琼东南盆地新生代伸展过程及其区域性差异定量研究

Quantitative study on Cenozoic extension process and regional differences in Qiongdongnan Basin

以琼东南盆地为研究对象,自西向东选取了能控制盆地构造格局的7条骨干大剖面,应用Move软件中的2D模块分别对这7条骨干大剖面进行平衡剖面恢复,并计算了各剖面不同时期的伸展量、伸展率和伸展速率,在此基础上对琼东南盆地的构造演化过程及其区域性差异进行定量研究。研究表明:琼东南盆地自新生代以来处于一个持续伸展的过程,在36~28.4 Ma期间(崖城组沉积期)出现一个伸展高峰期,在36~23 Ma期间(渐新世)伸展速率达到最大值,说明渐新世断层活动最强烈,为盆地的主要伸展阶段;从23 Ma至今整体来说伸展率和伸展速率呈现逐渐减小的趋势,盆地伸展逐渐减弱。

Taking Qiongdongnan Basin as the research object,7 key sections that can control the basin’s tectonic pattern are selected from west to east to restore the balanced profile by using 2D Module of Move software.The extension distances,extension rates and extension velocities of these 7 sections in different periods are calculated.On this basis,the tectonic evolution process and its regional differences in the Qiongdongnan Basin are quantitatively studied.The results show that:(1)the Qiongdongnan Basin has been in a continuous extension process since Cenozoic,and an extension peak appeared during 36 to 28.4 Ma(deposition period of Yacheng Formation),and the extension rate reached the highest value during 36 to 23 Ma(Oligocene),which indicates that the fault activity is the most intense in Oligocene,and Oligocene is the main extension period of the basin;(2)from 23 Ma to the present,the extension rate and extension velocity have shown a gradual decreasing trend,and the extension of the basin has gradually weakened.