Sierra de Papachacra basement mafic magmatism, Pampean Ranges of Catamarca: geologic and geochemistry aspects

Abstract

A lithostratigraphic sequence for the metamorphic and granitoid basement in the area of ??the Sierra de Papachacra is proposed on the basis of geological, petrografical and geochemical studies of the basic rocks outcropping in the area.

The sequence begins with synsedimentary magmatic activity, followed by La Cuesta Ortoanfibolite and dikes in the metamorphites (G1 and G2 types). Then G3 and G4 dikes are placed in Chango Real Formation, but the chronology of them is unknown. Finally, hypabissal dykes G5 (DBE) era located in the Papachacra Granite.All rock types have low Sr contents and high content of the Th-U pair, with respect to the mean basalts. G1 and G2 types have high LIL and low Ta and Nb. The gabbro dike (G3) is grouped with type G5 by the trace elements but with high content in SiO2. The G4 type has low Nb values, with Ta above the mean and irregular LIL contents. Geochemistry indicates tectonic setting of magmatic arc and a later distensive stage.