陕、甘、川“金三角”地区砂金富集规律及成因类型

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

摘要: 区内砂金矿大都分布在嘉陵江、涪江、白龙江和汉水的河床、河漫滩及Ⅰ级阶地内。在河道由开阔趋向狭窄或由狭窄突变为开阔地段、河流转弯的凸岸（堆积岸）弧形拐弯偏向上游地段、支沟与主河道文汇处靠下游等地段砂金相对富集。砂金主要富集在松散沉积层近底部的含泥砂砾层中。区内砂金矿的成因类型分为冲积型河床砂金矿、冲积型河漫滩砂金矿和冲积型阶地砂金矿三种。成矿时代为全新世早期。形成砂金矿必须具备两个条件：一是必须有砂金矿质来源，即必须有含金地质体的存在；二是有适宜的外营力作用、良好的地貌条件和有利的新构造运动，两者缺一不可。据此划出琵琶寺一河口和刘家坪-椒园里两个找矿远景区。

Abstract: 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.