Redefination and ore-forming significance of Maeryang Forming, Taxkorgan, Western Kunlun Mountains

The Taxkorgan large-scale iron metallogenic belt is located in the western part of Kunlun orogenic belt. Research on metamorphic rocks shows that the protolith of the iron-bearing strata is a assemblage of bimodal volcanic rocks-clastic rockscarbonate rocks formation. The strata have undergone widespread greenschist facies metamorphism and multi-superimposed deformation. The meta-andesite in Laobing area yielded an U-Pb ziron age of (603±10) Ma, suggesting that the eruption age of volcanic rocks is early Sinian. Combined with other age data available, the authors redefined the iron-bearing strata as "SinianCambrian Terreneuvian Maeryang Formation" (Z€₁m.), which doesn't belong to the previously defined "Paleoproterozoic Bulunkuole Group". The formation of the bimodal volcanic rocks proved that there was an extensional tectonic event in Taxkorgan area from Sinian to early Cambrian. Discrimination of tectonic setting on the metamorphic volcano-sedimentary formation indicates that the iron-bearing strata were formed in the continental margin rift. The gypsum (Ba)-iron formation was the volcanosedimentary response to the changes of "Marinoan Snowball Earth"'system after late Neoproterozoic glacial event.