Banjiaoyuan Sn deposit, Qiyang Co., Yongzhou, Hunan, Chinai

Regional Level Types
Banjiaoyuan Sn deposit	Deposit
Qiyang Co.	County
Yongzhou	Prefecture-level City
Hunan	Province
China	Country

Total of 11 quartz-vein-type ore veins with different strike directions have been found in this deposit, and can be divided into two groups, i.e., 3 are nearly NS-trending, and the other 8 are NE-trending. All the veins are controlled by faults, and cut across the intrusions. They have length of 500–1060 m, depth of 200–500 m, thickness of 0.45–2.15 m, and average ore grade of 0.48 wt% of Sn.

It is a quartz vein type tin deposit with great resource potential confirmed by geological investigation in recent years. The mining area has a long history of private mining. The longest tunnel is more than 2 km long, with the total length of tens of kilometers. The loss of historical tin mining resource reserves is more than 20,000 tons, and the retaining tin resource reserves are more than 10,000 tons. Overall, the resource reserves of this deposit reached medium size.

The stratigraphy of the mine area is mainly Ordovician, widely distributed in the uplifted section around the Yangmingshan composite granite pluton, which can be divided into the Qiaotingzi Formation (O1q), Yanxi Formation (O2y) and Tianmashan Formation (O3tm) from the bottom upward according to lithological assemblage. It mainly consists of a set of thick shallow metamorphic sandstone, slate and carbonaceous slate in the shallow marine phase. The Late Ordovician Tianmashan Formation (O3tm), whose lithology is dark gray medium-thick laminated weakly metamorphosed fine sandstone with slate, is exposed within the mine area, distributed around the granite body, with brittle lithology and developed joints and fissures, which is one of the enclosing rocks of the tin vein. Thirteen ore veins have been found in the mining area.
The mineralization of the Banjiaoyuan tin deposit can be divided into three stages: greisen (I), cassiterite-quartz vein (II), and late barren quartz vein (III). The muscovite 40Ar/39Ar plateau age of stage I (215.51 ± 0.87 Ma), quartz fluid inclusion Rb-Sr isochron age of stage II (214.2 ± 3.1 Ma) and cassiterite U-Pb lower intercept age (215.7 ± 1.3 Ma) indicate that they are the products of late Indosinian tectonic magmatism.

Other Regions, Features and Areas containing this locality

References