Crustal contribution in the genesis of the bimodal Triassic volcanism from the Coastal Range, central Chile

摘要

Triassic volcanism in he Coastal Range of central Chile is represented by the Pichidangui Formation (31° 54' to 32° 15'S ) composed of acid and basic lava flows and sub - volcanic intrusives with some sedimentary intercalations. Both rock types have been affected by non - deformational very low - to low - grade metamorphism. Their geochemical characteristics indicate a tholeiitic affinity, with Nb/Y ratios ranging from 0.20-0.17. Low [mg] values in the basic rocks are indicative of non - primitive liquids.