The genesis of the calcirudites from the Permian Maomaolong Formation in the Xiahe district, Gansu

The calcirudites from the Upper Permian Maomaolong Formation in the Xiahe district, Gansu occur signifi-cantly in the Central Qinling fault depression, and comprise two types:autochthonous and allochthonous. These calcirudites are not considered to be tectonic mélanges; the thick lenticular calcirudites appear as chaotic olistostromes and/or collapsed circum-continental talus, passing upward into the debris flow deposits, which are characteristic of the platform slope deposits on passive continental margins, and differ greatly from the fractured mélanges as thrust sheets in the subduction zones.