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.