Jurassic to Tertiary tectonic, volcanic, and sedimentary evolution of the Southern Andean intra-arc zone, Chile (38-39°S):: A survey

In the Southern Andean arc, from Jurassic to Pliocene times, repeated periods of compressional and extensional tectonics coupled with subduction-related volcanism give the opportunity to study the relationship between tectonism, magmatism, and sedimentation across a composite section between 38 degrees and 39 degrees S. Marine Jurassic formations are associated with calc-alkaline and subordinately alkaline volcanic rocks. The Miocene lacustrine sedimentation was accompanied and mainly ruled by calc-alkaline volcanic activity, which is documented by changes of the detrital composition. The more differentiated volcanism (tholeiitic, calc-alkaline, alkaline) during the Pliocene is related to transtensional tectonics. The stable calc-alkaline component of the Jurassic to Pliocene volcanism confirms a long-term stationary arc segment. This history further suggests that a continuous evolution was modified by multiple source magmatic episodes associated with widening and narrowing in the arc.