Depositional environment and provenance of Early Carboniferous clastic sedimentary rocks at McIsaacs Point, Nova Scotia: implications for syntectonic basin development during the formation of Pangaea

Abstract

Abstract Following the collision of Gondwana and Laurussia to form Pangaea, a large system of regional-scale strike-slip faults developed which resulted in the formation of transtensional syncollisional basins. One such basin, the Antigonish Basin, contains late Devonian fluvial, marine and lacustrine sedimentary rocks, including sandstone, conglomerate and shale. LA-ICP-MS U–Pb detrital zircon data from three samples from the lower and middle of the McIsaacs Point section have a strong Silurian–Devonian ( c. 440–380 Ma) population whereas the top of the section lacks these age populations and is instead dominated by Neoproterozoic ( c. 630–550 Ma) grains. Detritus was derived from a mix of local Avalonian and more distal Meguma terrane sources. Detrital zircon and field data show that sediments were deposited in a braided to meandering fluvial system transitional to a proximal braided stream environment followed by evolution to a more distal braided stream environment. As the basin evolved, the source of detritus shifted from a dominantly Meguma terrane source to a more local Avalonian source. This temporal evolution in provenance and depositional environment attests to the complex depositional processes associated with syntectonic basin evolution during the formation of Pangaea.