东海TB线剖面构造模拟研究

本文解释了横穿钱塘凹陷、西湖凹陷直至钓鱼岛隆褶带长约147km的TB地震剖面;针对东海陆架盆地自古新世以来经历了断陷一被动大陆边缘一挤压一拗陷多时期构造相叠加的特点,建立了拗陷模型、剖面平衡模型和断陷模型。利用作者开发的模拟软件包,计算恢复了各时期的地层原始厚度,再现了拗陷的沉降压实过程;由等面积和关键层平衡结合的方法,实现了T40-T20间挤压构造的复原,得到了平衡剖面并计算了各层面的缩短量;根据生长断裂信息反演犁式断裂在深部延伸的情况并计算了在拉张过程中上盘的位移场和运动轨迹;得到古新世时期从西湖凹陷至钓鱼岛隆褶带的拉张量约为10.4km。通过串接组合拗陷模型、剖面平衡模型和断陷模型,实现了断一挤一拗转化叠加的模拟,再现整个构造沉降发展史,并以一定时间间隔的图形形式表达了模拟的动态结果。

MODELLING STUDY ON THE PROFILE STRUCTURE OF TB LINE IN DONGHAI

In this paper, 147km of TB seismic profile across Qiantang Depression,Xihu Depression till Diaoyudao upfolded belt is interpreted. In view of the characteristics that Donghai continental shelf basin has gone through fault depression-passive continental margin-compression-depression multistages tectonic superimposition since the Paleocene,the models of depression,prOfile equilibrium and fault depression are established. By means of the modelling software package developed by the authors,the original thickness of eachstage strata is calculated and restored,and the subsiding and compacting processes of depression are reproduced. By the method of the combination of equiarea and critial-layer equilibrium,the recOvery of compressive structure between T40 and T20 is realized,equilibrium profile is obtained,and shorten range of each bedded plane is caIculated. Based on the situation that growth faulting information inverses plow faulting till in the deep part and by calculation on the displacement fields and movement loci of middle and upper plates during the course of extension,the extended range about 10.4km from Xihu Depression to Diaoyudao upfolded belt in the Paleocene period is obtained-By the connexion and combination Of depressiOn,profile equilibrium and fault depression models,the modelling of fault depression-compression-depressio inversion and superimposition is realized, the subducting and developing history of entire tectonics reappears,and the dynamic results of the modellings are shown by the graphs of certain time intervals.