Abstract: Thelate Paleozoic silicalitesare covered the ophiolites with thin layered shape, which is generally and often transformed into lenticular structurein oceanic subduction and tectonic emplacement process in Darbut, West Junggar.In order to explore the provenance and sedimentary environment, the petrography and geochemistry studiesabout these silicalitesfrom the cross section of the Darbut ophiolites have been carried out in this paper. The results show that these silicalitesmainly show purple and gray color, which arecomposed of microcrystal authigenic quartzsand cryptocrystals. And the microcrystal authigenic quartzs arevisible observed by microscope. According to the whole rock geochemical characteristics, these silicalites can be divided in biochemistry silicalites and siliceous rocks with volcano tuff, with some of them have the transition characteristics of both two types. The biochemistry silicalites generally have high Si and Fe contents, low Al, Ti and total REE values, with low contents of trace elements, some of them show negative Ce anomalies, and part of them have weak even positive Ce anomalies. The siliceous rocks with volcano tuffare generally charactered by high Si, Al, Ti contents, low Fe value, with obvious increasing trend of acidic volcano material components. Integrating the geological occurrence, petrography and geochemical characteristics, it is believed that these silicalites are formed in marginal ocean basin rather than open oceanic environment. This result is agreed with the SSZ settings of previous study, having important significance to recognize the tectonic environment of the ophiolite.