The central and southern Beishan region,located at the convergence area of the Kazakhstan and Tarim plates,is one of the most important gold metallogenic provinces in northwest China.Gold deposits and spots are widely distributed in this area.Up till now,about 38 deposits and ore spots have been identified. Among them, the most important ones include Xiaoxigong, Xiaowannanshan, Xin Lao Jinchang, Shijinpo, Jinwozi, No. 210, Huaniushan, Huaxishan and Nanquan. These gold deposits and spots can be classified into 5 groups according to their host rocks. They are ① hosted by volcanic and volcaniclastic rocks, ② hosted by or related to granitoid intrusions,③ of skarn type, ④ hosted by Precambrain schists and ⑤ hosted by sedimentary rocks, respectively. Moreover, three mineralization concentration camps have been outlined:① Xiaoxigong Xiaowannanshan camp,② Xin Jinchang Huaniushan Jinchanggou camp and ③ Jinwozi 210 camp.Among the three camps, the first one occurs within the ancient Mazongshan uplift,whereas the other two are located along the active margin of the ancient continent.Systematic geological investigations indicate that the wall rocks of these gold deposits vary from place to place, but most of them show an intimate relation with the granitoid intrusions or Paleozoic felsic volcanic rocks. The forming processes of the gold deposits and spots are genetically related to Hercynian or Indosinian magmatic activities.The tectonic movement and the emplacement or eruption of the granitoid magma may result in the ascent and unloading of the deep seated ore fluids.The combined sulfur,oxygen,hydrogen and lead isotope data and petrological observations indicate that most of the gold deposits were formed by the mixing of magmatic fluids with heated meteoric water. These deposits are, therefore, believed to be products of Hercynian or Indosinian magmatism related to collision of the Kazakhstan and Tarim plates.
Acta Geoscientica Sinica
gold deposit gold metallogeny magmatic activities Hercynian Indosinian central southern Beishan region