The discovery of the manganese-bearing iron mineralization spots in the central segment of the Jinsha River and the prospecting potential

Located in eastern Xijinwulan-Jinshajiang suture zone and composed of the rock series of metamorphic basic volcanic rocks-clastic rocks, the original Xiongsong Group has been an object of long-term controversy as to whether it belongs to Precambria or not. Some iron mineralization spots were found during the investigation,and it is thus believed that iron mineralization was closely related to the volcanism with the simultaneous superimposition of the Indosinian monzogranite, implying an excellent metallogenic condition and prospecting potential. Iron ores mainly show massive, beehive and brecciated forms, with subordinate bubble, tumor and rope forms. Ore minerals are mainly manganese-bearing magnetite and subordinately hematite, limonite, malachite and relict pyrite of oxidation. The content of TFe from the sample can be over 50%, implying richness of Fe. High resolution LA-ICP-MS zircon U-Pb in situ dating yielded the age of 228.3±2.1 Ma for meta-basic basalt as the host rock of the ore deposit, which shows that the eruption age of Xiongsong Group related closely to mineralization is Middle Triassic. The chemical characteristics of the ore-bearing meta-basic volcanic rocks are similar to those of E-MORB, suggesting the tholeiite series and implying the tectonic setting of a small ocean basin. Meanwhile, the iron ore spots are well consistent with the ground high aeromagnetic anomalies. This may constitute an important clue for finding volcanic type manganese-bearing iron deposits in the middle Jinsha River region and its adjacent areas.