Geochronology And Isotope Geochemistry Of The Yingfang Pb-Zn-Ag Deposit: Implications For Large-Scale Metallogeny Along The Northern Flank Of The North China Craton

The northern flank of the North China Craton (NCC) hosts a linear zone of gold, molybdenum, silver, lead, and zinc polymetallic ore deposits. Among these, the Yingfang Pb-Zn-Ag deposit is located in the central part of the Yanshan-Liaoxi metallogenic belt (YLMB) which extends for approximately 1000 km and forms part of the major mineralized zone. In this study, we characterize the mineralization and trace the ore genesis based on new sulfur and lead isotopic geochemistry and evaluate the timing of mineralization from Rb-Sr isotope dating of sulfides. The pyrite delta S-34 values range from +3.2 parts per thousand to +5.8 parts per thousand with a mean at +4.07 parts per thousand, close to the values of mantle and meteorite sulfur. The Pb-206/Pb-204 values range from 16.833 to 18.956, Pb-207/Pb-204 from 15.374 to 15.522, and Pb-208/Pb-204 from 37.448 to 37.928. Five samples of sulfide, from the Yingfang deposit, yield a Rb-Sr isochron age of 135.7 +/- 4.1 Ma. This age is close to the age of the adjacent Niujuan Ag-Au deposit and the associated Er'daogou granite, suggesting a close relationship between magmatism and metallogeny in this region. The S and Pb isotopes of the regional silver polymetallic deposits show similar sources of ore-forming materials. According to a compilation of the available age data on the Mesozoic ore deposits in the northern flank of the NCC, we divide the mineralization into the following four periods: 240-205 Ma, 190-160 Ma, 155-135 Ma, and 135-100 Ma. Mesozoic magmatism and mineralization in the Yingfang deposit mainly took place at 245 Ma and 145-135 Ma. We correlate the Pb-Zn-Ag mineralization to metallogeny associated with large-scale inhomogeneous lithosphere thinning beneath the NCC.