Typomorphic Characteristics Of Pyrite And Deep Prognosis Of The Haoyaoerhudong Gold Deposit,Inner Mongolia Autonomous Region,China

The Haoyaoerhudong gold deposit locates in the northwest margin of the NorthChina Craton. It is produced out of the sedimentary strata among the Bayan OboGroup of the mesoproterozoic. It is a medium temperature hydrothermal gold depositwhose ore-bearing rock is carbonaceous slate. The ore bodies mainly originate fromcarbonaceous slate and carbonaceous phyllite of the Bilute formation (Pt2byb1-Pt2byb2)in the Bayan Obo Group. The ore, which is found in layer shape or layer-like shape, isrigorously controlled by the stratum, the fracture zone and the foliated zone. Based onthe research of the geological features and the main ore-controlling factors of the golddeposit, this thesis aims to analyze the distribution characteristics of pyrite's shape,pyroelectricity, microelement and its relationship with mineralization. The mainachievement and understanding are demonstrated as follows.Firstly, the pyrite commonly appears in single shapes of cube-a and pentagonaldodecahedron-e and in the combination shape of such cubic crystals as "a" plus "e","a" plus "o","a" plus "e" plus "o" and "e" plus "o". Octahedron-o appears only in arelatively few samples. Moreover, the relationship between crystal morphology andgold grades shows that the frequency of "e"habit crystals has positive correlation withgold grades. From this finding, it can be predicted that mineralization with goodquality exists in the depth of exploratory lines78-79,98-100and102-104, a widerange of enrichment appears in200-400meters, and mineralization will be furtherstrengthened in Line100and below500meters. Moreover, the crystal characteristicsof the pyrite show that the exploring layer of the mining locus lies in the middle-uppersection of the ore body.Secondly, all types of pyroelectricity of the pyrite are almost N type and itspyroelectricity coefficients concentrate on-150～-250μV/℃. The mean changes ofthe depth of the ore locus αare quite regular. It can be found that α has distinctlypositive correlation with the gold grades. From this finding, it can be predicted thatthe degree of mineralization will be rising in Line100, below455meters, be poor inthe depth of Line99and have a little rise in depth of in Line77. According to thefrequency histogram of pyroelectricity coefficients in each exploratory line, it can beinferred that the ore-forming has a promising prospect in the depths of Line78-80,Line83, Line97-98and Line102. As the pyroelectricity coefficients in different depths around stay at-200μV/℃and the types of pyroelectricity change slightly, it canbe predicted that this deposit has a large scale and a deep extension.Lastly, by correlative, clustering and factorial analyses about the elevenmicroelements that have close relationship with ore-forming, it can be found thatzoning sequence of primary halos is Co, Sb, Ba-Pb, Zn, Cu-Ni, Cu-W, Bi and Mofrom heading to ending. If Cu, Ni,Pb and Zn concentrate in Line101-103at the sametime, it can be inferred that this locus is the middle part of the ore body. Taking thefeatures of low gold grades and large scales into consideration, that the ore body has awide extension in Line101-103can be predicted. Sb, Ba, Bi, Co, Ni and Wconcentrate heavily in the north of Line97-100, and that should be the result ofsuperimposition of two mineralization periods. Based on this fact, we can predict thatthere are concealed ore bodies in depth. By factor analysis, we can find that theattribute of drilling holes has large scale changes in300-400meters depth. Meanwhile,the pyroelectricity coefficients have a sharp fluctuation in this area. Based on this, itcan be predicted that there are hydrothermal ore-forming activities for twice or morein this area. Below500meters, the ore bodies will still have a wide extension and theore-forming has a promising prospect.