Dip domain method applied to the Mesozoic Connecticut Valley Rift Basins

This paper presents a new approach to structural analysis of U.S. East Coast Mesozoic basins. A contoured compilation of numerical values of dip data for the Connecticut Valley rift basins reveals distinct domains related to their broader tectonic development. Additional, more standard geologic constraints are then used to interpret the dip domain patterns. Most of the tilt deformation involved and hence postdated Early Jurassic basaltic flow units and overlying Jurassic thick alluvial deposits. Normal drag characterizes the attitude of Mesozoic strata along the Western Border fault of the main Hartford basin, whereas reverse drag is common along its larger, listric, Eastern Border fault. Strata within the basin, mostly along its eastern margin, include several subgrabens and/or strongly tilted zones associated with early subbasins marked by local changes in strike of the early border fault. The Meriden cross‐graben may be a similar structure that extended much farther southwestward across the basin. Within the Hartford basin, linear domains of steeper dips are interpreted as surface expressions of the edges of a 5 to 15 km wide, late stage, Central graben that trends N15°E diagonally across the basin, possibly a reflection of very late, strike‐slip stress systems.