Mo: 0.091 % molybdenum porphyry deposit

The Rongga Mo deposit lies between the Yanhu fault and the Xialacuo fault on the southern margin of the western Bangong-Nujiang metallogenic belt. Strata exposed in the mining area are dominated by the Middle-Upper Jurassic Lagongtang Formation (J2-3l), with minor Quaternary cover (Q). The Lagongtang Formation consists mainly of calcareous sandstone and fine-grained feldspathic quartz sandstone interbedded with argillaceous siliceous rocks. Thin limestone beds occur locally, and the formation has been interpreted as a submarine turbidite-fan succession deposited on a continental slope. Igneous rocks are widespread and occur mainly as stocks and dikes of granite porphyry (γπ), monzogranite porphyry (monzonitic granite porphyry; ξπ), diorite porphyry (δµ) and granite (γ). Eight molybdenite orebodies (Mo-I to Mo-VIII) have been constrained mainly by drill holes ZK001, ZK002, ZK003 and ZK101. They strike NW, dip gently SW and occur as tabular to stratiform or lens-like bodies that are vertically stacked and locally thicken adjacent to fracture zones. This geometry is consistent with strong control by NW-trending structures. The orebodies extend ∼ 96–160 m along strike and ∼ 100–320 m down dip. Grades range from 0.063-0.123 wt% Mo (mean ∼ 0.084 wt%); Mo-II is highest (0.123 wt% Mo), and Mo-I, Mo-V and Mo-VI are relatively enriched (0.092–0.098 wt% Mo). On this basis, the quartz-vein system at Rongga is divided into six vein types: DQ, A, AB, B, D and LQ veins. These comprise pre-ore to earliest deep quartz veins, early quartz-pyrite veinlets, transitional quartz-pyrite-molybdenite veins, main-ore quartz-molybdenite veins, late quartz-pyrite ± polymetallic sulfide veins and late weakly mineralized quartz veins.

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