Geological Characteristics and Enrichment Laws of Tianjiahe Placer Gold Deposit in Lixian County, Gansu Province

This paper mainly expounds the geological characteristics, Quaternary geology, geomorphic conditions and metallogenic characteristics of the Tianjiahe placer gold deposits in Lixian County, Gansu Province, analyzes the genesis and distribution characteristics of various types of loose deposits, and summarizes the enrichment laws and metallogenic characteristics of placer gold. Through the determination of gravel content, gravel degree and mud content of mixed sand, the variation characteristics of the thickness and grade of ore body in Longitudinal and vertical directions are analyzed. This paper finds out the source of ore-forming materials, the enrichment location, the supplying direction and transporting distance,etc. Tianjiahe placer gold deposit developed in the Quaternary Holocene riverbed and flood plain facies. it is river alluvial type, and riverbed and flood plain type as well. The metallogenic epoch is quaternary Holocene.In the Holocene, the crust rose slowly, while the lateral erosion of the river enhanced. All gold-bearing geologic bodies and terraces were transported and sorted, thus formed the Tijiahe placer gold deposit at the bottom of the valley. The discovery and evaluation provide prospecting criteria and a prospecting model for similar type of placer gold deposits in this area.