1.57 Ga protolith age of the Neoproterozoic Forquilha eclogites, Borborema Province, NE-Brazil, constrained by U–Pb, Hf and Nd isotopes

•1.57 Ga protolith age of the metamafic rocks of the Forquilha eclogite.•These metamafic rocks were emplaced in an extensional setting.•The metamorphism that affected these rocks was related to the Brasiliano/Pan-African orogeny.

The 30 km-long, N–S-trending Forquilha eclogite zone, occurs within a Paleoproterozoic block mainly composed of gneisses and migmatites, in the Ceará Central domain, Borborema Province, NE Brazil. The Forquilha eclogite zone contains lenses of high to ultra-high pressure metamafic rocks, found as granulites and amphibolites associated with kyanite-sillimanite gneisses. Three samples of clinopyroxene-garnet amphibolite yielded the U–Pb zircon ages of 1566 ± 9 Ma, 1547 ± 37 Ma and 1532 ± 24 Ma, interpreted as the timing of igneous crystallization of the mafic protolith. Additionally, zircon grains of a leucocratic layer of a metamafic rock and a retrograded eclogite provided the less precise U–Pb ages of 1613 ± 40 Ma and 1454 ± 120 Ma, respectively. Lu–Hf and Sm–Nd model ages provided TDM (Hf) between 1.55 and 1.81 Ga with positive εHf values of +7.50 to +10.48, and TDM (Nd) ranging between 1.57 and 1.92 Ga with positive εNd values of +1.84 to +4.36. It is believed that part of the rocks of the Forquilha eclogite zone were emplaced as mafic dikes in an extensional setting at ca. 1.57 Ga.