编制盆地复原古构造图的若干问题的讨论

为了描述盆地三维构造的演化过程,通常需要编制不同地质时期的古构造等构造线图。编制古构造等高线图是一个复杂的研究过程,可能遇到许多概念性和技术性问题,但是所有问题都必须在地质平衡概念约束下寻求解决途径。本文讨论了按照地质平衡概念编制古构造等高线图的基本原则和可能的技术方案,包括研究构造变形模式、复原剥失厚度及其分布、复原断层位移、去压实校正等。运用地质平衡概念将较浅地层界面的构造等高线图复原到代表特定地质时期地形面的原始状态,相应地将较深地层界面的构造等高线图复原得的古构造等高线图。运用地质平衡概念编制的古构造等高线图比传统的只用地层残余厚度编制的古构造等高线图能更合理地反映地质时期的盆地古构造三维几何特征。

SOME PROBLEMS ABOUT COMPILING A RESTORED PALEO-STRUCTURAL MAP OF BASIN

In order to picture the evolution of 3 D structure in a basin, it was necessary to compile a series of paleo structural contour maps in varied epochs. The project of compiling paleo structural contour map was a complex research process, in which the researchers might meet various conceptual and technical problems, and whole the process should be restricted by concept of "balance in geology". This paper discussed some key problems, such as how to select a logical model of deformation, how to restore the denuded thickness and distribution, how to restore displacement of faults, how to do de compaction correction and so on. An acceptable method should be as follows: an upper structure contour map representing a definite geological epoch being restored to horizontal first, then to restore the geometry of the structural contour maps below the upper structure contour map according to geological epoch under restriction of "balance in geology". To compile a reasonable paleo structural contour map, it was necessary to have not only a series of high quality structural contour maps but also some important assistant maps and data, for example, profile sections of tectonic evolution, isopach map of erosion, table of de compaction correction and so on. The paleo structural contour map restored by concept of "balance in geology" might be more reasonable to depict the 3 D structural geometry in the geological epochs than the map compiled by utilizing the thickness of relict strata.