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A Lower Carboniferous Two-Stage Extensional Basin Along The Avalon-Meguma Terrane Boundary: Evidence From Southeastern Isle Madame, Nova Scotia, Eric R. Force, Sandra M. Barr

Eric R Force

ABSTRACT Anomalously thick and coarse clastic sedimentary successions, including over 5000 m of conglomerate, are ex- posed on Isle Madame off the southern coast of Cape Breton Island. Two steeply to moderately dipping stratigraphic packages are recognized: one involving Horton and lower Windsor groups (Tournasian–Visean); the other involving upper Windsor and Mabou (Visean–Namurian) groups. Also anomalous on Isle Madame are three long narrow belts of “basement” rocks, together with voluminous chloritic microbreccia and minor semi-ductile mylonite, which are separated from the conglomerate-dominated successions by faults. The angular relations between the cataclastic rocks and the conglomerate units, combined with the presence …