It is debated whether the north Qilian oceanic basin of the early Paleozoic age is an aulacogen or a large oceanic basin. Imprints preserved in ophiolites probably representing a large ocean are discussred in the paper. It is proposed that the north Qilian Orogen of the early Paleozoic between North China block and Qaidam block is a plate accretion melange belt, which consists of relict oceanic lithosphere, subducted complex and island arc-accreted wedge (or a few remnant micro-continental blocks). It is pointed that the north Qilian ophiolites are of Cordillera type, implying that the north Qilian was probably a large-scale ocean basin in early Paleozoic, not an aulacogen, and North China block and Qaidam block were very small at that time, being micro-continental blocks in vast ocean.
Zhang Qi,Wang Yan,Qian Qing. THE NORTH QILIAN OCEANIC BASIN OF THE EARLY PALEOZOIC AGE: AN AULACOGEN OR A LARGE OCEANIC BASIN: A DISCUSSION WITH GE XIAOHONG[J]. Chinese Journal of Geology, 2000, (1): 121-128.