The Early Ordovician in the Famatina Range

Bodenbender (1911) reported the occurrence of Early Ordovician rocks in the Famatina Range for the first time. He described graptolitic black shales at Pena Negra, and limestones and schists containing trilobites and brachiopods at Rio Volcancito (Bodenbender, 1911, 1916). These outcrops were formally assigned to the Lower Tremadoc Volcancito Formation by Harrington (in Harrington and Leanza, 1957). Subsequently, Alderete (1968) described additional fossiliferous sediments at the Portezuelo de La Alumbrera Creek, in the southern part of the Famatina Range. Recent stratigraphic and paleontologic analyses have demonstrated that the Pena Negra/Rio Volcancito outcrops clearly differ from those of the southern Famatina Range. The marls, sandstones and black shales from the type locality belong to the Volcancito Formation, whereas the fine grained sandstones, siltstones and mudstones from the Portezuelo de La Alumbrera Creek are referred to as Bordo Atravesado Formation.