The dark gray limestone in the mining area is produced in layers, the strata strike northeast-southwest, the dip angle is 20°–90°, and the degree of weathering is moderate to strong. The diabase is the intrusive rock of limestone. In the contact zone between limestone and diabase, layered marble appears, the bedding direction of which is consistent with that of limestone. The protolith of marble is limestone. The dip angle of the limestone is too small or too large, only marble occurs in the contact zone between diabase and limestone, and no stratified tremolite nephrite veins are found. The dip angle of the limestone is between 60° and 70°, the diabase invades along the limestone layer, and stratified tremolite nephrite veins appear in the metamorphism of marble. The stratified tremolite nephrite ore body is distributed in layers of different thickness, and the direction of stratified tremolite nephrite veins is consistent with the direction of the marble bedding. There is a sharp contact between the stratified tremolite nephrite ore body and the marble, and sometimes there are large cracks between the stratified tremolite nephrite veins and the marble.

The metamorphism in the mining area is primarily characterized by hydrothermal metasomatism and contact metamorphism. The ore-forming process can be summarized into three stages: (1) Basic magmatic intrusion (diabase), with zircon U-Pb dating indicating a Permian age [17]. (2) Thermal metamorphism of limestone, transforming it into marble. (3) Infiltration of Mg- and Si-rich hydrothermal fluids along the bedding planes of the marble, leading to metasomatism and the subsequent formation of the nephrite deposit.

Other Regions, Features and Areas containing this locality

References