The volcanic rocks of the Lower Cretaceous Paraná-Etendeka Igneous Province, in Brazil, are grouped in the Serra Geral Group. The province can be chemically divided into low-TiO2, and high-TiO2. In southern Brazil, the low- TiO2 lava pile reaches a thickness of ~1 km and is formed of heterogeneous lava packages here divided into four lava formations. Torres Formation (TF) is characterized by chemically more primitive basaltic (N5 wt% MgO) compound pahoehoe flow fields; these lavas stratigraphically overly aeolian sandstones of Botucatu Formation and represent the onset of the volcanic activity. Vale do Sol Formation (VSF) groups vertically stacked sheet-like rubbly pahoehoe basaltic andesites (SiO2 N 51wt%; MgO b 5 wt%). These lavas covered the former basalts in the Torres Syncline axis and pinch out towards southwest and represent the most voluminous mafic lava flows. Dacites and rhyolites of Palmas Formation (PF) overlay VSF flows in the central and eastern outcrop area and rest directly upon TF lavas in thewest. The acidic units were emplaced as lava domes andwidespread tabular lava flows. Esmeralda Formation (EF) is the upper stratigraphic unit and it is formed by a basaltic pahoehoe flow field emplaced during the waning phase of volcanic activity of the low-TiO2 lava sequence. Sedimentary interbeds are preserved throughout thewhole lava pile andwere deposited during quiescence periods of volcanic activity, and represent important stratigraphic markers (e.g. TF-VSF contact). The newly proposed stratigraphy provides promptly recognized stratigraphic units in a regional framework of fundamental importance for future correlations and provide vital information in the understanding of how the Paraná-Etendeka Igneous Province evolved through time.
The research is part of Lucas Ph.D. thesis and was carried out with the financial support of CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico -Brazil) and BG-Brazil/Shell. The University of Aberdeen and the Federal University of Rio Grande do Sul are acknowledged for additional support. Evandro is thankful for research grants from CNPq (project - 479784/2012-4), FAPERGS (100713) and FAPESP (2012/06082-6). M. Rossetti and F. Luz are acknowledged for their support during fieldwork and samples collection. We acknowledge Dougal Jerram and Pablo D. Harris for their constructive reviews and Edgardo Cañón-Tapia for editorship.
- Paraná-Etendeka Igneous Province
- Stratigraphy of LIP
- Lava emplacement