Defining the Ediacaran-Cambrian passage in the SW of the Gondwana Supercontinent: high-resolution geochemistry analysis of the Tagatiya Guazu Formation, Itapucumi Group, PY

• Grant number: 20/00483-5
• Support type: Scholarships in Brazil - Master
• Effective date (Start): August 01, 2020
• Effective date (End): April 30, 2022
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal researcher: Lucas Verissimo Warren
• Grantee: Gabriel Correa Antunes
• Home Institution: Instituto de Geociências e Ciências Exatas (IGCE). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil

Abstract

The transition from the end of the Ediacaran period to the Cambrian is characterized by profound changes in terrestrial ecosystems, whether due to bioevolutionary, climatic or geochemical issues, such as changes in the configuration of the marine substrate and in the chemistry of the oceans, as well as by the emergence of the first animals with complex habits and apparent replacement of late Ediacaran's characteristic fauna. The temporal and stratigraphic definition of the passage of these eons, plus the definition of the environmental conditions then in force and their role as evolutionary forces, constitute one of the great current scientific challenges of geology. In this context, the Tagatiya Guazu Formation (Itapucumi Group, northern Paraguay) is inserted, a non-deformed and non-metamorphized carbonate unit with an important paleontological content. This is characterized by different types of skeletal organisms - such as Cloudina, Corumbella and Namacalathus - attributed to the Nama Assemblage, of terminal Ediacaran age. Recently, geochronological and paleontological data revealed that the Ediacaran-Cambrian passage is possibly found in the top fossiliferous strata of this unit. Considering the importance of the Tagatiya Guazu Formation fossil assemblage and the growing consolidation of multi-proxy approaches, a high-resolution geochemical and chemostratigraphic analysis of the fossiliferous interval of this unit is proposed in this master's project. For this purpose, traditional stratigraphy methods will be used together with C and O isotope data, large elements, traces and TOC of specific intervals. The application of different methodologies will be fundamental in the stratigraphic refinement and in the definition of the interval that corresponds to the Ediacaran-Cambrian passage in the Itapucumi Group. In addition to the clear stratigraphic implications, this project is expected to contribute to the biostratigraphic detailing of this unit, as well as to clarify its correlation with other coeval units around the world and help to define the causes, effects and influences of geochemical variations in the emergence of the first animals with complex habits on Earth. (AU)