Miocene crustal extension and uplift in southeastern Nevada: constraints from fission track analysis

The Gold Butte block of southeastern Nevada appears to be a cross section through the upper ~17km of Colorado Plateau crust, tilted eastward and tectonically denuded via top-to-the-west normal faulting in Tertiary time. Apatite fission track dating and confined track-length distribution have been used to determine the time of unroofing of the Gold Butte block and hence the timing of one episode of extension in this part of the Basin and Range province. Samples collected in an east-west transect along the block indicate an abrupt transition from a period of relative thermal and tectonic stability to the onset of rapid cooling. The fission-track data indicate that the unroofing of the Gold Butte block was rapid and that the crustal section was brought to within a few kilometres of the surface at c15 Ma. -from Authors