中扬子区中二叠统层序地层研究

THE MIDDLE PERMIAN SEQUENCE STRATIGRAPHY OF THE MID-YANGTZE AREA

研究了中扬子区中二叠统层序界面和体系域特点,分析了层序样式的基本类型及其特征,建立了中扬子区层序地层格架,共划分出1个二级层序、6个三级层序(PSQ2—PSQ7),平均延时约1.7myr。海侵体系域为向岸退积的复合体,颜色普遍较深;高位体系域为向海进积的复合体,颜色相对较浅。总体上以H型样式为主,T型样式和TH型样式数量相当,反映中二叠世快速海侵缓慢海退的沉积特点,并且海侵海退幅度不大,水体中等。二级层序体系域和三级层序体系域南北向差异性不明显。

A systematic study has been made on the Middle Permian sequence stratigraphy of the Mid-Yangtze area, the sequence framework has been established,the characters of system tract and sequence boundaries have been researched,and the basic kinds of sequence style and their features have been analysed.As a result,there is one 2-order sequence and six 3-order sequences (PSQ2—PSQ7),and the average age of the sequences is about 1.7myr. The coloration of the rock in the trandsgressive system tract is dark in general, and the deposit is a complex retrograding to coast.The coloration of the rocks in the high system tract is light in general,and the deposit is a complex prograding to sea.The main sequence style is H style, and T and TH styles are equal in content.The character shows that transgression is rapid,regression is slow,and the range ability is not large,the water mass may be midium in the Middle Permian. The 2-order and 3-order sequences in the north are not distinctly different from those in the south.