ALLEGHANIAN PALEOSTRESS RECONSTRUCTION IN THE NORTHERN APPALACHIANS -INTRAPLATE DEFORMATION BETWEEN LAURENTIA AND GONDWANA

A numerical paleostress tensor analysis using striated fault planes ha s 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 (sigma 1) have been f ound and correlated to (1) an early north-northwest-south-southeast co mpression, (2) a north-northeast-south-southwest compression, and (3) a late west-northwest-east-southeast compression. Fault populations as sociated with these stress regimes are present in all tectonic zones o f the Quebec and northern New Brunswick Appalachians. Directions of al 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 Appalachian s. The paleostress regimes are interpreted as the record of intraplate deformation related to the indentation of Gondwana into Laurentia dur ing the late Paleozoic Alleghanian orogeny.