Abstract The Campo Alegre Basin is a volcano-sedimentary sequence covering an area of about 500 km 2 , located at the northeast portion of Santa Catarina state (Brazil), and formed during the late stages of the Neoproterozoic era. Three main stratigraphic units compose this basin, the lowermost of which is the Bateias Formation, corresponding to the pre-volcanic stage. It is characterized by the fanglomeratic sediments at the basin’s northern boundary, which were deposited in a fluvial environment and progressively replaced by fluvial sandstones towards the south. Poorly sorted conglomerates and breccias compound the fanglomeratic facies, which comprises angular to subrounded fragments in a matrix ranging from sand fractions to fragments larger than gravel. The ubiquitous presence of volcanogenic and metamorphic fragments in the fanglomeratic facies strongly suggests that the Piên Magmatic Arc and a volcanic manifestation coeval with the earlier stages of the basin formation were important source areas, as well as the basin basement (the Luís Alves Terrane). In this sense, geological, petrographic, and detrital zircon geochronology data are combined in order to interpret the mechanisms that had acted during the deposition of these sedimentary rocks and to constraint the maximum depositional ages of Bateias Formation at ca. ~606 Ma.

ABSTRACT: The Limeira Intrusion is an occurrence related to the Mesozoic continental flood basalts of Paraná Magmatic Province, cropping out at the eastern São Paulo state. It is made up of basic-intermediate rocks with a great diversity of structures, textures and modal compositions, related to specific evolutionary process in a magma chamber. Previous geological and stratigraphic evidence suggests it has a lopolithic-like geometry rather than a conventional sill-like, assumed for most regional similar occurrences. 2D forward modeling of magnetometric data, based on available aerial and newly obtained ground data integrated with in situ rock magnetic susceptibility measurements, were used to test such hypothesis. The results, even considering intrinsic drawbacks of magnetometric theoretical models, are compatible with the geologic-based presumed intrusion geometry. The determination of intrusive bodies geometry is quite significant to explain their different emplacement mechanisms. In the case of Limeira Intrusion, the results suggest that the emplacement mechanism may occur, apparently, by inner-accretion of fresh magmatic pulses in its central region. Importantly, the magmatic evolution of lopolith-like basic-intermediate intrusions may open the way for extensive differentiation processes, with strong implications to petrology and metallogenesis.