龙门山碧口断块的形成及其空间归位研究

Formation of the Bikou fault block in the Longmen Mountains and restoration of its original spatial position

按照地质异常的分析指导思想,本文提出地质异常体空间归位概念,对龙门山北端的碧口断块进行了空间归位分析。文中对碧口断块的运动轨迹进行了复原分析,认为本区地质空间异常体是受青藏高原、华南陆块和华北陆块三重构造运动作用的结果。由于它们各自的构造运动方向不同,造成其在不同时间、不同空间位置所起的作用也不相同。笔者将碧口断块运动的主要过程划分为4个阶段:①挤压断裂作用;②西向滑脱作用;③右旋扭转作用;④东向重力挤压作用,这样就解释了本区的地质构造成因。因此在研究该区或者其他复杂地区的地质问题时,要考虑多个作用主体以及在不同时间的影响作用,从时间、空间的动态演变过程来加以认识分析地质体的成因。由于不同构造主体在不同时间的作用,同时也造成了异常地质体在空间分布上的多样性,因此,本文提出的异常地质体空间归位概念,对认识成矿多样性以及成矿谱系研究具有重大的现实意义。

In light of the guiding through for the analysis of geologic a nomalies,this paper puts forward the concept of restoration of original spat ial positions of anomalous geologic bodies and studies the restora-tion of the original spatial positions of the Bikou fault block at the northern end of the Longmen Moun-tains.The trajectory of the motion of the Bikou fault blo ck is restored.It is believed that the spatial geo-logic anomalous body in th e area is the result of three-fold tectonic movements of the Qinghai-Tibet, South China block,and North China block.The different directions of their t ectonic movements resulted in their different effects exerted in different tim es and spatial positions.The authors divide the main process of motion of the Bikou fault block into four stages:(1)compressional faulting,(2)west- directed decollement ,(3)dextral shear,and(4)east-directed gravitationa l compression.This interprets the tectonic origin of the area.Therefore,in t he study of the geological problems in the area or other complex area,it is necessary to consider the main parts of several effects and their influences in different times and under-stand and analyze the origin of a geologic body in the context of dynamic evolu tion in time and space.Effects of different tectonic main parts in different times also give rise to the diversity of anom alous geo-logic bodies in spatial distribution.Therefore,this paper advances the concept of restoration of original spa-tial positions of anomalous g eologic bodies,which has great realistic significance for the understanding of the diversity of mineralization and study of hierarchy of mineralization.