Linglong gold ore field is located in the northwest of Jiaobei Jiaolai fault uplift in Jiaoliao uplift of North China platform and in the east of Zhaoyuan-Yexian (Laizhou) metallogenic belt. The metallogenic belt belongs to the Jiaodong gold-iron-molybdenum-siderite-talc-graphite metallogenic belt, which is located in Linglong Mesozoic granite. The metallogenic belt is located in the northern margin of the east-west Qixia composite anticline in the Precambrian shield in eastern Shandong, and the whole mining area structure is controlled by the Tanlu deep fault. Mineralization is controlled by Toutouqing ductile shear zone in the southwest margin of Linglong Gold Mine, which is located in the footwall of Toutouqing shear zone.
1. Brief description of mine geology
(1) stratum
The exposed strata in this area are mainly Archean-Proterozoic Jiaodong Group and Fenzishan Group. Among them, the exposed part of Pengkuang Formation in Jiaodong Group is consistent with the spatial distribution of gold deposits in this mining area, which is formed by a set of submarine-erupted intermediate-basic volcanic rocks and a small amount of argillaceous and carbonate rocks metamorphism.
(2) Structure
There are mainly two structural systems in this area, namely, the east-west structural belt and the Neocathaysian structural belt. The mineralized surrounding rocks of Linglong Gold Mine are Linglong granite and residual rocks of Jiaodong Group. Orebodies and mineralization zones are mainly produced in structural alteration zones, that is, altered granite. The main structural feature of Linglong gold ore field is faults filling various rock walls (veins) or veins. The first-stage fault structure of the ore field is NE-trending, nearly EW-trending, NW-trending, NW-trending and NW-trending faults. The second stage belongs to Neocathaysia, and the faults in this stage are closely related to ore bodies. That is, Linglong fault and Jiuqu Putouqing fault have generally experienced two or more tectonic movements, which are beneficial to metasomatism and mineralization and often become their ore-hosting spaces.
(3) Magmatic rocks
Magmatic activity in the mining area is frequent and intense. Mainly divided into two periods. The first phase is the Neoproterozoic Sinian Linglong Superlattice Great Zhuangzi Unit, Luoshan Unit and Jiuqu Unit. The second stage is the Fushan unit of Wendeng Superunit in Mesozoic Indosinian period. The main rock mass in this area is Linglong granite, followed by guojialing granodiorite, which occurs in the form of bedrock or rock. The shallow part of the ore body occurs in Linglong granite and the deep part occurs in guojialing granodiorite.
2. A brief description of the characteristics of the deposit
(1) ore body characteristics
The whole region consists of hundreds of gold-bearing quartz veins and gold-bearing alteration zones of different sizes, and 547 gold-bearing quartz veins have been discovered. Its shape is bounded by Linglong fault, which is divided into two groups: east and west broom veins. The ore bodies in each vein zone are mostly located in the expansion part of the vein, the part from steep to slow, the intersection part of two groups of faults and the compound part of vein branches. Most ore bodies are lenticular, lentil, veined and irregular. Ore bodies have expansion and contraction, pinching and reappearance, branching and compounding, and most of them are in the shape of geese, herringbone and irregular arrangement. The main vein groups in this area are 108 vein group, 55-56 vein group, 36 vein group, 5 1-54 vein group, 9 vein group, 47-52 vein group, 10 vein group and 175 vein group.
The sample was taken from pulse number 55. Vein 55 occurs in vein group 55 ~ 56, located in the southeast of vein 108 and to the west of Linglong fault. The total length of vein group is about 4,000m, and the larger veins are No.55 and No.53. The general trend of vein group is 70 ~ 80 NE in the west and 40 ~ 50 NE in the east near Linglong fault, showing a northwest direction.
(2) Ore type and structure
According to the ore structure, main mineral assemblage and altered rock characteristics, the genetic types of ore can be divided into gold-bearing quartz vein type and gold-bearing altered rock type. Linglong gold deposit is dominated by gold-bearing quartz vein type, followed by gold-bearing altered rock type.
The ore texture is mainly granular texture and fragmented texture, followed by interstitial structure, filling structure, metasomatic texture, opacified structure, inclusion structure and metasomatic residual structure. Ore structures mainly include massive structure, veinlet disseminated structure and vein structure.
The specimen name should correspond to the Yanshanian period of the ore number DB004 of the time-pulse gold deposit.
Atlas of large ore specimens from typical mines in China
The ore specimen was collected from vein No.55 in the mining area. The specimen is grayish white, with granular, skeleton crystal, grid structure, lenticular, lentil and vein structure. Ore minerals mainly include silver-gold ore, natural gold, pyrite, chalcopyrite and so on. Gangue minerals are mainly timely and sericite. Gold grade is 8g/t.
Genetic types of Linglong gold deposit in Zhaoyuan City, Shandong Province: low-temperature hydrothermal genesis