15 Structural Geology and Tectonics

Thursday, 5 April 2001
1:00 PM - 5:00 PM

IMPLICATIONS OF A PALINSPASTIC MAP FOR THE STRATIGRAPHIC AND TECTONIC FRAMEWORK OF THE ALABAMA-GEORGIA APPALACHIAN THRUST BELT

Paper number: 15-1
Program: Technical Sessions
Time: 1:00 PM – 1:20 PM

Authors

Abstract

A palinspastic map of the Alabama-Georgia Appalachian thrust belt illustrates: (1) restoration of mushwad areas; (2) location and lateral continuity of the Rome thrust sheet (RTS); (3) lateral continuity of the Coosa (CTS) and Helena (HTS) thrust sheets; and (4) role of basement faults in stratigraphy and thrust-belt geometry. To test the palinspastic map, the lateral continuity of restored thrust sheets is examined through comparison of the distribution of different stratigraphic intervals using tectono-stratigraphic criteria. As a result, present continuity of thrust sheets does not necessarily imply lateral continuity of palinspastic positions.

Important implications are: (1) Cambrian-Ordovician successions restoring within and southeast of the Birmingham graben (BG) record inversion of the BG. BG faults and thick Conasauga weak rocks controlled subsequent geometry of Alleghanian structures. (2) The RTS restores southeast of the HTS and ends laterally as a shallow structure. An Upper Ordovician clastic succession, now partitioned by the RTS, restores as a continuous belt. Restored Conasauga stratigraphy of the BG, HTS, and RTS indicates a separate graben southeast of the restored HTS. (3) The CTS is a composite of two originally non-continuous thrust sheets. Cambrian-Ordovician stratigraphy west of a north-striking fault in Alabama implies continuity with the HTS, whereas coeval stratigraphy to the east resembles the stratigraphy of the CTS in Georgia. (4) The trailing edge of the southeasternmost thrust sheets restores near the present position of the Pine Mountain terrane (PMT), indicating that the Talladega Slate Belt restores southeast of the PMT.