U–Pb zircon and geochemical constraints on age and genesis of granitoids from the Jinchang Au deposit in Heilongjiang, NE China

Abstract

The Jinchang Au deposit is a large‐sized deposit in Heilongjiang Province, and mineralization is closely related to the Early Cretaceous granitoids. The orebodies occurred within granite, granite porphyry, granodiorite, and diorite. Gold mineralization type consists of crypto‐explosive breccia, vein, and veinlet‐disseminated types. In this paper, we present U–Pb age as well as major and trace element geochemistry of intrusive bodies from the Jinchang deposit. Our study indicates that granite, granite porphyry, and granodiorite from the Jinchang deposit are calc‐alkaline to high‐K calc‐alkaline with geochemical characteristics of typical island‐arc environment. Diorite and diorite porphyrite show calc‐alkaline affinities with geochemical characteristics of adakite or adakitic rock. Concordant zircon U–Pb ages of 184.69 ± 0.98 Ma and 203.62 ± 0.86 Ma are obtained from granites; 190.4 ± 4.7 Ma, 205.88 ± 0.95 Ma, and 109.0 ± 2.4 Ma are obtained from granite porphyry, granodiorite, and quartz diorite. Combined with previous geochronological data, the diagenetic ages for granitoids in the Jinchang deposit are mainly focused on 2 episodes: 110 ~ 120 Ma and 185 ~ 200 Ma. The corresponding tectonic settings for the 2 episodes of magmatic activities are subduction of the Izanagi Plate towards the Eurasian Plate, and post‐collision system after the collision of North China Craton and Jiamusi‐Khanka Massif, respectively. We suggest that the magmatism (110 ~ 120 Ma) formed adakitic diorite and diorite porphyrite and closely associated with mineralization. Upwelling mantle results in partial melting of the lower crust and extract and transfer metals to the upper crust for further concentration. It also reveals that Jinchang Au deposit is an adakite‐associated deposit.

The 40Ar/39Ar dating of quartz: new insights into the metallogenic chronology of the Jinchang gold deposit and its geological significance

“…Among them, the granite porphyry records intense phyllic alteration, accompanied by abundant mineralization 19 . The emplacement age of the granite porphyry has been well constrained, concentrated at 110~113 Ma 19,20 which is broadly consistent with the time of the gold mineralization. We therefore infer that the gold mineralization is spatio-temporally and genetically associated with the granite porphyry.…”

“…3a,b) from Jinchang deposit 16 , indicate the ore metals and fluids came primarily from a magmatic source. Previous geochronological studies of intrusive rocks in the Jinchang deposit have shown that at least two periods of magmatic activity have been recognized in the mining region, including widely outcropping early Mesozoic (185~210 Ma) 19–21 granite, diorite, granodiorite and syenogranite, as well as the locally distributed late Mesozoic (110~120 Ma) 19,20,23 granite porphyry and diorite porphyry. Among them, the granite porphyry records intense phyllic alteration, accompanied by abundant mineralization 19 .…”

“…Mineralization in the district is predominantly hosted by the widespread early Mesozoic (185~210 Ma) 19–21 granite, diorite, granodiorite and syenogranite (Figs 1c, 2). However, the locally distributed late Mesozoic (110~120 Ma) granite porphyry and diorite porphyry were thought to be temporally and genetically associated with the gold mineralization 18–20,22,23 . Structurally, the ore district is characterized by widely developed NE-, NW-, N-, and E-trending linear fractures with subordinate ring and radial faults (Fig.…”

Re–Os Pyrite Geochronological Evidence of Three Mineralization Styles within the Jinchang Gold Deposit, Yanji–Dongning Metallogenic Belt, Northeast China

“…The intrusive rocks comprise diorite, granite, graphic granite, granodiorite, and diorite and granite porphyries. The granitoids are calc-alkaline and high-K calc-alkaline with geochemical affinities to typical island-arc intrusive rocks [20,21]. The diorites and diorite porphyries are calc-alkaline and have geochemical affinities to adakites [20].…”

“…Diorite, graphic granite, and granite are widely exposed within the Jinchang Deposit and yield U-Pb ages of 209-185 Ma, indicating that they were emplaced after collision of the North China Craton and the Jiamusi-Xingkai Block [19,20,22,23]. These rocks are the main hosts of the ore body and are extensively altered adjacent to the mineralization.…”