Penetrating Geochemical Exploration Applied To Mineral Exploration In Covered Areas And Its Mechanism

The discovery of economic ore deposits is increasingly dependent on the expression of ore-bearing signature under the overburden on the surface.Therefore,mineral exploration under covered areas have attracted many studies.In order to meet the challenge of geochemical exploration in the coverage area,penetrating geochemical exploration has been developed.At present,penetrating geochemical exploration techniques such as fine-grained soil digestion,mobile forms of metals in soil,geogas prospecting,geoelectrochemical measurement and vegetation survey are formed.However,the mechanism of penetrating geochemical anomaly needs to be further explored.Therefore,this paper selects Shenjiaya gold deposit in the loesscovered area,the Nuheting uranium deposit in the arid and semi-arid grassland area and three different types of deposits in the Zijinshan ore field for the research of the mineralogy,metallogenic element occurrence and penetrating geochemical exploration.Geogas prospecting has shown that there is geochemical information in the geogas,which can reflect the deep mineralization.The spatial distribution pattern of elements in the geogas can indicate deep ore bodies,strongly altered rocks and faults,and the composition of the geogas corresponds to the composition of the ores.Geogas prospecting can be used for the exploration of hidden gold deposits in the loess-covered area.The treated polyurethane foam is a suitable capture carrier for geogas.Transported sediments of the Nuheting uranium deposit in the Erlian Basin suffered from moderate weathering.The statistic features of trace elements and isotopes of soils indicate that Pb isotopic composition of soils is affected by the concealed uranium deposit.In the Pb isotope composition diagram,the Pb isotope composition of the soil over or near the deposit is closer to those of the ores compared with the distal soil.The property of the high Pb isotopic content in the deep ore is inherited by the soil over the ore,indicating the source of penetrating geochemical anomalies in the soil comes from buried deposit.Nanoparticles in soil and geogas are widely existed,and both of them are one of the forms of penetrating geochemical anomalies.Submicroscopic or nanoscale gold and silver are also present in the hydrothermal ore.The nanoparticles separated from ore,soil and geogas are similar in shape.The single nanoparticle is mainly spherical and ellipsoidal.The interior of nanoparticles has lattice structure and they often form aggregates.The nanoparticle composition has significant differences in different deposits.The Cu-Au combination can indicate gold deposits,and MoRe can indicate sandstone-type uranium deposits,and the nanoparticle composition is obviously controlled by deep mineralization.The composition and structure of the nanoparticles in the ore-soil-geogas chain show the same origin.It is believed that the nanoparticles in the surficial environment can reflect deep mineralization,which is the active form of mineralized and associated elements on the surface.The nature of the mobilization and passing through geological process of nanoparticles is an intrinsic reason for penetrating geochemical exploration to identify deep deposits in the coverage area.