The second step is to read the contents of the map frame. Before analyzing the details of the map, let's read through the contents of the geological map. When reading through, firstly, according to the distribution of topographic contours, water system and elevation points, we can understand the topographic features, the main direction of mountain water system distribution, the relationship between topography and lithology and structure, and then compare the legends to understand the distribution and occurrence of strata in each period, the distribution direction of main folds and fault structures, the distribution and occurrence of magmatic rocks, etc. , and find out the general geological structure outline of this area. On this basis, the strata, folds, faults, magmatic rocks, metamorphic rocks, minerals and other details can be analyzed in detail step by step.
The third step, comprehensive induction, puts forward that the geological structure in the problem geological map is not an isolated thing. These geological phenomena are the result of the historical evolution and development of this area, and are essentially the result of various geological processes experienced in this area. Therefore, they are closely related. After analyzing the geological phenomena one by one. We should further find out the internal relations between these geological phenomena. Analyze how they evolved into what we see now, that is, synthesize the geological development of this area. Finally, ask questions.
Extended data
Most geological maps show the occurrence factors and fault types of faults with certain symbols; Fault lines are also drawn on geological maps, and there are no symbols indicating the occurrence and type of faults. At this point, we should first pay attention to the general dip and dip angle of the fault, and then judge the relative displacement direction of the two plates. Regarding the existence of faults, we can also test them without fault symbols.
When a stratigraphic boundary suddenly breaks along the strike on the geological map, it means that there are oblique faults or oblique faults there. If it is found on the map that the strata are abnormally missing along the dip angle (which can be identified by comparing the stratigraphic histogram) or appear asymmetrically repeatedly, strike faults often exist.
When explaining the above folds and faults, it is beneficial to refer to the attached geological profile, but this approach should focus on the interpretation according to the geological map.