盆地金属矿穿透性地球化学勘查模型与案例  

Models and case history studies of deep-penetrating geochemical exploration for concealed deposits in basins

作　　者：张必敏[1,2,3] 王学求[1,2,3] 徐善法[1,2,3] 姚文生[1,2,3] 叶荣[4] ZHANG Bi-min WANG Xue-qiu XU Shan-fa YAOWen-sheng YE Rong(Institute of Geophysical and Geochemical Exploration, CAGS, Langfang 065000, Hebei, China Key Laboratory ofGeochemical Exploration, Ministry of Land and Resources, Langfang 065000, Hebei, China UNESCO International Center onGlobal-scale Geochemistry, Langfang 065000, Hebei, China China University of Geosciences, Beijing 100083, China)

机构地区：[1]国土资源部地球化学探测技术重点实验室,河北廊坊065000 [2]中国地质科学院地球物理地球化学勘查研究所,河北廊坊065000 [3]联合国教科文组织全球尺度地球化学国际研究中心,河北廊坊065000 [4]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《中国地质》2016年第5期1697-1709,共13页Geology in China

基　　金：国土资源部公益性行业科研专项(深部探测专项Sino Probe-04;201511034);国家自然科学基金项目(41573044);中国地质调查局地质调查项目(12120113100900);国家重点研发计划项目(2016YFC0600600)联合资助~~

摘　　要：近20年来,越来越多的大型金属矿床在盆地内部及其边缘被发现。传统的勘查地球化学方法对盆地及盆山边缘覆盖区无能为力,深穿透地球化学探测技术为解决盆地及其边缘覆盖区找矿难题提供了一种行之有效的手段。文章通过对沉积砂岩盆地铀矿、火山岩盆地银多金属矿、变质岩盖层铜镍矿和沉积盖层金矿开展探测试验,得出:(1)砂岩型铀矿中活动性铀主要以铀酰络阳离子的形式存在,铀酰络阳离子很容易受地下水运动及蒸发蒸腾作用而发生迁移,迁移通道包括砂岩的孔隙、构造裂隙等,到达地表后,铀酰络阳离子易与土壤中带负电的黏土矿物结合而赋存其中,使用微细粒分离和活动态提取两种方法均能圈定矿致异常;(2)火山岩盆地中,与火山岩近乎同期形成的矿床,矿床形成过程中含矿流体携带成矿元素银、金、铜等沿构造裂隙运移,迁移到地表后被土壤中的黏土矿物所吸附,使用土壤活动态测量和微细粒分离测量均能有效圈定已知矿体,异常直接位于矿体上方;(3)变质岩盆地超基性岩体在侵位过程中,岩体与变质岩接触带将产生大量的构造裂隙,因此当流体通过岩体与围岩接触带时,将携带矿体中铜、镍向上迁移至地表,形成环状异常;(4)洛宁盆地金矿成矿过程中,成矿元素金、银等以络合物、纳米级单质或合金等形式通过流体携带顺着构造破碎带向上迁移,地表岩石风化发生成矿元素解离,后期被黄土覆盖,矿体或岩石解离的化合物或纳米颗粒可以穿过黄土孔隙向上迁移至地表,并赋存于表层黄土的细粒级黏土中,因此采用土壤微细粒分离测量可圈出矿致异常。本文根据深穿透地球化学方法应用效果,异常的形态,并结合盖层的特点,成矿元素的存在形式、迁移方式以及在地表的赋存状态,初步建立了盆地金属矿深穿透地球化学勘查模型,为盆地盖层区地球化学�In the past twenty years, more and more mineral deposits were discovered in basins. The traditional geochemicalexploration methods are not effective in mineral exploration of concealed deposits in basins. Deep- penetrating geochemistryprovides a new approach for exploration in basins. The case history studies from the concealed sandstone- type uranium deposithosted in a sedimentary basin, the concealed Ag-polymetallic deposit in a volcanic basin, the concealed Cu-Ni deposit in a basincovered by metamorphic rocks and the concealed Au deposit covered by loess have led the authors to reach the followingconclusions： （1） Uranium is converted to uranyl ions [UO2]2＋ under the oxidizing condition and is easy to migrate under the influenceof groundwater movement along sandstone pore structure and tectonic fissures; the uranyl ions are absorbed on clay minerals aftermigrattion to earth’s surface, because clay layers have a net negative charge, which needs to be balanced by interlayer cations;leaching of mobile forms of elements in soils and separation of fine-grained soils can be used to determine the orebodies; （2） TheYueyang Ag-polymetallic deposit was nearly formed in the same period as the volcanic rock; Ore-bearing fluid migrated to earth’ssurface along tectonic fissures in the formation process of the deposit; mobile forms of metals in ore-bearing fluid were absorbed onclay minerals; leaching of mobile forms of elements in soils and separation of fine- grained soils can be used to determine theorebodies in volcanic basins; anomalies of elements are directly displayed over the blind orebodies; （3） the contact zone betweenintrusive mass and metamorphic rock generated a lot of tectonic fissures in the process of emplacement of the ultrabasic intrusion;and the fluid would take ore-forming elements Cu and Ni and migrate to earth’s surface and form cyclic anomaly; （4） ore-formingelements Au and Ag in the form of complexes, nano-scale elemental or alloy particles taken by fluid migrated upward in t

关 键 词：盆地 盖层 隐伏矿 深穿透地球化学 纳米晶体 迁移模型 

分 类 号：P632[天文地球—地质矿产勘探] P618.2[天文地球—地质学]