proxima l equivalent of the turbidite-dominated Burwash Formation. A continuum of e vents associated with volcanism and sedimentation, and controlled by extens ional tectonics, is advocated. A complex stratigraphy with three volcanic a nd three sedimentary lithofacies constitute the volcano-sedimentary success ion. The volcanic lithofacies include: (1) a mafic volcanic lithofacies com posed of subaqueous pillow-pillow breccia, and subaerial massive to blocky flows, (2) a felsic volcanic lithofacies representing felsic flows that wer e deposited in a subaerial environment, and (3) a felsic volcanic sandstone lithofacies interpreted as shallow-water, wave- and storm-reworked pyrocla stic debris derived from explosive eruptions. The sedimentary lithofacies a re represented by: (1) a conglomerate-sandstone lithofacies consistent with unconfined debris flow, hyperconcentrated flood flow and talus scree depos its, as well as minor high-energy stream flow conglomerates that formed coa lescing, steep-sloped, coarse-elastic fan deltas, (2) a sandstone lithofaci es, interpreted as hyperconcentrated flood flow deposits that accumulated a t the subaerial-subaqueous interface, and (3) a mudstone lithofacies consis tent with suspension sedimentation in a small restricted lagoon-type settin g. The Raquette Lake Formation is interpreted as a fringing continental are that displays both high-energy elastic sedimentation and contemporaneous e ffusive and explosive mafic and felsic volcanism. Modern analogues that dev elop along active plate margins in which continental crust plays a signific ant role include Japan and the Baja California peninsula. (C) 2001 Elsevier Science B.V. All rights reserved.