裂谷地层的气候和构造控制:Zscape模型分析与在松辽盆地北安断陷的应用

Climate and Tectonic Controls on the Rift Stratigraphy:Analysis of Zscape Model and its Application in the Beian Faulting Depression of the Songliao Basin

气候和构造是裂谷盆地地层形成的两个重要控制因素。Zscape数字陆地景观演化模型通过对裂谷盆地汇水扇体系的模拟揭示出一些与裂谷盆地地层形成相关的气候及构造过程。Zscape模型的相关实验结果与层序地层结构的分析认为:(1)扇面积与断层滑动速率成反比;(2)高水位期大量沉积物进积是断层滑动速率减小所引发的;(3)层序界面的形成与低水位和水进沉积是降水速率变化所致。这些认识用于分析北安断陷沙河子期大量扇体沉积的发育和层序结构的形成。沙河子组下部层序发育时期构造活动剧烈,上部层序发育时期构造活动相对趋于稳定,断裂活动和降水速率的变化控制了层序发育。Zscape模型及其实验结果的地质分析,以及在北安断陷的应用显示,构造和气候的单因素分析对一些地质认识,特别是沉积作用对于断裂活动的滞后性的理论解释起到了推动作用。

Climate and tectonics are the two key controls for the formation of the stratigraphy of a rift basin. Zscape numerical landscape evolution model reveals some climate and tectonic processes about the formation of the stratigraphy by the simulation to catchment-fan system of the rift basin. Some views from the analyses of sequence stratigraphic architecture and the relevant experiments results of Zscape model are： （1） there are an inverse relationship between the fan area and the fault slip rate; （2） the progradation of a large amount of sediments during highstand is result from the decreased fault slip rate,and （3） the formation of the sequence boundary and the sedimentation during the lowstand and the transgressive are the results from of the changes of precipitation rates. These views are used in analyzing the development of the fans of the Shahezi Formation in the Beian faulting depression and the formation of the sequence architecture. The tectonic activity was violent during the development of the lower sequence of the Shahezi, and it turned to be relatively stable during development of the upper sequence. The faulting and the changes of precipitation rates controlled the development of the sequences of the Shahezi Formation. The Zscape model and the geological analysis of its experimental results, as well as its application in the Beian faulting depression, demonstrate the significances for some geological understandings by analysis of tectonic and climate factors, especially in the theoretical interpretation of deposition lagging to faulting.