Wajiertage Mine, Wajiertage, Bachu Co. (Maralbexi Co.; Maralbeshi Co.), Kashi Prefecture (Kashgar Prefecture; Qeshqer Prefecture), Xinjiang, Chinai

Regional Level Types
Wajiertage Mine	Mine
Wajiertage	Complex
Bachu Co. (Maralbexi Co.; Maralbeshi Co.)	County
Kashi Prefecture (Kashgar Prefecture; Qeshqer Prefecture)	Prefecture
Xinjiang	Autonomous Region
China	Country

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Sinian-Carboniferous alkaline magmatic complex, intruded into metamorphic rocks and composed of pyroxenite, gabbro, syenites and carbonatite veins and lenses. The complex is mined for its vanadium content (in vanadiferous titaniferous magnetite) and has also been prospected as a potential REE resource.

Carbonatite dykes constitute an integral component of the Wajilitage complex and serve as the principal host for REE mineralization. They are predominantly emplaced within the layered mafic–ultramafic intrusions, particularly pyroxenite and gabbro. These dykes define a ring-like system around the mafic–ultramafic body, forming an east–west-trending carbonatite zone that extends for several kilometers). Individual dykes range from narrow veins to meter-scale bodies and dip steeply (70–80◦ ) inward toward the complex interior. Later diabase dykes crosscut the carbonatite dykes; combined with the emplacement ages of the layered mafic–ultramafic intrusions and the diabase dykes, this crosscutting relationship constrains the age of the carbonatite dykes to between 283 and 272 Ma. This inference is corroborated by monazite U–Pb geochronology, which dates a ring-shaped carbonatite dyke at 272 Ma. The carbonatite suite is dominated by dolomite carbonatite, with subordinate calcite carbonatite; both varieties occur within the ring-like dyke system and are spatially associated. The adjacent wall rocks, mainly pyroxenite and gabbro, display local fenitization. The Bachu REE deposit is hosted by these carbonatite dykes. The deposit contains a measured resource of approximately 300,000 t of TREO. Primary monazite-(Ce) and bastnäsite-(Ce) occur as euhedral or interstitial grains in the carbonatite, together with apatite and accessory Nb-bearing minerals. Although the major carbonate minerals contain only tens to hundreds of ppm total REEs, the carbonatites as a whole are strongly enriched, indicating that carbonate fractionation concentrated REEs into the residual carbonatitic melt. A second and locally much higher-grade style of mineralization occurs as red REE-rich veins that cut the dolomite carbonatite. These veins contain up to approximately 20 wt.% total REEs and are characterized by barite + celestine + fluorapatite + monazite-(Ce), with minor dolomite, pyrite, quartz, and magnetite. Dolomite carbonatite and the red hydrothermal veins are the principal focus of this study.
Collectively, these results support a two-stage model for the Bachu REE deposit (Figure 9). During the first stage, mantle-derived carbonatitic melts influenced by recycled crustal components underwent fractionation, precipitating Py1 and primary REE minerals while progressively concentrating REEs in the residual melt. During the second stage, exsolved hydrothermal fluids cooled and became more oxidized, leading to the formation of Py2, barite, celestine, fluorapatite, and monazite-(Ce), accompanied by REE remobilization and high-grade vein mineralization.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List

17 valid minerals.

Rock Types Recorded