It is the easternmost manifestation of Late Tertiary volcanic activity in the area (~200 km east of the present volcanic arc) and lies in the Sierras Pampeanas province, close to the southwestern margin of the Puna physiographic and tectonic province (Fig.  1 ).

Sediments at the base of the Cerro Durazno volcanics (the prominent escarpment in the background) are exposed as a result of uplift along a reverse NNW–SSE-trending fault (see Fig.  1 ).

The approximate location of the cross section A , B , C is shown in Fig.  1 .

Inclusions were analyzed in selected samples throughout the volcanic pile and in all the intrusions named in Fig.  1 .

This inclusion is also compared to the bulk analysis of an early lamprophyre dykes with SiO ₂ contents around 42 wt% emplaced into basement rocks east of the main volcanic complex (Capillitas Valley; Fig.  1 ).