Xinglongshan Ore Block, Shuangjianzishan Ag-polymetallic deposit, Bairin Left Banner (Balin Zuoqi), Chifeng City (Ulanhad League; Chifeng Prefecture), Inner Mongolia, Chinai

Regional Level Types
Xinglongshan Ore Block	Ore Deposit
Shuangjianzishan Ag-polymetallic deposit	Deposit
Bairin Left Banner (Balin Zuoqi)	County
Chifeng City (Ulanhad League; Chifeng Prefecture)	Prefecture-level City
Inner Mongolia	Autonomous Region
China	Country

The exposed strata in the Xinglongshan ore block include the Lower–Middle Permian Dashizhai Formation, Middle Jurassic Xinmin Formation, and Upper Jurassic Manketouebo Formation. Except for a small amount of rhyolite porphyry veins exposed on the surface, other granitic intrusions, including granite, biotite granite, and syenogranite, are all concealed below 500 m of the ore block surface. The fault structures, including NE-, NW-, and NEE-trending faults, are well-developed. According to the direction of orebodies, the orebodies in the Xinglongshan ore block are mainly divided into (1) NW-trending Ag–Pb–Zn (Cu) ore vein group, (2) NNW-trending Ag–Pb–Zn orebodies, and (3) NNE-trending Ag–Pb–Zn orebodies. In addition, small amounts of near E–W-trending Au-bearing Ag–Pb–Zn orebodies are also developed in this ore block.

(1) The NW-trending Ag–Pb–Zn (Cu) ore vein group: The orebodies in the ore vein group distributed in the central and eastern parts of the ore block are controlled by a NW-trending thick and large fractured zone. The ore-hosting rocks are slate and silty slate of the Lower–Middle Permian Dashizhai Formation. The overall strike of the ore-vein group is 300°–310°, inclined towards the southwest, with dip angles of 50°–65° and a length > 2000 m and a width > 1200 m. The ore-vein group is mainly composed of Ag–Pb–Zn orebodies and Ag–Zn orebodies, with a small amount of Zn orebodies and Ag–Cu–Pb–Zn orebodies. The individual orebodies occur as veins, usually having a length of 100–800 m and a thickness of 1–10 m, with a maximum thickness exceeding 100 m. The ore structure is mainly of fine-vein, stockwork, disseminated, and dense disseminated. The major wall-rock alteration includes silicification and chloritization, with minor sericitization. These altered minerals mainly occur in the form of fine veins and stockworks within a thick NW-trending alteration zone, with minor veins and crumbs of quartz. The grade of the Ag–Pb–Zn orebodies is relatively low, with average grades of 98 g/t Ag, 1.6% Zn, and 0.6% Pb, respectively. The Ag–Cu–Pb–Zn orebodies usually occur at the top of the ore-vein group, with a controlled length greater than 300 m and a thickness of 0.6–2.8 m. The Ag–Cu–Pb–Zn orebodies have average grades of 263 g/t Ag, 0.7% Cu, 2.2% Zn, and 0.9% Pb, respectively.

(2) The NNW-trending Ag–Pb–Zn orebodies: These orebodies, mainly distributed in the central and eastern parts of the ore block, are controlled by NNW-trending faults. The overall trend of these orebodies is approximately 310°, with a thickness of 3–15 m and a length of > 400 m. The ore structure is mainly of massive and vein. The wall-rock alteration is characterized by silicification and carbonation, with minor chloritization, and quartz and calcite mainly occur as fine veins within the orebodies and within a range of no more than two meters nearby. The NW-trending Ag–Pb–Zn orebodies have average grades of 400 g/t Ag (some up to 10,000 g/t), 2.8% Zn, and 4.3% Pb, respectively.

(3) The NNE-trending Ag–Pb–Zn orebodies: These orebodies, distributed in the eastern part of the ore block, are composed of five parallel orebodies. They are controlled by NNE-trending faults, which dip to NWW at > 65°. The ore structure is mainly of massive and vein. The types and distribution characteristics of wall-rock alteration are similar to those of the NNW-trending orebodies. These orebodies have a thickness of 2–6 m and a control length > 600 m, with average grades of 400 g/t Ag, 2.5% Zn, and 3.2% Pb, respectively.

Other Regions, Features and Areas containing this locality

References