Paleoecologia do Folhelho Lontras, Formação Campo Mourão, Cisuraliano, Brasil

Abstract

The Lontras Member (Cisuralian) comprises the upper portion and the maximum transgressive moment of the Campo Mourão Formation. It is partial represented by the fossiliferous black shale namely Lontras Shale at Campáleo outcrop in Mafra, Santa Catarina. This site has been notorious to the national and international scientific community in the last few decades due the excellent fossil preservation of diverse taxa, which insert the Lontras Shale along few others Carboniferous-Permian shales with good preservation, as for example the Mecca Quarry Shale, Linton Formation, United States of America. However, despite many taxonomical studies, this shale lacks data regarding paleoecology and paleoenvironment which favors new scientific projects. Thus, this doctor thesis is applied to detail the geochemical, taphonomy and paleontological content of the Lontras Shale at Campáleo outcrop, in order to characterize not only the fossil assembly, but also the paleoecology and the paleoenvironment. Considering the integrated organic geochemical data (TOC, TS, biomarkers, and palinofacies) and the inorganic geochemical data (U/Th ratios, authigenic uranium, molybdenum and framboid pyrite size) the Lontras Shale were deposited in a restricted marine environment (assigned with two system tract: Trangessive and High Sea). With predominance of anoxic/euxinic bottom-water conditions. Theses conditions was caused by elevated productivity in the basin, which was related to deglaciation, marine transgression, the increased delivery of terrestrial nutrientes and also by advection of denitrified water mass from the Panthalassic Ocean. The prolonged periods of sea-floor anoxia/euxinia enhancing the preservation of the fossil from this Paleozoic Largestätten. Taphonomical signatures from seven phyla have been identified, allowing us to separe them into autochthonous, parautochthonous and allochthonous