Análises de isótopos estáveis de carbono e oxigênio em carapaças de ostracodes: estudos metodológicos e aplicações no cretáceo do Brasil

Abstract

Ostracods are used in the study of stable isotopes due to the high environmental sensitivity of their carapaces, wich are rapidly calcified preserving the isotopic characteristics of water in different aquatic environments in wich they lived. Cretaceous ostracods have potential for carbon and oxygen stable isotopic studies as well as recent and Cenozoic ones, commonly used. The carbon isotopes provide information about biological paleoproductivity and nutrients availability in oceans and lakes, while oxygen isotopes estimate paleotemperature and paleosalinidaty that prevailed in both marine and non-marine deposits. Besides the palaeoenvironmental information, the isotopic data allow the dating of geological events. The scarcity of isotopic studies on Cretaceous ostracods carapaces led to the development of experimental and comparative studies as subject of this doctoral thesis. This thesis presents the methodologies used in the rock disaggregation and preparation and selection of ostracods carapaces for isotopic analysis. The good results obtained in isotopic analysis of marine and non-marine ostracods carapaces demonstrated that they can be used in paleoenvironmental studies, provided they appropriate techniques applied.