In-situ trace element and Sr isotope signature of apatite: A new key to unravelling the genesis of polymetallic mineralisation in black shales of the Early Cambrian Niutitang Formation, Southern China

•This study focuses on apatite in the Niutitang formation.•Petrological and geochemical in-situ study helps deciphering its genesis.•A hydrothermal contribution is evidenced.•Element sources are better constrained.