Some comparisons of the structure and evolution of the southern Appalachian-Ouachita orogen and portions of the Trans-European Suture Zone region

Many aspects of the tectonic history of the Appalachian-Ouachita orogen and the Trans-European suture region are similar. In a tectonic sense, they ar e geographically linked, because at the end of the Paleozoic, one could tra vel from Texas to Poland following a continuous orogenic belt. Much of each of these orogenic belts is, however, buried by younger strata, and thus ge ophysical studies are a key element of efforts to better understand them. M any more geophysical data are needed to provide a comprehensive picture of the deep structure, but in several areas new models of the lithospheric str ucture are emerging. In this paper, we review some of these models and intr oduce two new ones for the southern Appalachians. In addition, we explore t he implications of these models for the evolution of these orogenic belts, drawing attention to similarities and differences in their structure and ev olution. The Appalachian and Caledonian orogens represent temporally parall el development along irregular Late Proterozoic continental mal:gins, but t he crustal structure is different because of different accretionary element s and complications in the geometry of the original margins. Lateral transp ort via thrusting can confuse efforts to tie geologic structures identified on the surface with deep structures. For example, in the Appalachian-Ouach ita orogen, the thrust-related transport distance for major features such a s the Blue Ridge-Piedmont sheet and the Benton uplift is at least 200 km, O n a crustal scale, deformation in the Appalachian-Ouachita orogen varies gr eatly in style and intensity. In the Ouachita orogen, the Late Proterozoic continental margin seems to be preserved, while in the northern Appalachian s crustal-scale deformation is intense. Along the US Appalachians, the majo r crustal structure variation is the thin, dense crust of Avalonia abutting the relatively thick crust of Laurentia. Along the Ouachita orogen, severa l large crustal blocks can be identified that are unlike anything seen alon g the Appalachians. (C) 1999 Elsevier Science B.V. All rights reserved.