Age and Tectonic Significance of Volcanic Rocks, Death Valley Area, California
Potassium-argon dating of volcanic rocks referred to the Artist Drive Formation or “Older Volcanics” in the Death Valley region, yields ages between 6 and 9 m.y. Determinations on both younger and older units substantiate these values and compress the tentative chronology of the region outlined by previous authors. Upper and lower age limits are established for the Furnace Creek Formation, requiring a minimum depositional rate of 127 cm/1000 yr at the north end of the Black Mountains. A denudation rate in excess of 50 cm/1000 yr is suggested for at least part of the Death Valley area during the late Pliocene. Two temporally and structurally distinct episodes of deformation are postulated, which may be responsible for the diverse structural features referred to the Amargosa chaos or thrust complex. Tectonic implications include the synchroneity of normal faulting, strike-slip faulting, folding, and formation of at least part of the Amargosa chaos in the last 6 m.y.