| Liu gezhuang graphite ore deposit in Pingdu of Shandong Province is located in the west of connecting parts of two Ⅲ connecting parts of the tectonic units between Jiaobei uplift and jiaolei basin,that it is a large crystal graphite ore deposit. Liu gezhuang graphite ore deposit has a line belt of zonal distribution,and the most of graphite in the ore has a medium size of particle graphite crystal in scaly.The types of ore inclouds biotite-diopside-granulite,biotite granulite,biotite plagioclase gneiss.Through the diagram of metamorphic protolith restoration and analysis of the main trace elements,rare earth element geochemical characteristics,we found the original rock of Liu gezhuang graphite ore containing ore rock is a set of calcareous mudstone,carbonate,graywacke and felsic qualitative sandstone which has exhibited rock series characteristic of sedimentary rock. The value of the Sr/Ba, Rb/Sr show that the original rock of metamorphic rock samples is marine facies sedimentary rock,and the negative anomaly value of element Eu and Ce shows that the original rock of metamorphic rock is offshore-bathyal deposit.The value of MnO/TiO2 is in the scope of 0.059~0.059,and it means the tectonic environment is the active continental margin.Diagram of the relationship between the value of SiO2/Al2O3 and K2O/Na2 O shows the tectonic environment of metamorphic rock series is the active continental margin.Through the dating age data of U-Pb isotope in zircon,the age of the sedimentary for original rock of metamorphic rock series is about 2230±20ma,we found that the collision between continental an island arc on the west side of north China massif causes the block uplifting.On the edge of the continent,the offshore-bathyal etc semi-closed marine environment appeared,and the metamorphic protolith began accepting deposits.The range of zircon age 1870±20 ma means that the original rock is under the continuous regional hydrothermal metamorphism,after the early Proterozoic.Finally the original rock formed the metamorphic rocks whic h belong to amphibolite granulite facies under the condition of medium voltage high temperature,and form Liu gezhuang graphite ore deposit.The carbon isotope datas of graphite ore show that the main graphite carbon source of Liu gezhuang graphite mine is mainly organic carbon,and the carbon is likely to comes from mud shale containing organic matter.The type of Liu gezhuang graphite ore deposit is sedimentary metamorphic ore deposit. |
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