Bean Canyon Formation
Bean Canyon Formation
Paleozoic
Marble, quartzite, pelitic schist, silicic metatuff, and calc-silicate hornfels overlying metabasalt and ultramafic rocks. The amphibolite metabasalt has yielded a latest Cambrian zircon U-Pb age of ~487 Ma, and a dacite metatuff from the overlying section has a Permian zircon U-Pb age of ~273 Ma (Chapman and others, 2012). Trace element analysis of metatuff from the top of the section suggests a volcanic arc origin (Chapman and others, 2012). The formally accepted age of this unit is Jurassic, but that is based on a Rb-Sr age of ~150 Ma (Ross, 1989) without a reported location. We suggest the age-dated sample is from the Tylerhorse Canyon area that has yielded Jurassic fossils which we have designated Tylerhorse Canyon schist. We retain the larger portion of the previously mapped extent of the unit which has yielded Paleozoic U-Pb ages.