Dashigou - unikatni lozisko Mo a REE v centralni Cine

The unique Dashigou Mo-REE deposit is the most significant part of the Huanglongpu carbonatite complex hosting the Dashigou, Yuantou, Shijiawan and Taoyuan molybdenum deposits. The complex lies in the Qinling orogenic belt forming the southern edge of the North China block. The individual ore bodies (up to 20 x 800 m in size) extend discontinuously over a total distance of about 6 km. Carbonatite dykes consist mostly of calcite, followed by less abundant or minor minerals like feldspar, barite, pyrite, galena, sphalerite, molybdenite, REE-fluoro-carbonates, monazite, xenotime, allanite and a wide range of other accessory minerals. The molybdenite, as an uncommon mineral for carbonatites, occurs in two main populations: PM1 - as primary magmatic disseminated grains in close association with REE minerals, and PM2 - forming secondary intergranular coatings and fracture fillings. The REE minerals are represented by 2 independent groups: G1 is enriched in light REE, whose relative proportions increase from parisite-(Ce) [(La/Nd)n = 1.1-2.0] to bastnasite-(Ce) and monazite-(Ce) [(La/Nd)n = 1.7-2.2 and 2.3-4.5], and G2 enriched in heavy REE, of which relative proportions increase from xenotime [(La/Nd)n = 0.2-0.6] to allanite [(La/Nd)n = 0.7-1.0]. The wholerock compositions are characterized by the highest Mo and heavy REE concentrations so far reported for carbonatites or any rock type worldwide: up to 3800 ppm Mo, 1700 ppm HREE (Y+Gd...Lu) and (La/Yb)n = 1.0-2.6.