Paleomagnetism of the Late Permian-Early Triassic Koipato Volcanics, Nevada: implications for latitudinal displacement

Abstract

We have obtained paleomagnetic directions for 11 basalt flows of the probable Early Triassic Koipato Volcanics from the South Tobin Range of western Nevada. The mean direction for these flows (D = 350.3°; I = 39.0°; α95 = 8.0°) is discordant with respect to the APW path for North America. A positive fold test, a consistency-of-reversal test, the shape and amount of between-site dispersion, and other considerations strongly suggest that the magnetization is pre-folding and probably primary. The most likely explanation for this discordance is southward transport and clockwise rotation of the sampling area. The most probable amount of displacement and net rotation are 1400 km and 25°, respectively. These observations have considerable significance for the early Mesozoic tectonics of the Great Basin. © 1989.