拉伸构造区古地质构造恢复和平衡剖面建立——以渤海湾盆地为例

THE REPRODUCTION OF PALEO-STRUCTURE AND THE ESTABLISH OF EQUILIBRIUM PROFILE FOR EXTENSION STRUCTURE AREA——An Example of Bohai Gulf Basin

刘池洋

Liu Chiyang

西北大学地质系

Geological Department of Northwest University

渤海湾盆地剥蚀改造强烈,它改变着断块的几何形态、岩石体积和地层分布。此外,盆地在新生代拉张的同时,伴有剪切变形,这使垂直于构造线的剖面的岩石总面积,在变形前后发生变化。这两种因素直接影响着古地质构造恢复的质量。本文以渤海湾盆地为例,根据拉伸构造区的地质特点,提出以地质恢复为基础,地质恢复与几何作图相结合的研究方法。此法将非刚性翘倾断块作为主要研究对象,通过恢复已被剥蚀的岩石,消除后期构造变动的改造,重塑各断块的初始形态,然后从断块→剖面→平面和空间→时间逐步恢复古地质构造,再现拉伸构造区古地质构造面貌,求取拉伸量,建立高质量的平衡剖面。

The severe denudaticn and reworks in Bohai Gulf Basin changed the geometric configuration, the rock volume, and the formation distribution of fault blocks.In addition, the occurrence of Cenozoic extension associated with shearing deformation in the basin changed the total rock area of the profile which meets the structure line at right angle. The two factors mentioned above would directly influence the quality of paleo-structure reproduction. Taking Bohai Gulf Basin as an example, the author of this paper suggested the analysis on geological reproduction combined with geometric mapping based on geological characters of extension-structure regions. Such a kind of analysis would take non-rigid tilting fault blocks as subjects and reconstruct the initial configurations of various fault blocks by reproducing the denuded rock volume without subsequent reworks of structural deformation. Thereafter, the paleo-structures would be progres-sively reprepoduced following the sequence of fault block, longitudinal section, cross-section, space and timing. Thus, the reproduction of Paleo-structural configuration in the structural extension regions Can be made, the amount of extension is quantified and the equilibrium profile can be established with good quality.

https://doi.org/10.11781/sysydz198801033