Abstract

Analysis of tectonic subsidence permits calculation of the magnitude of tectonic processes and associated climatic effects, which controlled changes in sea level during deposition of Pennsylvanian cyclothems. Far-field tectonic effects in response to regional orogenic movements influenced Pennsylvanian sea-level change in the Midcontinent of North America and the Illinois basin. Organization of Virgilian and Missourian Midcontinent cyclothems into fourfold to fivefold bundles shows that sea-level changes in Midcontinent platform areas were influenced partly by Milankovitch orbital parameters, whereas Desmoinesian sea-level change apparently was influenced more strongly by tectonic subsidence. Sea-level change associated with cyclothems in the Central Appalachian basin and the Asturias basin of Spain were controlled mostly by foreland-basin subsidence and later strike-slip faulting. Methods developed herein permit calculation of magnitudes of both tectonic and glacio-eustatic components of sea-level change influencing Pennsylvanian cyclothem deposition and may be applicable to other cyclic sequences.

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