Alleghanian paleostress reconstruction in the northern Appalachians: Intraplate deformation between Laurentia and Gondwana

摘要

A numerical paleostress tensor analysis using striated fault planes has been conducted in the Quebec reentrant of the northern Appalachians to characterize the stress field of late Paleozoic deformations. Three directions of maximum compressional stress axes (s1) have been found and correlated to (1) an early north-northwest-south-southeast compression, (2) a north-northeast-south-southwest compression, and (3) a late west-northwest-east-southeast compression. Fault populations associated with these stress regimes are present in all tectonic zones of the Québec and northern New Brunswick Appalachians. Directions of 1 axes determined in the northern Appalachians resemble in orientation and in relative chronology layer-parallel shortening fabrics and joint patterns found in the Appalachian foreland of the central Appalachians. The paleostress regimes are interpreted as the record of intraplate deformation related to the indentation of Gondwana into Laurentia during the late Paleozoic Alleghanian orogeny.