1∶2.5万地球化学测量在东昆仑巴隆地区找矿中的应用

An Application of 1∶25000 Geochemical Survey to Ore Prospecting in Balong Area of East Kunlun

青海省东昆仑巴隆地区位于柴达木盆地东南缘、东昆仑造山带中部,由于其特殊的自然地理景观,北部水系不发育,风成物干扰较严重;南部高山区碎石流发育,影响水系沉积物汇聚,对该区的地质找矿工作影响严重。通过开展1∶2.5万地球化学测量,确定最低采样密度为16个点/km2,采样介质以水系沉积物为主、残坡积碎屑物质为辅,采样粒度为-2~0.3mm(-10~60目)筛内样。通过元素含量、富集离散特征、组合特征及元素的空间分布特征分析,确定工作区内主要成矿元素为Au、La、Y。Au富集成矿与昆北构造分区中中三叠世花岗闪长岩和昆南构造分区中金水口群地层有关;稀土元素La、Y富集成矿主要与工作区南部的碱性岩体(正长花岗岩)有关。在工作区南部高寒山区碎石流发育地带圈定出GA59新的异常,并有一定的找矿突破。在工作区北部水系不发育、风成砂、风成黄土干扰区圈定了金异常并成功发现金铅矿体。表明1∶2.5万地球化学测量方法有效,对东昆仑的地质找矿工作具有指导作用。

Balong area of East Kunlun in Qinghai province is located in the southeast edge of Qaidam basin,central Kunlun orogenic belt.Due to its special natural and geographical landscapes,the northern water system is not developed and the wind deposit is seriously disturbed.The development of debris flow in the southern mountain area affects the convergence of stream sediments,which seriously affects the geological prospecting work in this area.Based on the 1 ∶25 000 geochemical survey,the minimum sampling density is 16 points/km 2,and the sampling medium is mainly composed of stream sediments and residual debris.The sampling size is -2~0.3 mm (-10~60) mesh.In the analysis of element content,we have known about enrichment and dispersion characteristics,combination characteristics and spatial distribution characteristics of elements.It is determined that the main metallogenic elements in the work area are Au、La and Y.Au mineralization and tectonic zoning is related to granodiorite of the middle Triassic in north Kunlun tectonic division and the Jinshuikou stratum in south Kunlun tectonic division.The enrichment and mineralization of Mo and rare earth elements La、Y are mainly related to the alkaline rock mass (syenite) in the south of the working area.In the south of the working area,a new anomaly GA59 is delineated in the development zone of the rock debris flow in the high and cold mountains,and a certain breakthrough is made in the prospecting.The gold anomalies were delineated in the the northern part of the working area with undeveloped water system,which is disturbed by the aeolian sand and the aeolian loess,and the gold and lead orebodies were discovered successfully.The results show that the 1 ∶25 000 geochemical survey method is effective and has a guiding role in the geological prospecting work in East Kunlun area.