Geochemistry of the Northern Paraná Continental Flood Basalt (PCFB) Province: implications for regional chemostratigraphy

ABSTRACT:

The Paraná Continental Flood Basalt (PCFB) province is one of the largest igneous provinces on Earth, but little is known about the architecture and geochemical characteristics of the lava flows. In this context, a set of borehole samples arranged in an NEE-SWW profile - more than 600 km long - located in the northern PCFB was used to define its chemostratigraphy. In this region, the outcrops are rare, and the volcanic piles are covered by hundreds of meters of sedimentary rocks from the Bauru Sub-Basin. This study aimed to explore the chemostratigraphic column from northern PCFB to improve the understanding of its internal architecture and to characterize the flood basalt sequences by using the petrography and elemental geochemistry of surface and borehole samples. The results showed the presence of the main four magma types, which were essentially distinguished by their P₂ O₅ , TiO₂ and Sr concentrations, as well as Zr/Y ratios, with excellent chemostratigraphy relations.

KEYWORDS:
Paraná Continental Flood Basalts; chemostratigraphy; volcanic successions; magma types; geochemistry of boreholes