Zircon U-Pb age and trace element data for igneous rocks in the Cortez area, Nevada

The Cortez region in north-central Nevada hosts the second largest concentration of Carlin-type gold deposits in Nevada. The origin of these deposits is debated, and major questions remain concerning the role of magmatism in their formation. To understand the Mesozoic and Cenozoic magmatic history of the Cortez region, twenty-one samples of igneous rocks ranging from Jurassic to Eocene were sampled, including drill core from around several of the major deposits. Individual zircon grains from these samples were analyzed by Sensitive High Resolution Ion Microprobe (SHRIMP) for uranium lead ages and a suite of trace elements. Most samples are Eocene, in particular the dikes associated with Cortez mineralization. Although no Cretaceous rocks igneous rock are exposed, Cretaceous xenocrysts were found in some samples indicating the presence of Cretaceous rocks at depth.