Carbonate sedimentation in an extensional tectonic regime: the Lower Devonian Upper Gaspé Limestones, Quebec Appalachians
Carbonate sedimentation occurred over most of eastern Gaspe Peninsula in Early Devonian time. The resulting succession, known as the Upper Gaspe Limestones, is a 500–1800 m thick unit outcropping in the Connecticut Valley – Gaspe Synclinorium. Detailed stratigraphic and sedimentologic work allows recognition of important thickness and lithofacies variations in a north–south-oriented transect in the eastern part of the peninsula. Variations are spatially associated with Acadian (Middle Devonian) dextral strike-slip faults. Three lithotectonic domains are proposed and interpreted; they are, from north to south, (1) a proximal outer shelf, (2) a distal, gently sloping outer shelf, and (3) a slope or slope toe. Field mapping and reinterpretation of seismic profiles from this area have shown that the faults bounding the three domains are reactivated normal listric faults. Early Devonian vertical movement along these faults caused accelerated subsidence of the central and southern segments of the sedimentary ba...