中国蛇绿岩的分布、时代及其形成环境

中国蛇绿岩分布很广，主要在中国的西部，西南部和北部，中部和南部较少，蛇绿岩形成的时代可分为元古宙，早古生代、晚古生代和中－新生代四个时期，中国元古宙蛇绿岩分布零星。星生宙蛇绿岩主要分布在古亚洲洋，秦祁昆洋，古特提斯洋，新特提斯洋和和环太平洋等5个区域，古亚洲洋蛇绿岩位于塔里木和华北地块之北的中国北方，秦祁昆洋位于塔里木、华北和扬子地块之间，古特提斯洋和新特提斯洋位于中国的西南地区，环太平洋带有东北和台湾的蛇绿岩，中国蛇绿岩的地和玻安岩产出，指示产于消减带之上的构造环境，在这些蛇绿岩中也有MORB产出，可能是弧后盆地环境的，也可能有正常大洋岩石圈碎片的残留。古特提斯蛇绿岩MORB发育，而减少与消减作用有关的岩石组（IAT和玻安岩），推测形成在陆间洋盆环境。

The distribution of time and space of Chinese ophiolites, and their tectonic settings.

Ophiolites are widely distributed in China, particularly in the western, southwestern and northern parts of the country, and rarely in the middle and south parts. The ophiolites fall into four principal age groups: PrQterozoic, early Paleozoic, late Paleozoic and Mesozoic-Cenozoic. The Proterozic ophiolites occur sporadically in China. The Phanerozoic ophiolites in China are grouped into five series, namely the Paleo-Asian Ocean series, the Qinling-Qilian-Kunlun Ocean series, the Paleo-Tethyan series, Neo-Tethyan series and the Circum-Pacific ophiolites. The Paleo-Asian Ocean ophiolites crop abundantly out in the northern part of China north of Tarim and the North China Block. The Qinling-Qilian-Kunlun Ocean lies among Tarim, the North China and Yangtze blocks. The Paleo- and Neo-Tethyan oceans are confined to the southwest China, and the Circum-Pacific series include the NE China and Taiwan ophiolites. Chinese ophiolites are geochemically complex and two or more lava types commonly occur within a given ophiolite sequence. Most ophiolites in the Palaeo-Asian, Neo-Tethyan and Circum-Pacific belts contain IAT and/or boninite indicating a suprasubduction zone origin. MORB lava in these bodies may have been originated in back-arc basins or may represent relict fragments of normal ocean lithosphere. Paleo-Tethyan ophiolites have mostly MORB lavas and lack typical suprasubduction zone components (such as IAT and boninite). Thus, they probably formed in intracontinental ocean basins.