二迭纪时,扬子区是相对稳定的地块。区内除两个长期隆起的古陆,即康滇、江南(确切地说是武陵、雪峰、九岭等一系列岛屿)古陆外,基本上是个陆表海,为特提斯海的一部分。沉积物以海相稳定组合类型为主,但在其东部和东南部的边缘,却发育一套与江南区十分类似的沉积物。由于两者之间呈渐变的关系,故本区的南界、东南界不易确定。本文考虑到栖霞期以后,特别是茅口、吴家坪期时,两者在岩相和生物相上的明显差异,将本区的南界与东南界置于芒街、钦州、柳州一线,沿江南古陆的南缘、东缘折向北至彭泽、黄梅一线。其北界和西界则与传统的界线一致。 During the Second Triassic, the Yangtze area was relatively stable. In addition to the two long-standing uplift of the ancient continent, namely Kang Dian, Jiangnan (specifically Wuling, Xuefeng, Jiuling and a series of islands) ancient land, is basically a surface sea, as part of the Tethys. Sediments are dominated by marine stable assemblages, but at the margins of the eastern and southeastern parts of the sediments there is a set of sediments very similar to the Gangnam area. As a gradual relationship between the two, so the area of ​​South, Southeast is not easy to determine. Considering the obvious differences between lithofacies and biofacies after the Qixia period, especially during the Maokou and Wujiaping periods, the southern boundary and the southeast boundary of this area are located in the first line of Mangjie, Qinzhou and Liuzhou, The southern edge of the ancient land, the eastern edge of the North to Pengze, Huang Mei line. Its northern and western boundaries are consistent with the traditional boundaries.