Trishear 3D a kinematic model for oblique-slip and strike-slip structures.

CRISTALLINI, E.O.; GIAMBIAGI, L.; ALLMENDINGER, R.

GEOLOGICAL SOCIETY OF AMERICA BULLETIN

Geological Society of America

Año: 2004 vol. 116 p. 938 - 952

0016-7606

Most structural/kinematic models are inherently two-dimensional; even several recent three-dimensional models are “pseudo–three-dimensional” in that they consist of a series of parallel two-dimensional cross sections. Lack of a true three-dimensional formulation hampers our abilities to simulate three-dimensional structures such as oblique- and strike-slip faulting and displacement gradients perpendicular to the slip vector. The mathematical formulation of trishear deformation using incompressibility of fl ow is well suited to a solution in three dimensions. We derive one plausible velocity fi eld for true three-dimensional fl ow in a triangular shear zone. This formulation allows us to simulate the deformation in oblique-slip deformation zones as well as fl ower structures associated with strike-slip fault zones. The strain distribution in fl ower structures combined with some simple mechanical assumptions suggests that faults in these zones would have a helicoidal geometry. The results of the kinematic model compare well to well-described structures in the Colorado Plateau, Andaman Sea, and Death Valley, as well as to data from analogue experiments.