Magmatic source, petrogenesis, and tectonic setting of the Concepción del Oro Igneous Complex: a geochemical and isotopic (Rb–Sr and Sm–Nd) study of a late complex of the Cretaceous–Eocene Mexican Magmatic Arc

Abstract During the Mexican fold-and-thrust belt tectonics, inboard migration of long-term cordilleran magmatism typifies geological setting during Cretaceous–Paleogene period. The Concepción del Oro Igneous Complex (COIC) represents one most internal and isolated magmatic pulses that occurred this activity. In work, plutonic rocks from COIC were studied using petrography, U–Pb geochronology, whole rock zircon geochemistry, Rb–Sr Sm–Nd isotopes. Petrographic observations reveal mainly fine-to-coarse-grained granodioritic composition for masses. analyzes four samples largest center yielded ages ranging 42.6 ± 0.2 Ma to 41.8 0.1 Ma. granodiorites exhibit geochemical features typical I-type, high-K calc-alkaline, Magnesian rocks. chondrite-normalized REE diagram summarizes enrichment LREE ([La/Yb] N = 5.94–19.19) moderate slightly negative Eu anomalies (Eu/Eu* 0.63–0.94). addition, mantle-normalized spider shows LILE, such as Rb Ba, depletion HFSE, Nb, Ta, Ti, P. Whole-rock geochemistry indicate a post-collisional with an inherited arc fingerprint. Ti-in-zircon temperatures saturation thermometry suggest origin evolved relatively cold melts (~ 700 °C). Moreover, systematic variations in ratios highly incompatible elements, La/Sm (6.54–3.79) Rb/Sr (0.32–0.10), narrow ranges Zr/Hf (36.25–48.84) 147 Sm/ 144 Nd (0.0941–0.1261), fractional crystallization main petrogenetic process involved formation isotopic data magma source mixing juvenile material older continental crust, indicated by 87 Sr/ 86 Sr ( t 40) between 0.704583 0.707783, 143 Nd/ varying 0.512478–0.512702 (εNd + 2.18 − 2.10), TDM (Nd) 1.03 0.62 Ga. We conclude parental was derived partial melting lower crust triggered emplacement underplated at base end orogenic cycle.