FAULT SEQUENCING WITHIN THE SOUTHERN HARTFORD BASIN, NORTHFORD, CT

Field work initiated during the Summer of 2002 in an area located within the Gaillard Graben, approximately 3-4 miles from the Eastern Border Fault, resulted in the delineation of 3 main normal fault populations. One is synthetic and two are antithetic to the Eastern Border Fault. The orientations of these populations are: northwest-southeast (331°), north-south (358°), and northeast-southwest (50°). The first faults of the sequence are northwest-southeast (331°) trending faults, which have down-dropped Shuttle Meadow clastics and carbonates against basal Talcott basalt and New Haven sedimentary sequences in the Barberry Ridge area. These northwest-southeast (331°) fault-bounded blocks terminate against north-south (358°) trending faults. These are, in turn, terminated by the final fault set which is oriented northeast-southwest (50°), dipping towards the Southeast. Faulting in this area is the result of brittle failure adjustment along the margins of the Gaillard Graben. Evidence for faulting was primarily based on field mapping. Fault identification was based on the following parameters: 1) Termination of units and/or of geomorphic features, 2) Change in lithology, 3) Steepening of dips, and 4) Sag pond presence.