EVIDENCE FOR THE POST-ALLEGHANIAN BUNKER HILL FAULT ZONE AND Z FAULT IN THE EASTERN HIGHLANDS OF SOUTH-CENTRAL CONNECTICUT USING LIDAR AND GEOMORPHIC DATA INTEGRATED WITH FIELD INVESTIGATIONS

LiDAR data from south-central Connecticut revealed a 14-km-long, NW-trending zone of en échelon lineaments that traverse the Killingworth dome along a previously mapped continuous fault on the State geological map of Connecticut. These lineaments coincide with linear stream valleys that we believe represent erosion along brittle faults that we have collectively named the Bunker Hill fault zone (BHFZ). Collinear LiDAR lineaments to the northwest suggest that the BHFZ extends ~4 km northwestward across the Eastern border fault and part of the Jurassic-age Portland Formation of the Hartford rift basin. Toward the southeast, the BHFZ dextrally offsets the Higganum dike system (HDS) ~600 m. The BHFZ truncates the Eastford lineament, a regional feature that appears to be the SW extension of the Eastford fault that we interpreted from LiDAR and topographic lineaments (see Altamura and others elsewhere in this volume).

The LiDAR data also revealed a ~7-km-long, nearly EW-trending zone of en échelon lineaments southwest of the BHFZ that coincides with discontinuous topographic depressions and small scarps, and a 1.2-km-wide, left-stepping pattern along the contact between the Ordovician-age Monson and Middletown gneissic formations. Detailed field mapping of foliation strike and dip patterns north and south of this zone revealed that the dip of the two formations abruptly steepens 30-40° north of the left-stepping pattern. Based on these observations, we postulate that this zone of LiDAR lineaments is a fault that we have tentatively named the Z fault.