Radiometric ages of some Cretaceous and Tertiary volcanic and intrusive rocks in South-central Arizona

Reconnaissance geologic mapping and radiometric ages provide the framework for correlation of Cretaceous and middle Tertiary volcanic and clastic rocks in the Vaca Hills and Eloy quadrangles, Arizona. The radiometric ages also record a middle Tertiary thermal event of much greater extent than .suggested by the volume of middle Tertiary igneous rocks present in outcrop.