Small-scale porphyry Cu-(Au) deposit, located in a Jurassic-Cretaceous volcanic-sedimentary basin. NE and NW-trending faults control the distribution of plutonic-volcanic belt. The deposit consists of veinlets and disseminations of gold and Cu and Mo sulphides in granite porphyry and quartz diorite. Cu minerals occur in the inner zone of the intrusion, whereas Au occurs in the outer zone. Alterations include K feldspar, silica, quartz-sericite, chlorite, and carbonate alterations. The deposit is closely related to silica alteration.

There are three metallogenic stages of this deposit, (1) Quartz-K-feldspar-polymetallic sulfide stage (stage Ⅰ), (2) quartz-polymetallic sulfide stage (stage II), and (3) quartz-calcite ± pyrite stage (stage Ⅲ). More than 3.4 × 104 tons of Cu and 1.1 × 103 Kg of Au; Cu grade 0.21–0.78 % and Au grade 3.52 –15.20 g/t. The main geological units in the Ershiyizhan District are the intrusive complex and the Ershierzhan Formation. From old to new, the lithologies in the intrusive complex are monzogranite (206.9 ± 1.8 Ma), granite (194.9 ± 1.3 Ma), quartz syenite (186.5 ± 1.3 Ma), and quartz monzonite porphyry (133.2 ± 1.0 Ma). Ershiyizhan is estimated to contain 77 copper orebodies and 56 gold orebodies, which are vein-like and have a thickness of 1–3 m. The mineralization of this deposit is characterized by plentiful veinlets, disseminated ores, and minor veins. The average Au and Cu grades are 1.99 × 10-6 and 0.34 × 10-2, respectively. Copper orebodies mainly occur in the quartz monzonite porphyry dikes with silicification and K-feldspathization alteration and the surrounding altered granites in the northern part of the mining area. Sericitized and silicified monzongranite is the primary host of gold orebodies, with the contact zones (both internal and external) between the Ershierzhan Formation and granite body also bearing evidence of gold mineralization.

The Cu orebodies are hosted in quartz monzonite porphyry dikes in the northern mining area, whereas the Au orebodies are situated in sericitized and silicified monzongranite. Au is commonly present as fractured (0.02–0.1 mm) grains or inclusions within chalcopyrite, pyrrhotite, and quartz.

Other Regions, Features and Areas containing this locality

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