Age and geochemistry of Cambaí Complex, São Gabriel Terrane, Brazil: Arc-related TTG-like rocks

Abstract

The Cambaí Complex TTG-like rock assemblage representing a Neoproterozoic juvenile magmatic arc is part of the São Gabriel Terrane that crops out in the SW domain of the Dom Feliciano Belt in S-Brazil. Geochemistry of dioritic, tonalitic, trondhjemitic, and granodioritic rocks of this complex indicate their low-medium-K calc-alkaline geochemical affinity being metaluminous and with fractional crystallization as the main magmatic process of formation. Whole-rock geochemistry enrichment in LILE as Sr and Ba in relations to HFSE as Y and Zr, with flat patterns in an REE spider diagram, with enrichment to chondrite ((La/Yb) N = 1.3 to 17.2) and low Eu anomaly (Eu/Eu* = 1.2), with 87Sr/86Sr(i) from 0.704260 to 0.706430, 143Nd/144Nd(t) from 0.512070 to 0.512080, Nd-TDM model age from 820 to 852 Ma, εNd(t) from 3.9 to 4.2 and 207Pb/204Pb and 206Pb/204Pb ranged from 15.5040 to 15.5776 and 17.5313 to 18.5696, suggest an immature magmatic arc-related rock setting. Geochronology U–Pb LA-ICP-MS in zircons from diorites shown Tonian crystallization ages (745 ± 4 Ma, 748 ± 5 Ma, 752 ± 4 Ma). Any model proposed to explain the history of the evolution of the West Gondwana Supercontinent needs to consider the accretion of juvenile crust from primitive mantle source with minor crustal contamination in this segment of the orogenic collage during the Neoproterozoic.