Multi-isotope dating to constrain gold mineralization in the Xiadian deposit, Jiaodong peninsula

The Xiadian gold deposit, located in the Zhaoyuan-Laizhou belt, Jiaodong peninsula, is characterized by disseminated and stockwork ores enclosed by hydrothermally altered wallrocks. The exact age and the genesis of the gold deposit remain controversial. The wallrock Linglong granite represents the earliest magmatic event at Xiadian, and yielded a zircon LA-ICPMS U-Pb age of 159.5 0.9 Ma (2 sigma, MSWD=0.63). Subsequent geologic events were recorded by minor amounts of quartz-pyrite-molybdenite veins which yield a weight average Re-Os molybdenite model age of 125.9 0.80 Ma (2 sigma, MSWD=0.23) by molybdenite Re-Os method. The formation of such veins was close to the emplacement of adjacent Guojialing granodiorite (126130Ma), and thus may be considered as a product of post magmatic hydrothermal activity. Gold mineralization took place at 120.0 +/- 1.4 Ma (2 sigma, MSWD=0.59), determined by LA-ICPMS U-Pb dating on hydrothermal monazite from quartz-polymetallic sulfide veins. Prior to and post mineralization, voluminous hydrothermally altered porphyritic diorite and fresh quartz diorite porphyry dykes were emplaced, which yielded U-Pb ages of 121.3 +/- 1.4 Ma (2 sigma, MSWD=0.28) and 115.8 1.9 Ma (2 sigma, MSWD=0.71), respectively. Based on these geochronological data, the genesis of the Xiadian deposit might be related to the craton destruction and lithosphere thinning in the eastern North China Craton.