扬子区晚二叠世—中三叠世海平面变化

Late Permian-Middle Triassic Sea Level Changes of Yangtze Platform

本文首先介绍了建立扬子地台晚二叠世—中三叠世海平面变化曲线的步骤,即将由生境型得出的水深曲线按阶转换为海平面变化曲线,然后将扬子区曲线与世界曲线进行了比较.结果表明,晚二叠世至Griesbachian期,由于世界上绝大部分地区缺上二叠统海相地层序列,扬子区曲线的这一部分可作为修改世界曲线的重要参考.扬子区早—中三叠世短期变化曲线与世界曲线一致,而长期曲线则不相符.扬子区的长期曲线对受印支运动影响的东亚区有代表性.扬子区的三级旋回与Haq等的世界曲线仅部分相符,但相符的部分其具体界线也不一致.这说明海平面变化在全球并不严格等时,一、二级旋回可能是世界性的,三级旋回则不是.

This paper first introduces procedures leading to establishment of Late Permian- Middle Triassic sea level change curve of Yangtze Platform. Bathymetric curves extracted from curve of habitat types are first transformed to sea level curves in the order of stages. The comparison between curves of Yangtze and the world reveals that since the Late Permian marine sequences are lacking in most parts of the world, the Late Permian to Griesbachian curve of Yangtze's curve may serve as an important parameter for further revision of the world curve. The Early- Middle Triassic short- term changes of Yangtze are briefly concordant with those of Haq's world curve, whereas its long-term changes are discordant. The latter, however, is representative of the East Asian regions affected by the Indosinian Orogeny. Basically the third cycles of Yangtze and the world are only partly concordant, and even in concordant cases their detailed boundaries are not coincident. This indicates that sea level changes are not strictly synchronous over the world. It seems that the 1st and 2nd cycles (supercycles and megacycles) may be world-wide, but not the 3rd cycles.