矿床地球化学国家重点实验室知识库

The Habo alkaline intrusion, which is located in the south of the Sanjiang area, Yunnan Province, China, is a typical Cenozoic alkaline intrusion. There are a series of small to medium-sized Au and Pb–(Zn) deposits around this intrusion. Those deposits are spatially associated with the Habo alkaline intrusion. (1) The δ³⁴S values of sulfides from Au deposits range from −1.91 ‰ to 2.69 ‰, which are similar to those of Pb–(Zn) deposits (−3.82 ‰ to −0.05 ‰) and both indicate a much greater contribution from magma. (2) The Habo alkaline intrusion has relatively homogeneous Pb isotopic compositions with ²⁰⁶Pb/²⁰⁴Pb ranging from 18.608 to 18.761, ²⁰⁷Pb/²⁰⁴Pb from 15.572 to 15.722 and ²⁰⁸Pb/²⁰⁴Pb from 38.599 to 39.110. These Pb isotope ratios are similar to those of Au deposits, whose ²⁰⁶Pb/²⁰⁴Pb range from 18.564 to 18.734, ²⁰⁷Pb/²⁰⁴Pb from 15.582 to 15.738 and ²⁰⁸Pb/²⁰⁴Pb from 38.592 to 39.319. Pb ratios in both the intrusion and Au deposits suggest that Pb mainly derived from the depth, probably represents a mixture of mantle and crust. Pb–(Zn) deposits, however, show a decentralized trait, and most of them are similar to that of the alkaline intrusion with ²⁰⁶Pb/²⁰⁴Pb ranging from 18.523 to 18.648, ²⁰⁷Pb/²⁰⁴Pb from 15.599 to 15.802, and ²⁰⁸Pb/²⁰⁴Pb from 38.659 to 39.206. (3) In the plumbotectonic diagram ²⁰⁷Pb/²⁰⁴Pb versus ²⁰⁶Pb/²⁰⁴Pb, almost all of Au and Pb–(Zn) deposits have the same projection area with the Habo alkaline intrusion, which indicates that those deposits almost share the same source with the alkaline intrusion. (4) Isotopic age of the Habo alkaline intrusion is 36–33 Ma, which is similar to that of Beiya, whose ore-related alkaline porphyries age is 38–31 Ma and molybdenite Re–Os age is 36.9 Ma. Therefore, along with S–Pb isotope traits, we suggest that the Habo Au and Pb–(Zn) deposits should be typically Ailaoshan-Red RiverCenozoicalkaline-related deposits and ore-forming ages of these deposits should be later than that of the Habo alkaline intrusion.