ABSTRACT: The New York-Alabama Lineament; an Early Iapetian Wrench Fault?
SHUMAKER, ROBERT C., West Virginia University
The New York-Alabama lineament, extending through the heart of the Appalachian basin, is a northeast-striking basement lineament visible on regional gravity and magnetic maps. The lineament separates north-trending gravity anomalies on the west from prevailing northeast trends. Previously interpreted as a Grenville: suture zone, fault zone and rift-related magmatic zone, it is reinterpreted as a right-lateral wrench fault that formed during an initial stage (.75Ga) of Iapetian extension which also formed graben in the Piedmont area. Truncation of basement trends indicates its post-Grenville age (.8-1.1Ga.) and utilization of the lineament by Early-Cambrian Rome trough faults (.55-.58Ga.) suggests it formed between these events, during initial breakup of Rodenia. This interpretation resolves physical relationships implied by the geophysical data.
Positions of West Gondwana and Amozonia prior to breakup and predicted subsequent rotation, based on paleo-magnetic data, support right-lateral plate offset along the eastern margin of Laurentia. The New York-Alabama lineament, near the eastern margin of Laurentia, may have formed as a sub-parallel right-slip shear zone, thus increasing the width of Grenville terrain within the central and southern Appalachians. Understanding basement tectonism is important to the search for deep hydrocarbons along the lineament.
Search and Discovery Article #90907©2000 AAPG Eastern Section Meeting, London, Ontario, Canada