AAPG Bulletin, V. 82 (1998), No. 5A (May 1998 Part A), P. 817-835.

Diachronous Rifting, Drifting, and Inversion on the Passive Margin of Central Eastern North America: An Analog for Other Passive Margins¹

Martha Oliver Withjack,² Roy W. Schlische,³ and Paul E. Olsen⁴

©Copyright 1998.  The American Association of Petroleum Geologists.  All Rights Reserved

¹Manuscript received July 22, 1996; revised manuscript received April 25, 1997; final acceptance January 14, 1998.
²Mobil Research and Development Corporation, P.O. Box 650232, Dallas, Texas 75265-0232.
³Department of Geological Sciences, Wright Labs, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854-8066.
⁴Lamont-Doherty Earth Observatory of Columbia University, RT 9W, Palisades, New York 10964-8000.

We thank Mobil Research and Development Corporation for permission to publish this work. We also thank Rolf Ackermann, Jim Carpenter, Cynthia Ebinger, Gloria Eisenstadt, Jack Howard, Charles Kluth, and C. Wylie Poag for reviewing this and earlier versions of the manuscript. Research by RWS was supported by grants from the Rutgers University Research Council and Mobil Research and Development, and PEO acknowledges support from the National Science Foundation (ATM93-17227) and LDEO. This is Lamont-Doherty Earth Observatory Contribution #5655. 

ABSTRACT

Integration of new data with existing information indicates that the tectonic development of the passive margin of eastern North America between the Carolina Trough and Scotian Basin was considerably more complex than the classic two-stage, rift-drift model. First, the transition from rifting to drifting was diachronous. In the southeastern United States, the rift-drift transition occurred after the Late Triassic synrift deposition and before eastern North America magmatism in the earliest Jurassic (~200 Ma). In maritime Canada, the rift-drift transition occurred after eastern North America magmatic activity and synrift deposition in the Early Jurassic and before postrift deposition in the early Middle Jurassic (~185 Ma). Second, the deformational regime changed substantially after rifting on both the southern and northern segments of the margin. Generally, northwest-southeast postrift shortening replaced northwest-southeast synrift extension. Northeast-striking reverse faults formed, and many of the rift-basin boundary faults had reverse displacements. In the southeastern United States, the change in the deformational regime occurred in the Late Triassic-Early Jurassic during the rift-drift transition. Simultaneously, diabase sills and dikes, many striking nearly perpendicular to the trend of the rift basins, intruded the continental crust; and a massive wedge of volcanic or volcaniclastic rocks developed near the continent-ocean boundary. In maritime Canada, the change in the deformational regime occurred during or after the Early Jurassic and before or during the Early Cretaceous; that is, during the rift-drift transition or early stages of sea-floor spreading.