Chaicayán Group

Chaicayán Group is a group of poorly defined sedimentary rock strata found in Taitao Peninsula in the west coast of Patagonia. The most common rock types are siltstone and sandstone. Conglomerate occur but is less common.

Study of fossils and uranium–lead dating of detrital zircons indicate a Miocene age, at least for the upper sequences. The Chaicayán Group deposited likely as a result of a marine transgression that drowned much of Patagonia and Central Chile in the Late Oligocene and Miocene.

The group is intruded by porphyritic stocks and sills of Pliocene age.