Influence of a continental promontory on time and place of orogeny
- Univ. of Kentucky, Lexington, KY (United States). Dept. of Geological Sciences
Three separate elements of the Appalachian-Ouachita orogenic belt converged on the Alabama promontory of North American continental crust during the late Paleozoic: (1) the NW striking eastern arm of the Ouachita salient along the southwest side of the promontory in eastern Mississippi; (2) the N-NE-striking southern arm of the Appalachian Tennessee salient along the northeast part of the promontory in northwestern Georgia; and (3) the NE-striking Appalachian Alabama recess along the southeast side of the promontory. The Ouachita allochthon of off-shelf deep-water facies was thrust onto autochthonous shelf-facies rocks during arc-continent collision. In contrast, thrust-imbricated shelf-facies rocks in the Appalachian Tennessee salient and Alabama recess were tectonically replaced above shallow basement rocks by accreted terranes during continent-continent collision. Ouachita synorogenic deposits indicate that collision began on the southeast during Mississippian and progressed northwestward along the continental margin during Pennsylvanian. Both the Ouachita thrust faults and synorogenic clastic wedge are truncated by northeast-striking Appalachian thrust faults in the Alabama recess. Interference patterns and footwall truncations indicate a complex succession of break-forward and break-back episodic thrusting of broadly coeval elements of the Tennessee salient and Alabama recess. Differences in structural style along the orogen indicate collision with multiple plates. The latest inception of thrusting involved the northeast-striking Alabama recess across the corner of the promontory. The frontal part of the northeast-striking Alabama recess overrode the dormant southeastern end of the Ouachita salient and mutually interfered with the still-active southern part of the Tennessee salient.
- OSTI ID:
- 5688920
- Report Number(s):
- CONF-921058--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 24:7; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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