结构可控的地质解释——侵入岩专题地质填图构想

火成岩及其组合的性质不仅受岩浆系统本身性质的约束,也受到成岩环境的控制。因此,火成岩分布区的地质填图应当立足于结构可控的地质解释。基于这种认识,建议侵入岩专题填图按照岩浆系统的几何尺度及其与动力系统的关系划分填图单位。一级岩浆系统受控于全球动力学系统,具有最大的几何尺度;二级岩浆系统与区域地质历史有关,是全球动力系统与岩石圈系统相互作用的产物;三级岩浆系统受控于局部动力系统,与全球动力系统没有直接联系;四级岩浆系统受控于岩浆动力系统与围岩动力系统的相互作用,通常与岩浆产量和通道条件紧密联系在一起;五级岩浆系统受控于具体的岩浆过程,通常是侵入岩区的最小填图单位。但是,岩浆系统具有可无限细分的特点,填图过程中可根据具体情况进一步划分更次级的岩浆系统。对于几何尺度小于地质图表述能力的岩浆系统,建议制作局部放大的专题地质图件,以展示特定岩浆系统的地质特征。

The structure-controlled geological interpretations:A consideration for special mapping of intrusive rocks

The development of earth sciences and determining technologies calls for adopting new methods in regional geological mapping. Recently, it has been recognized that the magmatic system is complex, which implies that the features of igneous rocks and their assemblages are controlled not only by the magmatic system itself but also by the rock-forming environments. Therefore, the mapping of igneous rocks should be based on the structure-controlled geological interpretations. Accordingly, the authors propose that the mapping units division should be based on the relationship between geometric scale and dynamic system in special mapping of intrusive rocks. The first grade of magmatic system is controlled by the global dynamic system, and has the maximum scale. The second grade is related to the regional geological history, and results from the interaction between the global dynamic system and the regional lithosphere system. The third grade is controlled by the local dynamic systems such as lithosphere delimination, and is not related to the global dynamic system. The fourth grade is controlled by interaction between the magmatic system and wall rock dynamic system, which is commonly related to the magma production and the conduit conditions. The fifth grade may be the minimum mapping unit in the area of intrusive rocks, and its features are decided by the specific magmatic processes. However, the magmatic system can be divided infinitely. One may divide the system into more secondary magmatic systems according to the local situations in geological mapping. The authors hold that a special geological map should be compiled to show the geological characteristics of the special magmatic system if they are too small to be seen.