THE ENRICHMENT AND GENESIS OF PLACER GOLD IN SHAANXI-GANSU SICHUAN BORDER “GOLD TRIANGLE” REGION

The studying area lies between 104°00'E to 106°45'E and 32°00'N to 33°40'N. The stratigraphy ranges from Bikou group of pre -Sinian system to Quaternary system,of which Bikou group and Silurian Maoxian group are broadly distributed with bigh Aubackground. Magmatic rocks are developed. Quaternary may be subdivided into 4 units. The placer gold is contained mainly in Holocene alluvium. The neotectonism in this area is typified with intermittent raising and vertical viberating,which has made a favourable condition for the forming of Holocene alluvial gold deposits.