Problems and mapping method in mapping pre-Sinian low-grade metamorphic terrains of South China

Abstract: Pre-Sinian low-grade metamorphic rocks in South China are a special rock type, which is different from not only medium-and high-grade metamorphic rocks but also sedimentary rocks. Because of its particularity and lacking of a mapping method specially for them, there are a number of prominent problems in displaying the available results of regional survey, e. g. there is much difference between the presentation of the map and words and the temporal-spatial distribution of geologic bodies. Through an analysis of major problems and practice and checking of several related projects, the authors have preliminarily summed up a mapping method, i. e. proceeding from an analysis of an area, first establish a lithologic maker bed and structural style of the area, and then take the marker bed and structural style as the core and extrapolate and extend them to other areas; on the basis of gaining knowledge and checking the results repeatedly, establish mapping units and perfect and finalize the structural style and structure of the map surface