Determination of mineralization age and ore-forming materials of the Dingjiashan Pb-Zn deposit in the Meixian ore concentration area, the central Fujian Province: evidence from the sphalerite Rb-Sr isotope

The Dingjiashan Pb -Zn deposit is located in the southwest of the Meixian ore concentration area in the central Fujian province. The Pb -Zn orebodies are predominantly hosted in the Meso-Neoproterozoic greenschist and marble of the Longbeixi Formation belonging to the Mamianshan Group in the layer, layer-like, and lenticular shape. In this contribution, the Rb-Sr dating for sphalerite was carried out in order to determine the mineralization age of the deposit. The isochron age of 8 sphalerite samples is 143.1 ±3.2 Ma (MSWD = 1.7), indicating that the deposit was formed in the Late Jurassic. The initial ⁸⁷Sr/⁸⁶Sr ratio of the sphalerite (0.71434 ±0.00036) and the previous S-Pb isotope studies indicate that the ore-forming materials at Dingjiashan may mainly source from deep-seated magma in the lower crust. Base on the above analyses, it is considered that the Dingjiashan deposit was formed under the condition of the extensional environment caused by the subduction of the ancient Pacific plate to the Eurasian continental plate, and was the product of contact metasomatism between the Late Jurassic to Early Cretaceous granite intrusions and the Meso -Neoproterozoic marble. The mineralization age of the Dingjiashan deposit has a constraint on that of the other Pb-Zn deposits from the Meixian ore concentration area.