POST-FAULTING DEFORMATION OF THE LAKE CHAR-HONEY HILL FAULT, SOUTHEASTERN CONNECTICUT

The Lake Char-Honey Hill Fault in southeastern Connecticut has a curved map trace composed of two faults: the north-south trending Lake Char and the east-west trending Honey Hill Fault. These two faults meet and conjoin around a sharp 90° bend north of Ledyard, Connecticut. In order for motion to be possible on this fault in its current geometry, the lineations should be approximately parallel around the trace of the fault.

Detailed meso- and microstructural analysis of foliations and lineations in mylonitic rocks around the fault bend suggests syn- or post-faulting tightening of the bend, as well as accommodation of slip along a curved, spoon-shaped surface. On the Lake Char portion of the fault the foliation strikes generally north to northwest (165, 52), and the lineation trends west-northwest (294, 35). On the Honey Hill portion of the fault, the foliation strikes generally west-northwest (310, 30), and the lineation trends north-northwest (335, 16). In the middle of the bend, within the Preston Gabbro, the foliation strikes northwest (299, 57), and the lineation trends northwest (304, 7).

The systematic variation in the orientation of the lineation around the bend in the fault suggests syn- or post-faulting tightening of the bend. Geometric analysis of the lineation orientations suggests a NW-SE trending fold axis, with multiple possible plunges. Unfolding the foliation orientations yields a pre-folding geometry for the trace of the fault, which more closely resembles that of low-angle detachment faults in the Basin and Range province. These observations suggest that the Lake Char-Honey Hill fault may have formed as a curved surface and was locally tightened to its present orientation by NE-SW directed shortening during or after faulting.