Structural Geometry and History
1974. "Structural Geometry and History", Geology of the Arisaig Area, Antigonish County, Nova Scotia, A. J. Boucot, J. F. Dewey, D. L. Dineley, R. Fletcher, W. K. Fyson, J. G. Griffin, C. F. Hickox, W. S. McKerrow, A. M. Ziegler
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Although possessing an apparent over-all structural simplicity, the rocks of the Arisaig area bear evidence of five phases of deformation (D1... D5), excluding faulting, and pose a number of vexing structural problems. The area is structurally bounded to the southeast by the Hollow Fault zone (Pl. 1; Fig. 16); this is probably a zone of repeated strike-slip and dip-slip movement. The highland country of Antigonish County, lying southeast of the Hollow Fault zone, is a low-grade metamorphic tract of Ordovician rocks, the Browns Mountain Group. The Hollow Fault zone appears to extend northeastward and southwestward for some miles, and it has been suggested (Wilson, 1963) that it may be part of a fundamental fault zone extending beyond the limits of Nova Scotia. Few minor folds can be seen in the area, but cleavages and lineations are well developed, and a detailed study of these has permitted a tenable structural hypothesis to be constructed.
The dominant and most persistent fold in the Arisaig area is the upward-facing Arisaig Syncline, the axial trace of which passes northeast-southwest across the southeastern part of the area (Fig. 16). Northeast of Arisaig Brook, the northern, southward-facing limb of the fold is generally overturned and the southern, northward-facing limb of the fold is gently inclined to the west, or northwest (Fig. 17). The regional fold plunge is gently to the southwest, but local, shallow, plunge-reversals occur in major parasitic folds (for example, the Doctors Brook Syncline) on the southern limb. A clear structural pattern emerges . . .