Geochronology and Lu-Hf isotope of Early Paleozoic Zhuya-Shiban gabbros in Yunkai terrane, South China

Early Paleozoic mafic intrusive rocks in Yunkai terrane commonly occur as small stocks that intruded into pre-Cambrian strata and/or contemporary gneissic granite, with main rock types being gabbro and norite gabbro.The gabbros in Zhuya and Yunlu yielded ²⁰⁶Pb/²³⁸U weighted age of ca.445Ma.The gabbros show relatively high MgO, CaO, low TiO₂ content, very low ∑REE (20.8×10^-6~26.6×10^-6), weak enrichment of LREE and strong depletion of HFSE (Nb-Zr-Ti-P).Zircons give negative ε_Hf(t) and T_DM model ages from 1.1Ga to 1.4Ga, showing the features of an enriched mantle source.Tectonic setting analysis shows that the gab-bors acted like volcanic arc rocks.Previous studies show many Early Paleozoic mafic rocks in Cathaysia Block with characteristic fin-gerprints of arc volcanic rock features, and hence the Early Paleozoic geotectonic evolution history in Yunkai terrane (even Cathaysia Block) should be reconsidered.