Tracing The Sources Of Metals In Geogas From Metal Deposits By Pb Isotopes, Trace Elements And REE

Exploration activity is returning to areas covered by variety ofoverburdens like loess and alluvium as most mineral deposits in outcroparea were found. It is urgent to seek a new technique to be appliable formineral exploration in the covered areas.Geogas survey,found by K.Kristiansson and L.Malmqvist in 1980's, isa potential mean for geochemical explotion in covered regions and has beenstudied since it was introduced into China. A lot of improvement has beenmade in China as not stopping efforts by many chinesegeochemists,especially by using liquid collectors.However, little knowledge about it formation and lack of standardprocedures greatly limited its use in practical mineral exploration. Itis necessory to do some research on the formation mechanism of geogas,especially tracing the sources of metals in geogas.After systematically analysing elements and Pb isotopes in deferentmedia including rock, loess, ore and geogas from the known deposits, theauthor concludes:The blank of collectors was significantly lowed by purifying thesolvent and controlling the operation environment and the capacity tocatch metals for geogas collectors and reproductivity of geogasobservation were greatly improved by changing the sampling device and testlayout.The ratios of Pb isotopes in geogas were first determined byisotope-dilution ICP/MS technique in the world. In comparison with Pbisotopes in the rock, ore, loess and red soil layer, Pb in geogas mostlycomes from the below Pb-Zn ore bodies and indicates the geogas metals mightmigrate from deep ore deposits.The charateristics of REE and trace elements can be used to trace thesourses of geogas. The improved geogas observation technique was used asthe main tool in practical mineral exploration for chromite, Nickel andpolymetallic deposits in Qinghai and Gansu. A polymetallic and goldmineralization was discovered in covered area (80 overburdencover),Qilian Basin, Qinghai by geogas survey. The above results show thatgeogas anomalies of metal elements are related to the deep orebodies andcan indicate the mineralizations in overburden area. It can be concludedthat geogas survey will play an important role in mineral exploration incovered area.