--> ABSTRACT: Tectonic Control on Stratigraphic Sequences deposited in the Taconic Foredeep, by C. E. Mitchell, R. D. Jacobi, M. P. Joy, and D. Goldman; #91021 (2010)

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Tectonic Control on Stratigraphic Sequences deposited in the Taconic Foredeep 

MITCHELL, C. E., R. D. JACOBI, M. P. JOY, and D. GOLDMAN


Several recent interpretations of the Middle Ordovician succession in the central and southeastern U.S. posit the existence of a series of stratigraphic sequences and parasequences. Similarly, rocks of the Taconic foredeep in New York State exhibit a series of unconformity-bounded, pulsed shallowing-up cycles that, within available biostratigraphic resolution, are synchronous with those identified elsewhere. For instance, the Sugar River Limestone of the lower Trenton Group may correspond to transgressive systems tract deposits of the MS Sequence and are laterally equivalent in part to a marine hiatus and maximum flooding surface within the deep basin. The overlying highstand deposits (Denmark Formation) include a series of four parasequences that can be correlated precisely with carbonate/clastic cycles in the offshore Flat Creek Shale based on K-bentonite time lines and graphic correlation. However, patterns of facies distribution and rock accumulation rates reveal major contributions from local growth faulting to cycle and unconformity development. Similar fault controlled features of the bounding unconformities suggest that the Taconic basin succession primarily records a history of tectonically driven basin flexure rather than eustatic sea level changes. If flexural forcing in New York is correct, it raises questions about the eustatic origin of the sequences elsewhere. This interpretation can be tested by expansion of the K-bentonite chronostratigraphic framework to regions in eastern North America that experienced lithospheric flexure at different times during the Taconic Orogeny.  

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.