Stable Isotopic Geochemical and Geochronological Constraints on the Formation of the<scp>S</scp>hihu Gold Deposit: The Intracontinental Metallogeny of the<scp>T</scp>aihang<scp>T</scp>ectonic Belt, Eastern<scp>C</scp>hina

Abstract

Abstract The Early Cretaceous S hihu gold deposit is located in the northern segment of the T aihang T ectonic belt, which extends across the central part of the N orth C hina C raton. The deposit is hosted predominantly by the Archean metamorphic crystalline units, and is spatially and temporally related to quartz diorite porphyry present extensively throughout the gold deposit. We studied the geology, geochronology and stable isotopic geochemistry. Zircon U – P b LA–ICP – MS ages of the quartz diorite porphyry at deposit range from 134 ± 1 to 131 ± 2 Ma, which are coeval and probably genetically related to the mineralization. The majority of the sulfides of the gold deposit have δ 34 S values ranging from −1 to 2‰, which suggest an homogeneous magmatic source. In addition, the isotopic compositions of δ 18 O fluid and δ 18 D fluid vary from 2.1 to 7.0‰ and −93 to −65‰, respectively, suggesting that the magmatic fluids mingled with meteoric water. The P b isotopic analyses reveal that both the ore‐forming materials and the quartz diorite porphyry originated from the lower crust and may have been mixed with mantle material. The 87 S r/ 86 S r i and 143 Nd/ 144 Nd ( 143 N d/ 144 N d) i ratios for the quartz diorite porphyry demonstrate that there was mixing of two end‐member (crust and the mantle) isotopic compositions. These results suggest that the ore‐forming fluids and materials were derived from lower‐crustal melting induced by mantle processes. Processes associated with the formation of the S hihu gold deposit differ significantly from those that characterize orogenic gold deposits, and instead are representative of formation in an intracontinental tectonic environment.