Evidence for Dominance of Normal Dip-Slip Motion on Segment of Flemington Fault in Newark Basin of New Jersey: ABSTRACT

Abstract

A fracture study conducted on a series of outcrops along U.S. Route 202, beginning approximately 1.5 km east of the Delaware River and extending eastward for a distance of approximately 1.5 km, provides ample evidence for normal dip-slip faulting and virtually no evidence of strike-slip faulting. The study area is located approximately 1 km south of the Dilt's Corner fault, the southern splay of the Flemington fault, and along a line nearly perpendicular to the axis of a broad, open anticline plunging approximately 10°S, 20°E. This anticline is one of several transverse folds on the hanging-wall side of the Flemington-Dilt's Corner fault system. Measurement of more than 150 small faults revealed fewer than 10 with a significant strike-slip component of motion. Most of the small faults in the area strike northeasterly and dip steeply either to the northwest or to the southeast. Of particular interest are faults that strike N40°E and dip approximately 70° to the northwest or southeast. These faults appear to define a conjugate set, and as such would require ^sgr1 to be nearly vertical, ^sgr2 to be horizontal and trending N40°E, and ^sgr3 to be horizontal and trending S50°E. In 1962, Sanders suggested that in addition to considerable dip-slip displacement, the Flemington fault might have a major right-lateral strike-slip component of motion. Manspeizer used right-lateral strike-slip motion on the Flemington fault as part of his rhomb-graben model for the Newark basin. Recently, Burton and Ratcliffe have suggested that the Flemington fault has both right-lateral and normal components of motion on it. Strike-slip motion, at least on the Dilt's Corner splay of the Flemington fault, is not compatible with the observed field data. End_of_Article - Last_Page 1438------------