Distal Pb-Zn-Ag veins associated with the world-class Donggou porphyry Mo deposit, southern North China craton

Publication date: April 2017
Source:Ore Geology Reviews, Volume 82
Author(s): Zhan-Ke Li, Shi-Jian Bi, Jian-Wei Li, Wen Zhang, David R. Cooke, David Selby
The southern North China craton hosts numerous world-class porphyry Mo and Pb-Zn-Ag vein deposits. Whether or not the Pb-Zn-Ag veins are genetically associated with the porphyry Mo system remains contentious. Here we focus on the genetic relationships between the Sanyuangou Pb-Zn-Ag vein deposit and the world-class Donggou porphyry Mo deposit, and discuss the potential implications from the spatial and temporal relationships between porphyry and vein systems in the southern North China craton.At Sanyuangou, vein-hosted sulfide mineralization mainly comprises pyrite, sphalerite, and galena, with minor chalcopyrite, pyrrhotite, bornite, tetrahedrite, covellite, polybasite and argentite. The mineralization is hosted by a quartz diorite stock, which has a zircon U-Pb age of 1756±9Ma. However, sericite from alteration selvages of Pb-Zn-Ag sulfide mineralization yields a well-defined ⁴⁰Ar/³⁹Ar plateau age of 115.9±0.9Ma. Although nominally younger, the sericite ⁴⁰Ar/³⁹Ar age is similar to the age of the nearby Donggou porphyry Mo deposit (zircon U-Pb age of 117.8±0.9; molybdenite Re-Os ages of 117.5±0.8Ma and 116.4±0.6Ma). Pyrite from Donggou has elevated contents of Mo and Bi, whereas pyrite from Sanyuangou is enriched in Cu, Zn, Pb, Ag, Au, and As. This trace element pattern is consistent with metal zonation typically observed in porphyry related metallogenic systems. Pyrite grains from Sanyuangou have lead isotopes overlapping those from Donggou (17.273–17.495 vs. 17.328–17.517 for ²⁰⁶Pb/²⁰⁴Pb, 15.431–15.566 vs. 15.408–15.551 for ²⁰⁷Pb/²⁰⁴Pb, and 37.991–38.337 vs. 38.080–38.436 for ²⁰⁸Pb/²⁰⁴Pb). Collectively, the geological, geochronological, and geochemical data support a magmatic-hydrothermal origin for the Sanyuangou Pb-Zn-Ag deposit and confirm that the Pb-Zn-Ag veins and the Donggou Mo deposit form a porphyry-related magmatic-hydrothermal system.Given the widespread Pb-Zn-Ag veins and Mo mineralized porphyries in many districts of the southern North China craton, the model derived from this study has broad implications for further exploration of Mo and Pb-Zn-Ag resources in the area.

Graphical abstract

http://ift.tt/2hKvWJF