| Situated in Riduo Town,Maizhokungga County of Tibet,the Nongruri gold deposit is a typical epithermal Au-Sb deposit initially discovered and evaluated in eastern Gangdese metallogenic belt. It is tectonically located in the eastern segment of the Gangdese tectonic-magmatic zone of the Gangdese-Himalaya Tectonic Domain in the northern fringe of Gondwana. So far it has been 20 years since Nongruri gold deposit was discovered with the deepening of prospecting exploration degree,it has become a medium-scale deposit which contains more than 12 tons of Au metal reserves.Researchers have done lots of study on Nongruri gold deposit such as character of ore deposit geology, characteristics of wall rock alteration and metallogenic mechanism, the characteristics of fluid inclusions and metallogenic evolution metallogenic epoch and the ore mineral composition. However study of primary halos and its application on prospecting has not been launched yet. As no certain conclusion about erosion degree of the ore or whether there exists a blind ore has been proposed up to now so we choose No.23 exploration line profile which controls main ore-body the most has relatively more drilling holes and well preserved to do research on primary halos. Combine with mineral alteration and association characteristics on profile of No.23 exploration line, synthesis macro and micro geological information analysis the relationship between mineral zoning element zoning and mineralization, then we can estimate the possibility of mineralization on deep and edge.Mathematical statistics of Au, Ag, Cu, Pb, Zn, As, Sb, Bi, Hg, Co and Ni indicate that Au is major ore-forming element which is highly positively correlated with Hg, Ag, As and Sb, weakly positively correlated with Cu, and no obvious correlativity with other elements. With the addition of result of factor analysis and cluster analysis, main indicator elements of primary halos exploration in No.23 exploration line profile of Nongruri gold deposit are Hg, Ag, As and Sb, and the secondary indicator elements are Bi, Cu, Co and Ni; and homology of Au between Hg, Ag, As and Sb is good, so the possibility of them being from one same resource is high.Zoning of primary halos concentration manifests that Au、Ag and As have bigger anomaly area and intensity,Hg takes second place. What is more,the anomaly location of Au highly coincides with that of Ag,As and Hg,and they all have external,middle and inner zone geochemical anomalies. Sb、Bi and Co have tiny anomaly and Ni、Cu、Zn and Pb have no significant anomalies.The axial zoning sequence of No.23 exploration line profile,from top to bottom,is Co-Ni-Bi-Cu-Au-As-Sb-Hg-Ag-Zn-Pb,which expresses significant characteristics of zonation of opposite direction,indicating greatly extending of ore-body or high probability of blind gold ore-body existence.Study of zoning of mineral alteration indicate that silication,pyritization,sericitization,clayzation,carbonatization,realgarization and stibnitization are major alteration related to gold mineralization,of which,silication,pyritization and sericitization occur widely across the whole No.23 exploration line profile. Pyritization is generally intense but weak at some part. Carbonatization occurs moderately across the whole profile. Clayzation mainly in acid rocks. Realgarization and stibnitization are both weak across the whole rofile,developing at local area and the locations are accordant.Deep prospecting which combined with geochemical characteristics of primary halos and features of mineral alteration indicates that the great extending of controlled ore-bodies to the NW-trending and the big possibility of uncontrolled concealed ore-body. Silication,pyritization and sericitization are good directing marks for determine the range of mineralization and clayzation,carbonatization,realgarization and stibnitization can be used as a direct prospecting symbol for estimating the location of ore-body. |
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