Abstract: Abstract: A metamorphic belt is exposed in the central segment (Yongping-Yunlong) of the Lancangjiang fault. The major minerals of the metamorphic rocks in the belt are quartz, biotite and muscovite. The petrochemical composition suggests that the metamorphic rocks are aluminosilicates and the element geochemistry suggests that the protolith of this metamorphic series is chiefly sedimentary rocks but is likely to be introduced by volcanic tuffaceous material. This indicates that the volcanic belt exposed at the northern and southern ends of this metamorphic belt is discontinuous in this segment of the area. Therefore, attention should be paid to looking for metamorphosed sedimentary mineral deposits when carrying out mineral exploration in the area.