Indosinian gold mineralization and magmatic-hydrothermal evolution of the Hadamengou gold deposit at the northern margin of the North China Craton: Constraints from K-feldspar laser Ar-40/Ar-39 dating

摘要

The Hadamengou gold deposit, which is located in a high-grade metamorphic terrane at the northern margin of the North China Craton, is characterized by K-feldspar-quartz vein gold mineralization. The Ar-40/Ar-39 dating of hydrothermal K-feldspar indicates that the mineralization formed over 45 Ma commencing at 243.5 +/- 1.3 Ma and ending at 199.0 +/- 0.8 Ma. The Pb, C and O isotope compositions and the geochronology of the gold-bearing K-feldspar-quartz veins imply a close genetic association between the gold mineralization and alkaline magmatism, which are both products of the Indosinian alkaline magmatic event caused by the extensional tectonic setting that prevailed during the late Hercynian collisional orogeny. We propose an Indosinian phase of gold mineralization in addition to the abundant mineral deposits formed during the Yanshan Epoch.