Abstract:
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 SiO
2, Al
2O
3 content, lower Fe
2O
3 content, and intermediate TiO
2 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.