Constituted Characteristics Of Ore Chemistry And Mineralogical Mapping Of The Dongping Gold Deposits, Hebei Province

This study is supported by " Study of mineral character and the mechanism of tellurium bearing gold deposit" project of China Geology Survey. Dongping gold deposit is located at the middle piece of north margin of Huabei plate, in the Zhangjiakou-Chicheng-Chengde gold belt, and in the contact zones from the south margin of Shuiquangou alkaline complex. The study is about the chemical composition character of the ores and mineralogical mapping by the main gold-bearing minerals pyrite and quartz.1、The chemical compositon of altered rock type ore shows grouping and vertical staging in Dongping. Most of the ore samples are alkaline quasi aluminum syenite, which are alkali rich, silica rich and aluminum poor. In the process of mineralization, there are K, Na, Si taking in and Al, Ti, Fe, Mg, Ca, P taking out. The result of ore-forming elements classification demonstrates that Te, Ag, As, Hg, Co, Ni, Cr, Mo are related to Au, which shows the type of gold mineral, chemical propertiy, metaliferous mineral association combination and later supergenic metallogenesis. The vertical change of ore-forming elements indicates that centered with1204and1374, there are two period hydrothermal mineralization and super enrichment metallogenesis overlying.2、The crystalline form and composition of pyrite are related to gold-carrying. In the early mineralization, there are a lot of coarse grain cubical pyrites and milky quartzes, but low gold-carrying. In the peak mineralization time, there mainly are fine grain cubical pyrites, pentagonal dodecahedral quartzes and gray white quartzes, and rich of gold. The peak time gold-bearing pyrite samples are83.33%of all the samples. The main type of existence include inclusion gold and fissure gold. The chemical formula calculating result of pyrite crystalline (such as (Fe1.o32Co0.001Ni0.001)1.034S1.966) shows that the pyrite is with poor sulfide.3、The conductance of pyrite is positive correlated with gold grade. In the peak mineralization period, pyrite is simple N type, and thermoelectric coefficient is positive correlated with gold grade. The mathematical expression of fitting is Y=0.048|X|-8.414, Y∈(1,10). The high value region of thermoelectric coefficient isoclines is identical with the high value region of gold grade isoclines. It can be foretold that Line11will extend well in deep layers, and it is proved by depth portion drilling.4、The thermoluminescent character of quartz is related to gold. The peak period of thermaluminecsent spectral peak include4types:two peaks (first low peak, second high peak), half single peak, full single peak, two peaks (first high peak, second low peak), and the height of peak increases, area of peak increases and gold grade increases.5、The gold grade and quartz thermoluminescent isoclines are coherence. By comparing the peak height, peak temperature, halfpeak breadth and peak area of both the isoclines images, it can be predicted that Line10and Line11will extend well to the deep, and it is proved by depth portion drilling.