北祁连早古生代洋盆是裂陷槽还是大洋盆——与葛肖虹讨论

北祁连早古生代洋盆是裂陷槽还是大洋盆,是一个有争论的问题。文中讨论了蛇绿岩中保存的代表大洋盆存在的印记。认为被夹持于华北地块和柴达木地块之间的北祁连早古生代造山带属于板块增生杂岩带,是由海洋岩石圈残片、消减杂岩、岛弧增生楔等组成的(或许还包括一部分残留陆块).指出北祁连蛇绿岩属于科迪勒拉型,暗示北祁连在早古生代时可能曾经是一个规模较大的洋盆,而非裂陷槽。华北地块和柴达木地块的规模很小,只不过是浩瀚海洋中散布的微小陆块而已。

THE NORTH QILIAN OCEANIC BASIN OF THE EARLY PALEOZOIC AGE: AN AULACOGEN OR A LARGE OCEANIC BASIN: A DISCUSSION WITH GE XIAOHONG

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.