Dados da Submissão

Título

AN INTEGRATED ZIRCON GEOCHRONOLOGY INVESTIGATION OF UHT GRANULITES FROM THE CAPARAÓ COMPLEX, ARAÇUAÍ OROGEN

Texto do resumo

Metamorphic rocks formed at extreme conditions under ultra-high temperature (UHT) are important records of processes acting in the lower continental crust during orogenesis. The in-situ dating techniques (i.e., LA-ICP-MS and SHRIMP/SIMS) have been widely applied in petrochronological investigations to constrain the timing of metamorphic processes. However, the large uncertainties (~1-2%) of the in-situ methods do not allow a precise and reliable definition of the P-T-t paths in Neoproterozoic samples hampering a comparison with more recent orogenic processes. The CA-ID-TIMS (chemical abrasion-isotope dilution-thermal ionization mass spectrometry) method allows geological processes to be assessed at a very high temporal resolution (0.01-0.05%), allowing a precise determination of metamorphic timescales in ancient orogenic belts. In this study, an integrated zircon U-Pb geochronology approach using both in-situ (LA-ICP-MS) and high-precision (CA-ID-TIMS) dating techniques combined with zircon trace element analyses, trace element thermometry and phase equilibrium modeling will be applied in UHT granulites from the Serra do Caparaó Complex (Araçuaí Orogen, SE Brazil) to establish more robust pressure-temperature-time (P-T-t) paths and obtain more reliable timescales of the metamorphic processes active in the Neoproterozoic lower continental crust.

Palavras Chave

U-Pb zircon; LA-ICP-MS; high-precision geochronology; UHT granulites; Araçuaí orogen