| The Panzihua titanomagnetite deposit is located in the middle of the Kang-Dian axis,in part of the Emeishan large igneous province,where mineral resources are abundant and diverse,especially with huge reserves of titanomagnetite resources.The Panzhihua rock mass can be divided into two parts:the upper gabbro and the lower peridotite.Based on the rhythm of rock or ore body,the ore-bearing rock mass can be divided into four lithofacies,the lower dark gabbro facies,the middle bedded gabbro facies,the upper light gabbro facies and the marginal facies.Among them,the rock facies in the lower part can be divided into 5 rhythm cycles,central rock facies 6 rhythm cycles,the upper part without clear rhythmic cycles.In each rhythm cycle,Fe-Ti oxides content gradually decreases from bottom to top,opposite for silicate minerals.The content of SiO2 among the main elements of Panzhihua gabbro is between 28.33%and 46.67%;that ofNa2O + K2O between 0.71%and 3.63%;that of TiO2 between 2.74%and 8.54%;A/NCK ratio is from 0.74to1.38,indicating a peraluminum-low potassium tholeiitic alkaline rock series.The content of SiO2 among the main element of associated Emeishan basalt is between 45.36%and 59.57%,that of Na2O + K2O between 1.24%and 6.43%,that of Ti02 content is between 2.21%and 5.87%,The A/NCK ratio is from 0.82%to 1.47%,indicating a peraluminum-calcium alkaline-sub-alkaline rock series.Panzhihua ore bearing gritite belongs to light rare earth enrichment type,light and heavy rare earth fractionation is common,in addition to gabbro in the lower lithofacies with significant Eu anomaly,all shows a non-obvious Eu positive anomaly;associated Emeishan basalt belongs to Light rare earth enrichment type,heavy rare earth fractionation is more obvious,with anobvious Eu positive anomaly.The content of trace elements in Panzhihua ore-bearing gabbro is generally low,and loss of Rb,Th,u,La,Ce and other incompatible elements,high field strength elements Y,Yb,Lu in individual samples below average of that in primitive mantle.The content of La,Ce,Nd,Sm,Y,Yb and Lu in the ore bearing gabbro is lower than that in light and fine little or none ore gabbro.According to the high Ti characteristics of Panzhihua gabbro,its origin may be similar to Emeishan high-titanium basalts,and may derived from the mixing between weak partial melting of the upper mantle and strong partial melting of the lower lithosphere.The origin of the Emeishan basalt derived from weak partial melting of the lithosphere and mantle.And both are contaminated by the crustal material,of which the gabbro is contaminated by the lower crust and the basalt by the upper crust.Mineral microelectronics probe analysis shows that the occurence of V,Fe,Ti and other ore-forming elements ohas obvious regularity:1)in different rhythmic layers of iron-rich and iron-poor horizons,olivine FeO content is low in iron-rich horizons while high in iron-poor horizons,while oppisite for MgO content and its corresponding Fo grades.2)In plagioclase in each rhythm layer,the content of CaO and Al2O3 gradually decreased from bottom to top,while the Na2O content increased gradually,reflecting the plagioclase An grade has a gradual increase trend from top to bottom.3)The content of MgO and TiO2 in bulk ore is the highest inilmenite and lowest for FeO and Fe2O3,while the content of these oxides in the iron-poor layer is opposite,with no obvious change for these oxides in iron-rich layer.The content of MgO and Ti02 in magnetite has the same regularity as ilmenite,and the content of these two oxides in ilmenite is positively correlated with that of these oxides in magnetite,while inversely related to Al2O3.The above work has found the variation rule of mineral elements in different lithofacies and different minerals,and it is revealed that the Panzhihua ore-bearing rock mass may be a complex rock mass supplemented with multi-episode iron-titanium magma,each supplement is accompanied by an increase in the degree of oxygen fade.The enrichment of ore-forming elements is not only affected by the composition of the parent magma of ore-bearing rock,but also by the nature of magma,oxygen fugacity,differentiation degree and volatile components.The multi-period pulsation superposition of ore-bearing rock mass,thecrystallization differentiation and gravity differentiation of deep magma are the most important controlling factors of bottom mineralization.The intrusion and eruption of multi-stage magma associated with the action of mantle plume is not only beneficial to the enrichment and precipitation of mineral elements such as V-Fe-Ti,but also the formation of associated copper-nickel sulfide deposits in the region,constituting a relatively complete magmatic mineralization series with genetic relationship.According to the difference of ore-forming elements in different mineral phases in the feature set for the beneficiation process and provide technical support. |
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