Pleistocene volcanism along the margins of the Canal de Ballenas transform fault, Gulf of California

Pleistocene subaerial volcanism along the margins of the Ballenas Channel, northern Gulf of California, is represented by two morphologically young dacite dome complexes exposed at the opposite edges of sheared continental crust: Isla Coronado in coastal Baja California, and the Lobera volcanic complex in west-central Isla angel de la Guarda. Single crystal zircon U-Pb crystallization ages of Coronado and Lobera volcanoes range between ca. 250 and 1000 ka, indicating maximum ages for the eruptions. Eruption ages are directly constrained by an 40Ar/39Ar whole-rock age of 692 +/- 164 ka for one of the lava units in the Lobera volcanic complex. Trace elements in Pleistocene zircon indicate continental affinity, which supports radiogenic (Nd, Sr) isotopic data that were modeled using different mixing and AFC scenarios indicating a MORB-type primary magma with significant (similar to 10-20 %) crustal assimilation involving tonalitic basement of the eastern Peninsular Ranges Batholith.

Automated summary

Pleistocene subaerial volcanism in the northern Gulf of California is represented by two young dacite dome complexes, Isla Coronado and Lobera volcanic complex. The eruption ages of these volcanoes were determined using single crystal zircon U-Pb crystallization ages, and they are estimated to be between 250 and 1000 thousand years ago. The trace elements in the Pleistocene zircon indicate a continental affinity, suggesting crustal assimilation involving tonalitic basement.