The continental record of Ediacaran volcano-sedimentary successions in southern Brazil and their global implications

The Ediacaran is one of the most important periods on Earth evolution, including the first appearance of soft-bodied macrofossils, major climatic changes and a supposed rise in free oxygen. In southernmost Brazil, this period is represented by Camaqua Supergroup, including the Bom Jardim Group and the Acampamento Velho Formation, both of which record continental palaeoenvironmental changes in a more than 5000 m thick stratigraphic succession. Age constraints are given by seven Ar-Ar and U-Pb determinations on volcanic rocks, which bracket these units between c. 605 and 574 Ma, revealing the best dated and most continuous documented Ediacaran continental succession to date. Depositional systems evolution supports a Phanerozoic-type glacial context during the last Neoproterozoic glacial event and presents the Picada das Gracas Formation (580 +/- 3.6 Ma) as the first dated non-glacial unit coeval to the Gaskiers Formation.