International Geologiical Congress - Oslo 2008

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MRD-02 Deep sources and signatures of ore forming systems - a tool for new discoveries of mineral deposits

 

Tectono-geochemistry ore-finding method for concealed ore-bodies as exemplified by the Zn-Pb-(Ag-Ge) metallogenic district in Northeast Yunnan, China

 

Runsheng Han, Kunming University of Science and Technology (China)
Haijun Zou, Kunming University of Science and Technology (China)
Bo Li, Kunming University of Science and Technology (China)
Yuzhao Hu, Kunming University of Science and Technology (China)
 

 

The typical high-grade Zn-Pb-(Ag-Ge) deposits (the Huize deposit, Zhaotong Maoping deposit, Lemachnag deposit, Ludian Xinzai deposit etc.) in the Sichuan-Yunnan-Guizhou Pb-Zn Metallogenic District are distributed mainly over northeast Yunnan. They have played an important role in the development of non-ferrous metal industry in China. The ore-finding method of Tectono-geochemistry is effective, and its application in the Huize Zn-Pb-(Ag-Ge) metallogenic district can be taken for a successful example in expanding the metal reserves for the depth and vicinity in the old mining district.
Detailed studies have shown the Huize district possesses unique metallogenic features, which present the ground for the application of Tectono-geochemical method: high ore grade ( (Pb+Zn)25%) and simple mineral composition (sphalerite, galena; pyrite);enrichment of Ag and dispersed elements in the ores; structural and lithological character (ore-bodies are distributed in the NE-trending compresso-shear fault zone between coarse-crystalline dolomite and silicified dolomitic limestone in the different strata); simple and limited wall-rock alteration (except for intensive dolomitization, hydrothermal alteration consists of limited silica, pyrite and clay in orebodies and near-ore country rocks); mineral zonation in the ore-bodies.
Based on detailed studies of the ore-forming conditions of this deposit, the features of fault mechanics and tectonites, the fault tectono-geochemical mapping is provided. It is suggested that the tectono-geochemical anomalies are indicatives of targets for the prognosis and localization of concealed ore-bodies at depth and the main ore-bodies are inclined in the direction, the anomalies reflect the obvious controls of structures over mineralization, the distribution characteristics of primary anomalies at the different levels implicates ore fluids would flow in the different direction, and the changes in the gradient of primary anomalies are indicative of the dipping direction and extension of concealed ore-bodies. The successful prognosis and localization of concealed ore-bodies in the Huize mine at the exploration lines 100 to 130 and depth along the exploration lines 44 to 62 at level 1571m have been confirmed by attesting engineering projects. Recent discoveries of the No. 8 and 10 ore-bodies have led to an increase in Pb-Zn metal reserves by near 2 Mt. As a result, the reserves in the mine come up to such an extent as to be super-large sized. This ore-finding method is of great instructive significance in localization-prognosis and evaluation of concealed Pb-Zn ore-bodies at depth and its vicinity in the Huize Pb-Zn district, as well as of the Pb-Zn deposits in northeastern Yunnan district and the same type deposits.
Granted jointly by the funds for Program for NCET in University (NCET-04-917), NSF of Yunnan Province (99D0003G), Collaboration Program of Yunnan (2000YK-04) and Project for the Distinguishing Discipline of KUST (2008).

 

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