Stratigraphy and structure of the Horton Group, Lochaber-Mulgrave area, northern mainland Nova Scotia

Paul J. Ténière, Sandra M. Barr, Chris E. White
2005 Atlantic geology  
The Lochaber-Mulgrave area of northern mainland Nova Scotia is underlain by rocks of the Late Devonian -Early Carboniferous Horton Group, in faulted contact with older Devonian and Silurian rocks to the south and west, and younger Carboniferous rocks to the north and east. The Horton Group is divided into (from oldest to youngest) the Clam Harbour River, Tracadie Road, Caledonia Mills, and Steep Creek formations, with a total thickness of at least 4000 m. These units were deposited in a variety
more » ... of braided fl uvial and shallow to deep lacustrine environments, and show lithological and stratigraphic similarities to the Horton Group elsewhere in Nova Scotia. Sparse palaeontological data from macrofossils and spores indicate an age range from Famennian to late Tournaisian. Compared to elsewhere in Nova Scotia, the Horton Group in the Lochaber-Mulgrave area is more deformed and metamorphosed, especially in the southern part of the area near the Roman Valley Fault. The time of regional deformation and metamorphism is constrained to ca. 340-335 Ma by whole-rock 40 40 Ar/ 39 39 Ar dating of slate in the Clam Harbour River and Tracadie Road formations. Regional deformation and metamorphism may have resulted from burial by older rocks of the Guysborough block, thrust over the Horton Group in the Lochaber-Mulgrave area from the south as a result of transpression at a restraining bend along the Chedabucto-Roman Valley fault system during juxtaposition of the Avalon and Meguma terranes.
doi:10.4138/658 fatcat:gwnjvmwefnhovoy6bac5aaltui