Geochronology of the Cordillera Real granitoids, the inner magmatic arc of Bolivia

The Cordillera Real granitoids are a suite of Triassic and Oligocene plutons in the core Eastern Central Andes Bolivia. Their tectonic setting, chemical ore compositions make them part so-called “Inner Magmatic Arc”, which differs from current “Magmatic Arc” located immediately to west. U-Pb SHRIMP data were obtained order constrain crystallization ages. group yielded following results: 239±2 Ma for Huato granite, 231±1 Illampu granodiorite, 221±3 Huayna Potosí granite 223±2 Taquesi granodiorite. For we ages 27 two samples Quimsa Cruz granite. Secondary processes related regional thermal anomalies magmatic melt-enrichment, reset K-Ar isotopic systems, producing: a) younger by Ar loss b) anomalous plot Concordia diagram reorganization ratios. As noted previous studies, most zircon analysed Zongo/Kuticucho exhibited extremely high U enrichment, producing reverse discordia curves that obscure true age. Relatively abundant inheritance was found these “cold” granitoids, with suggesting provenance early Paleozoic metapelites also contained recycled older sources. This relatively xenocrystic probably records influence subduction process acting during Gondwanide orogeny (336-205 Ma) as an overall arc environment, punctuated at its final stage imprint continental rifting (245-220 Ma).