CHARACTERIZATION OF FLOWS AND DIKES IN NORTHFORD, CT

In the complex-faulted area south of Northford, CT, outcrops of Talcott basalt and Fair Haven diabase dikes can be differentiated on the basis of morphology and field observations; according to fieldwork initiated in the summer of 2002. Dikes can be characterized by: coarse grain size, blocky rectangular joints, chill margins, and vesiculation. In contrast, flows exhibit: variable grain size, horizontal or platy jointing, autobrecciation, vesicular tops and bases, amygdules and secondary mineralization, bulbous morphology and or pahoehoe toes. Follow-up trace element geochemistry helps to establish differences between the units and affinities between feeder dikes and associated flows. The presence of and degree of vesiculation within dike segments suggests near surface emplacement.