--> Abstract: The Structural Development of Aulacogens in England, Utah and the Southern USA, by N. J. P. Smith, K. Smith, and A. W. A. Rushton; #90942 (1997).

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Abstract: The structural development of aulacogens in England, Utah and the southern USA

SMITH, N J P, K SMITH and A W A RUSHTON

The Variscan foldbelt stretches across the whole of Europe from the Urals, in the east, to Eire, Iberia and Morocco, in the west. In the USA it forms the Southern Appalachians and the Ouachitas and extends, largely in the subsurface, from Alabama to the borders of northern Mexico. The entire length of this late Paleozoic orogen has a remarkably similar tectonic and stratigraphic history. The structural evolution of two segments of the foldbelt, where aulacogens impinge, in England and southern USA, defines a model. Also structurally similar are the late Paleozoic Ancestral Rockies and the Laramide Central Rockies basement uplifts of Wyoming, Colorado and Utah. Here aulacogens, notably the Uinta Mountains of Utah, which formed as a Precambrian rift adjoining the Cordilleran foldbelt, were inverted during the Laramide Orogeny.

In all these areas aulacogens connect two differently aged foldbelts. We relate the structural development of the aulacogens to plate tectonic movements, which led to closure of oceans and continental collisions in the coeval fold belts. Comparison of the aulacogens with some of the Permo-Triassic rift basins of NW Europe suggests that the same structural relationships exist here, waiting for the Atlantic Ocean to close. The Permo-Triassic Worcester Graben in England has precisely reactivated the earlier Paleozoic aulacogen.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria