Shenzha-Bange Regional Geochemical Anomalies And Ore Prospecting Evaluation In Tibet

Shenzha-Bange area is located in the plateau lake basin area In central Tibet, ishigher in sousth than in north in elevation, in sousth the area is Adjacent to theGangdisi southwest mountain and cross the Nianqing-Tanggula mountain southeast,in north the area is Adjacent to Selingcuo, Tibet’s second largest lake,terrain isrelatively flat. Research area crosses northern middle of the Gangdisi metallogenicbelt, and southern middle of Bangonghu-Nujiang metallogenic belt, is rich in mineralresources. Research area in this papers is located in Naqu area’s Central south andnorth of Dangxiong,Lasa, geographical range:88°~92°E,30°30’~31°30’N, spanningeight map sheet(1:250000).Stratum in the study area belongs to Yunnan-Tibet region’s Gangdisi-Tengchongstratigraphic area and Bangongcuo-Nujiang stratigraphic area.strata are widelydistributed in the study area, from the ordovician to the quaternary exposed to someextent. Magmatic activity is intense and frequent in the study area, the study areaexperiences varying degrees of magmatic activity since the late Triassic to Eocene.Magmatic activity is strongest especially in the cretaceous, the cretaceous is the mainperiod of magmatic activity in the area. Experiencing many times’ structure, magmaand hydrothermal geological process, research area’s geological background is verycomplex. It is such a complex geological background created advantageousmetallogenic conditions in the study area, the study area is very rich in mineralresources.The multivariate statistics of39elements in1:500000stream sediments data inthe study area indicates that As,Be,Bi,Li,Na,Si,Sn,andW’background value is higherthan the element background value in the stream sediments in China and the elementbackground value in high-cold mountainous districts in China; Ca’s background value is higher than that in stream sediment,but lower than that in high-cold mountainousdistricts. Cr’s background value is lower than that in stream sediment,but higher thanthat in high-cold mountainous districts,The remaining elements’background value isbelow the background value in the stream sediments and in high-cold mountainousdistricts in ChinaThe elements geochemical background and the known ore deposit relationshipshow that Cr mineralization is closely related to the background, the background ishiger, the mineralization is better;Fe, Cu, Ag mineralization is partly related tobackground, Au mineralization has little to do with background.“Sub area threshold line value filtering method” make background and anomalythreshold to be discontinuous surface, is a very good solution to data processingproblems in the complex geological background in the study area, this paper use themethod selected Ag, Au, Cu, Cr, Ni, Sn of the single element anomalies. Abnormal ofCr, Ni, have clear zoning, large range of lining values, and the deposit (point) matchdegree is high, All these above prove "sub area threshold line value filtering method"in the study area of ultrabasic rock metallogenic specificity of Cr, Ni elements effectis good. Contrast line value range small elements Cu, Au, Ag and Cu, due to therestrictions on migration of elements geochemical landscape, makes the backgroundand anomaly of larger scope overlap, the ability to recognize is restricted."Weak geochemical information processing technology" is used to extractAg-Pb-Zn-Cd, Au-Sn, Cu-Mo element combination anomaly, eliminates theinterference of the the geochemical landscape and background value, realizes theorganic separation between the background and anomaly, strengthens the anomaly,anomalies are greatly strengthened around anomalies extracted by "sub area thresholdline value filtering method" abnormal,anomalies are extracted in the area where "subarea threshold line value filtering method" can’t extract anomalies, The anomaly andthe known ore deposits’ corresponding is very good, is a very good indicator toprospect ore deposits (or points) of mineralization information weak and theconcealed ore deposits.Verification to5of the weak anomaly extracted by "Weak geochemicalinformation processing technology" confirmes that five anomaly is real, shows thatthis method applied in this research area has obtained the good effect, the weakanomaly ore-forming is true.According to the abnormal screening and classification,16prospecting prospect areas(A type:10, B type:6) in the study area are showed,which have a great prospecting potential.