The Gannan-Shaanxi-South Hubei (Qinba-style) sedimentary barite deposit is located at the margin of Taipei in the Yangtze region, and it is located at the junction of Gansu, Shaanxi, Sichuan, Chongqing, Hubei, and it is distributed in a strip shape near east-west. The types of deposits in the area are sedimentary and layered. The known deposits include the Dongfenggou barite ore deposit in Wenxian County, Gansu Province, and the Liulin barite ore deposit in Suizhou City, Hubei Province.

1. Regional geological background

Early Sinian-Early Cambrian, the Taipei margin of the Yangtze land is a rift zone of continental margins, and a deep-water reducing environment sedimentary basin mainly composed of rift basins, which deposits black rock series and manganese ore, containing vanadium, molybdenum, uranium, etc. Minerals such as polymetallic barite. The toxic barite-barite deposit is widely developed in the Lower Cambrian black rock series in the Qinba area, which is an important barite ore cluster in China. The ore cluster area is distributed along the north side of the Dabashan fault and is controlled by the rifting tectonic environment of the southern Qinling continental margin.

At present, more than 40 barite, poisonous barite + barite deposits (points) have been found in the area. The ore deposits are layered or layer-like in siliceous rocks in the lower Lower Cambrian, and the ore-bearing horizons are stable. The ore deposits have the characteristics of syngenetic sedimentation, and the ore body is obviously controlled by lithology and lithofacies.

With the development of the Sinian Rift in the South Qinling area, the Cambrian-Ordovician has developed into an ancient trough of considerable scale, and under the restrictions of base islands and underwater uplifts in the Qinling Sea, a more typical Stranded basin. The west and the west Qinling Mountains communicate with each other, forming a deep, deep ocean trough. Under the background of this tectonic environment, conditions have been created for the formation of marine jet-sedimentary toxite-barite deposits.

2. Metallogenic characteristics of ore clusters

The west of the mining area starts from Wenxian County in the south of Gansu, and passes through Ankang, Pingli, Xunyang, Zhenpingping County in the south of Shaanxi and Chengkou and Wanyuan in the northeast of Sichuan to Sui County and Jingshan County in the north of Hubei. It is distributed in a narrow strip from northwest to west, south to east, and east to east. The tectonic location is located at the edge of Taipei in the Yangtze Land. Most of the barite deposits (including poisonous rocks) are located at the bottom of the Lower Cambrian, between the siliceous construction and the carbon slime construction. The ore deposits are mostly of sedimentary origin, which are layered, layer-like, and lenticular. The deposits are mainly large and medium-sized. The floor is mostly black siliceous rock, and the roof is generally black carbonaceous shale.

The barite ore deposits in the ore-concentration area are mainly present in the Lower Cambrian Lujiaping Formation. The ore-bearing strata have been in order from old to new: a lithological section is a set of siliceous rocks, and the lower part is a thick siliceous rock. A small amount of dolomitic and dolomite limestone lens bodies; medium-thick and thin-layered siliceous rocks, colloidal nodule containing nodules, ore-bearing strata of toxicite and barite ore. The second lithology section is a set of slate, and the lower part is black carbonaceous silty slate; the upper part is gray mudstone and dolomitic slate with a thin layer of limestone. It can be seen that the barium-bearing minerals are mainly present in the transition zone from biochemical deposition to detrital deposition of carbonates and siliceous rocks, and are also the transition site of weak reduction to strong reduction environment. The underlying strata constructed by the ore are a set of acid volcanic rocks, volcanic clastic rocks, tuffs, etc., which are important sources of barium. It should be noted that the barite production horizons in the Dabashan area are not limited to the Lower Cambrian, and all the way up to the Lower Silurian, there are barite-containing horizons. For example, the barite in Ankang, Xunyang and other counties of Shaanxi is produced in the Upper Cambrian-Ordovician and Lower Silurian. A series of toxicite deposits are distributed in the area and are produced on the edge of the platform. They are controlled by the Dabashan deep and large fault. The Lower Cambrian Lujiaping Formation is the main production stratum of toxicite deposits.

3.Typical deposit

Liulin barite factory in Suizhou City, Hubei Province. The deposit is located in the south of Suizhou City, Hubei Province, starting from Wangjiawan of Liulin Commune in the west and extending to Luoyangdian in the east.

(1) Regional geological background: The deposit is located at the southern edge of the Qinling Trough.

(2) Metallogenic environment: The Cambrian Dayanjiao Formation is a barite-bearing rock series. To the north of Xiangda fault, the northeast wing of Tanjiamen complex syncline and Zaoshuyu complex syncline. The tectonic activity in the area is strong, and the main features are linear inversion, oblique folds and thrust faults. The general direction of the tectonic line is northwest-southeast. The Paleozoic and its former strata have experienced a relatively low degree of metamorphism. The folds in the area are mainly linear. In the western part of the Liuhe Bay, the fold axis is about 320 ° northwest to 130 ° southeast, the axis is inclined to the southwest, and the hub is slightly inclined northwest. The faults in the area are mainly northwestward compressive faults, the faults are about 320 ° northwest, tend to southwest, and the dip angle is large, which can reach more than 80 °.

(3) Orebody distribution and occurrence: Barite orebody is produced in the upper part of the lower section of the Dayanjiao Formation of the Cambrian. Laminar, layer-like output. The bottom plate is a thin layer of vermiculite and sericite quartz slate. The roof of the ore layer is a thin layer of carbonaceous vermiculite and sericite quartz slate in the middle of the Dayanjiao Formation. The ore body is produced in strict stratified layers, and extends approximately 20km intermittently. The western trend is about 310 ° northwest; the eastern trend is about 290 °, and it is generally inclined southwest, southwest, and west.

(4) Ore structure and structure: The ore is mainly a microcrystalline structure and a scale crystalline structure. Dense block structure, strip-like, plate-like structure.

(5) Types of ores and mineral components: The natural types of ores are mainly dense and massive, followed by dolomitic ores and banded ores. The main minerals of the ore are barite, followed by quartz, sericite, and carbonaceous. BaSO4 content is 50% to 98.8%.

(6) Physical and chemical conditions of ore formation: δ34S barite is + 38.72 × 10-3, pH value is 6.8, and Eh value is 352mV

(7) Genesis analysis of the deposit: The deposit is located at the bottom of the Lower Cambrian. In the area of Suixian, Hubei, it is composed of volcanic construction and sedimentary construction and volcanic sedimentary construction from the Proterozoic to Lower Paleozoic. In the Lower Cambrian Dayanjiao Formation, there are phosphorous nodules siliceous slate, barite ore layer, carbonaceous siliceous slate, and carbonaceous quartz sericite slate with limestone lens bodies. The thickness is 132-240m. . According to Li Wenyan's research, the rare earth content of barite ore is characterized by the enrichment of light rare earth elements, with a loss of tritium, which seems to be related to the remelting of the crust, indicating that the volcanic source came from the continental rift tectonics environment. The ore-forming materials come from the volcano-gas-liquid spurt. The genesis type of the deposit is sedimentary.