CONSTRAINING THE AGE OF NEOPROTEROZOIC GLACIATION IN EASTERN BRAZIL: FIRST U-Pb (SHRIMP) DATA OF DETRITAL ZIRCONS

Abstract

Detrital zircons extracted from a diamictite-bearing formation of the Macaúbas Group, located within the Aracuai Belt (Eastern Brazil), were dated using a Sensitive High-Resolution Ion Microprobe (SHRIMP). The youngest reliable measurement sets the upper limit for the age of the glaciation at 950 Ma. The main group of zircons (1000-950 Ma) is a good evidence of a magmatic episode, interpreted as related to the rift stage of the Araçuai-West-Congo basin system.