geologia e recursos naturais

Our study helps to unravel the complexity of the Lomagundi–Jatuli event, the largest and longest positive carbon isotope excursion ever recorded on the Earth’s surface, by providing a unique view of Paleoproterozoic graphitic rocks from the Borborema province of Northeastern Brazil. Through detailed mineralogical, textural, chemical and isotopic analyses, we bring a new perspective that provide support to elevated primary productivity and large-scale organic carbon burial during the Lomagundi–Jatuli event.

ABSTRACT

Abstract

This study presents a hydrogeological characterization that fills knowledge gaps in an area where a complex geological scenario connects two fractured (granite/metamorphic rocks and diabase) and one porous (sedimentary rocks) aquifer systems. Previous groundwater studies from the four local deep supply wells suggested the sedimentary aquifer as the source of uranium (∼60 μg/L) in one of the wells. Despite the water extraction interruption from this well, this finding needed to be supported by evidence provided by the geological and structural characteristics of the aquifers.

The Brejuí W-Mo skarn deposit is the main scheelite deposit of the Seridó tungsten province (Borborema province, NE Brazil). It constitutes the largest Brazilian W ore reserve. The orebodies are hosted in the metasedimentary Jucurutu Formation of the Seridó Group (650–610 Ma), close to the margin of the Neoproterozoic Acari pluton (Brasiliano orogeny). Skarns include prograde and retrograde mineral assemblages. Infrared spectral analysis shows that the skarns mainly reflect retrograde mineral assemblages, formed in three different hydrothermal alteration stages with overprinting.