Early Miocene alluvial-lacustrine system in the Collón Cura basin and controls on the development of diatomite

Abstract

The sedimentological and compositional analyzes performed in this contribution allowed interpreting the depositional systems and the volcano-sedimentary supply of the early Miocene deposits of the Collón Cura Basin. These analyzes together with the incorporation of new sections, suggest a volcaniclastic alluvial system related to a lacustrine system with diatomites developed towards the centre of the basin. The development of these systems responds to the interaction of tectonic, magmatic and climatic processes that occurred in the Andean Patagonian retro arc, such as the initial compartmentalization of the foreland, the intermittent and distal pyroclastic supply associated with arc magmatism, and a temperate sub-humid climate linked to the middle Miocene Climatic Optimum and the incipient rain shadow effect. This context is conducive to the development of diatomites in the lacustrine system, with volcanic and climatic controls facilitating the contribution of silica necessary for their growth.