Small-Scale Structures as Signatures for the Tectonic History of the Fundy Rift Basin, Maritime Canada

J. A. Elder Brady
Rutgers University, Dept. of Geological Sciences, Piscataway, NJ

Rift basins and passive margins are key areas for hydrocarbon exploration and production. Some examples include the North Sea, Norwegian Sea, Brazil, and northwest shelf Australia. The Fundy rift basin of Maritime Canada, like many of the rift basins mentioned previously, has undergone two distinct periods of deformation: a synrift extensional and a postrift contractional phase (basin inversion). Previous work using seismic-reflection profiles and field mapping has determined that the geometry of postrift contractional structures is strongly influenced by synrift extensional structures. Consequently, it is problematic to use the orientations of these structures to constrain the shortening direction for the postrift deformation. The shortening direction will aid in the development of models for the origin of rift basin inversion, the importance of basin inversion to the rift-drift transition, and passive-margin evolution.

Small-scale structures that formed independent of preexisting zones of weakness may be used to unravel aspects of the extensional and compressional history from a variety of structural settings in the Fundy rift basin. These small-scale structures, produced during both phases of deformation, include faults with normal, reverse, strikeslip, and oblique-slip separation as well as deformation bands in porous sandstones. The orientations and kinematic characteristics of the small-scale faults can be used to evaluate extension and shortening directions related to the development of larger regional fault zones. Furthermore, small-scale structures in the inverted Fundy rift basin are analogous to other petroleum inverted rift basins.

AAPG Search and Discovery Article #90902©2001 AAPG Foundation Grants-in-Aid