PALEOMAGNETIC EVIDENCE FOR COUNTERCLOCKWISE BLOCK ROTATION IN THE NORTH NEVADA RIFT REGION

Paleomagnetic data from mid-Miocene dikes and flows at three localities within the north Nevada rift indicate that some crustal blocks have rotated approximately 19° (±7°) counterclockwise relative to stable North America. As one possible consequence, a revised mid-Miocene extension direction for the area is about N89°E-S89°W, indicating an approximately 25° difference between mid-Miocene and modern least principal stress directions. The rotation may be accommodated by a right-lateral component of slip on northwest-trending oblique slip faults. These, as well as data from other parts of the Basin and Range province, indicate that strike-slip faulting and associated block rotation contributed to Cenozoic extension. © 1990 Geological Society of America.