Geochemical Characteristics and Genesis of Cherts from Mayile Ophiolitic Mélange in West Junggar, Northern Xinjiang

Mayile cherts of early Paleozoic generally occurred in ophiolitic mélange. Their provenance and sedimentary environment are discussed based on the petrography and geochemistry of the silicolites in the cross section of the Mayile ophiolites. The cherts are mainly purple and composed of microcrystalline authigenic quartz and implicit eutectics. According to geochemical characteristics, the samples are all influenced by the acidic volcano tuff and are probably the product of both the biochemical and volcanic process. Cherts of this type generally have higher SiO₂, Al₂O₃ content, lower Fe₂O₃ content, and intermediate TiO₂ content. Integrating the geological occurrence, petrography and the geochemical characteristics of those cherts, it is believed that the cherts are formed in a tectonic setting above the subduction zone rather than an open oceanic environment.