Proterozoic rocks of the Caballo Mountains and Kingston mining district: U-Pb geochronology and correlations within the Mazatal province of southern New Mexico
— Jeffrey M. Amato and Trey Becker

Basement rocks of the Caballo Mountains and Kingston mining district of south-central New Mexico are Proterozoic in age based on their exposure beneath a nonconformity with overlying Cambro-Ordovician Bliss sandstone. We used SHRIMP (sensitive high-resolution ion microprobe dating) to obtain U-Pb dates on zircon from four samples of igneous or metaigneous basement. A sample of foliated gneissic biotite granite from the Caballo Mountains yielded a date of 1681 ± 12 Ma (all uncertainties are at 2σ). Two undeformed samples from the Caballo Mountains include the Longbottom pluton, dated at 1486 ± 16 Ma, and the Caballo granite with an age of 1487 ± 24 Ma. A granophyre from the Kingston district yielded a date of 1654 ± 15 Ma. The two samples older than 1650 Ma are similar in age to other Mazatzal province basement that forms the country rock for the >1.4 Ga granites that are widespread throughout New Mexico. The samples from the Caballo Mountains are among the oldest granites that are part of the continent-wide ~1.4 Ga granite-rhyolite province. These data demonstrate the similarity of lithology and age of the Proterozoic basement of the Caballo Mountains and Kingston Mining District to other exposures of Proterozoic rocks in southern New Mexico such as the Burro Mountains of southwest New Mexico.