Provenance and Depositional History of the McAras Brook Formation, Antigonish County, Nova Scotia

Abstract

The McAras Brook Formation was deposited in the Merigomish Structural Basin during the upper Mississippian. The lower conglomeratic member was deposited by alluvial fans. The detritus accumulated along both sides of the fault-bounded basin. Periods of basement instability are reflected by basalt flows present in the lower member. Movement of the Hollow Fault caused a major change in the drainage pattern. A fluvial system advanced over the alluvial fan at the type section. The fault movement causing this may have been the southern Antigonish Massif rising while the northern section sank. The fluvial system flowed over this sunken area.

During deposition of the lower member at the type section, the Knoydart Formation was exposed to the south of the Hollow Fault. The Browns Mountain Group became exposed during deposition of the Knoydart Brook section. The upper strata of the Browns Mountain Group was predominantly green quartzite during the Mississippian. These units have been completely eroded since Mississippian time. Browns Mountain lithologies present during the Carboniferous at the tip of Cape George were of the same lithologies as those outcropping today.

Keywords: Pages: 80 Supervisor: Paul Schenk