Magmatic evolution of the La Huerta Plutonic Complex, Jalisco: A 80–70 Ma record of arc magmatism along the Mexican Cordillera

Abstract

The La Huerta Plutonic Complex (LHPC) forms part of the Cretaceous Mexican Cordillera, located between the well-documented ~80 Ma Puerto Vallarta Batholith (PVB) and the ~65 Ma Manzanillo Plutonic Complex (MPC). The LHPC shares lithological and geochemical features with the aforementioned batholiths and is dominated by voluminous granitoids and hybrid intrusions ranging from gabbro to granitic compositions. Scarce cummulitic gabbroic plutons are also present. Detailed petrographic, geochemical, microchemical, and geochronological results provide evidence for three magmatic stages: (1) a gabbroic magmatism at >84 Ma (observed from field relations), (2) ~83–80 Ma granitic magmatism (U-Pb in zircon), and (3) a ~75–70 Ma gabbroic and granitic magmatism (U-Pb in zircon). Thermobarometric determinations (3.0–2.0 kbar and <900 °C) and Sr-Nd isotopic signatures in all lithologies (εNd_i from +4.2 to +6.2 and ⁸⁷Sr/⁸⁶Sr_i around 0.7035) suggest a shallow magmatic environment with low and heterogeneous crustal assimilation. These features hold considerable differences with the northern PVB and are more comparable to the MPC. The LHPC is interpreted as the south easternmost part of the PVB and as a transitional zone between the PVB and the MPC.