CUI Jun-hao¹, REN Tao², HU Yu-zhao², HUANG Jian-guo², WANG Lei², YANG Jing-kui², SU Jie²

(1. City College, Kunming University of Science and Technology, Kunming 650051, China;
2. Faculty of Land and Resource Engineering, Kunming University of Science and Technology, South-West Institute of Geological Survey, Gelolgical Survey Centre for Nonferrous Metals Resources, Kunming 650093, China)

Abstract: Shigu group, located in Northwestern Yunnan Province, China, is a part of the Late Proterozoic Shigu-Diancangshan-Ailaoshan metamorphic rocks belt. The belt is considered as the Yangtze plate base. The upper Shigu group is metamorphic rock, mainly consists of sericite, quartz, chlorite, and a small amount of albite and ilmenite. The metamorphic rock shows blastic texture. In SiO₂-TiO₂ diagrams, Badi metamorphic rocks fall into the field of igneous and sedimentary boundaries, showing both characteristics. All of Shaw's DF values are lower than 0, indicating negative metamorphic rocks. The rocks have high Al₂O₃ and K₂O contents; these features show that the schist contains clay and K-bearing minerals. The major elements tectonic setting discrimination diagrams show that the rocks have formed in the environment of active continental margin and oceanic island arcs. Integrated regional geology, petrology and major element analysis indicate that the schist is the felsic clastic and claystone rock.

Key words: Shigu group; Late Proterozoic; rock recovery; Badi; Northwest Yunnan