Study On The Sedimentary Characteristics And Metallogenic Relationship Between The Main Ore - Forming Deposits In Yanmen Copper Mine, Yunna

Yimen Copper Belt is an important mine copper resources in central Yunnan, Tongchang copper mine is one of the major copper deposits in eastern mine belt of Yimen.In this paper, the "Tongchang and peripheral copper forming rules and prospecting prediction research project in Yimen" basis,through field geological survey shows that, Tongchang mining deposition-diagenesis and mineralization characteristics is obvious, therefore, choose Tongchang main mining seam, Luoxue formation Kunyang group, to study. From the temporal and spatial variation of ore bearing layer and structure and rock combination, sedimentary microfacies, rock geochemistry and so on Luoxue formation were studied, facies sedimentary geochemical characteristics and sedimentary environment characteristics. The research results show that:1. Make a space and time comparative study of Yimen Tongchang Kunyang group central Yunnan Luoxue formation, we found that along the direction of the NE-SW Tongchang area of ancient sedimentary basin has "Two concave clip a raised" tectonic pattern, and NE side (17 lines north) ore better, SW side (the 23 line to the South) ore mineralization weak.2. Carbonate rocks with reference to eighty’s Fl gel and Wilson basic model and microfacies type, and on the basis of the survey and indoor rock slices section identification field, the Luoxue formation dolomite is divided into eight microfacies types, MF1 Microcrystalline dolomite, MF2 laminated dolomite, MF3 oolitic dolomite, MF4 algal dolomite, MF5 clastic dolomite, MF6 siliceous dolomite, MF7 silicified dolomite, MF8 argillaceous dolomite.3. Study on the sedimentary geochemical characteristics of the main ore bearing strata in the study area of dolomite of major elements, trace elements, REE that:①Different types of rock chemical composition is different, the close relation with the rock lithology. First Luoxue group (Pt2l1) dolomite SiO2+Al2O3 average value is significantly high, rich in terrigenous (muddy), is a high impurity dolomite. Second Luoxue group (Pt2l2) dolomite generally siliceous bands or siliceous mass, total average total CaO+MgO high, low Al2O3, high SiO2, is a siliceous dolomite type. Third Luoxue group (Pt2l3) dolomite composition and snow two overall similarity. The main ore bearing strata (Pt2l2) in Cu, Co, Ba, Zn, Sb average content relative First and Third Luoxue formation (Pt2l1、Pt2l) is higher, which is related to mineralization. Different types of rock samples in REE patterns have obvious Right deviationist trend, LREE enrichment, hree depletion. Second Luoxue gruop δEu average value is 0.78, showed slight to medium negative Eu anomaly, reflecting the whole sedimentary environment of partial reduction, in northern mining area of Eu anomalies are obvious.②Sedimentary geochemical indexes of [Sr/Ba, B/Ga, m, V/(V+Ni), Mg/Ca, Sr/Cu, Fe2+/Fe3+], reflect Luoxue formation sedimentary period sedimentary environment experienced weak reduction (Pt2l1), reduction (Pt2l2) and weak reduction (Pt2l3) and inshore seawater environment (Pt2l1), brackish water (Pt2l2-Pt2l3) evolution process. In space, during the deposition of Luoxue formation second sections, the northern tidal flat depressions with high salinity (Sr/Ba=0.540, B/Ga=4.011) and strong reduction (Fe2+/Fe3+=14.706) and other marks, the southern tidal flat depressions with salinity (Sr/Ba=0.25, B/Ga=2.6) and reduction of weak (Fe2+/Fe3+=2.54) characteristics.4. The research of sedimentary facies marks indicate that the ore bearing layer, middle uplift (tidal reef flat facies) conical, spherical, columnar stromatolites development, visible wavy bedding, lenticular bedding structure and scour structure, strong water power. Southern and Northern tidal flat depressions layered or irregular banded stromatolite development. The northern tidal flat depression phase visible laminated structure, convolute bedding, cross bedding, wavy bedding, scour structure, such as the strong hydrodynamic disturbance structure, strong. The southern tidal depression phase common laminated structure, hydrodynamic is strong-weak.5. The macroscopic geology, geochemistry and sedimentary facies study shows that mining sedimentary diagenetic type mineralization largely controlled by lithofacies palaeogeography environment,17 line to the north of the tidal flat lowlands into relatively closed energy belt, salinity is higher, in a relatively reducing environment, conducive to the metallogenic substance accumulation, sedimentary diagenetic type ore body development better is the main mineralization. The 23 line to the south of the tidal flat depressions communicat with the sea, closed poor, seawater salinity medium, in weak reduction environment, not conducive to mineral aggregation.