Calcic skarns and transversal zoning in the Banat mountains, Romania: indicators of an Andean-type setting

Abstract

Calcic skarn deposits related to Upper Cretaceous – Paleocene banatitic intrusions are widely developed in the Banat Mountains (southwestern Romanian Carpathians). There is a spatial distribution of banatitic igneous rocks and associated ore deposits in parallel zones, due to subduction beneath the southwest Carpathians. As a result three distinct petro-metallogenetic units developed, i.e. marginal unit: Moldova Nouă– Sasca; median unit: Ciclova – Oravita; and the inner unit: Dognecea – Ocna de Fier. The magmatism changed inland from monzonite and diorite → granodiorite occurrences to granodiorite → granite plutons. The related mineralization shifted simultaneously from Cu (Mo) to Cu-Mo (W) and eventually Fe(Cu)/Pb-Zn. The distribution of both magmatism and related ore deposits in parallel petro-metallogenetic zones is considered similar to that in the Andes. In particular, calcic skarns and related ore deposits that occur in these units show a transversal zonal variation represented by compositional features of pyroxene and granat, sequence of mineralization and metallogenetic environment. Such zonal characteristics represent an additional but nonetheless significant indicator for an Andean-type subduction-related setting.