Petrological And Geochemical Characteristics Of Guilin Chicken Blood Jade And Its Indication For The Genesis

Guilin Chicken Blood Jade?GCBJ?is a kind of quartz jade,and the original rock is siliceous rock.The previous studies on geological occurrence,geochemical characteristics and deposit genesis are few.In this paper,the GCBJ of Shanglang and Pingye of Longsheng as the research objects,with the help of Polarizing microscope,X-ray powder diffractometer and other equipments,The mineralogical and petrological characteristics of GCBJ were analyzed.The major elements,trace elements and rare earth elements of GCBJ were analyzed by X-ray fluorescence spectrometer and inductively coupled plasma mass spectrometer.Combining the mineralogiacal,petrological and geochemical characteristics of GCBJ with the study regional geological tectonic movement and stratigraphic distribution characteristics,the formation of GCBJ was preliminarily discussed from the perspective of geochemistry.The GCBJ is dense and massive,Most of them are allotriomorphic equigranular texture,and some areas have porphyroblastic texture.The main component mineral of GCBJ is quartz,secondary minerals are hematite,dolomite,chlorite,pyrite,talc,etc.Pyrite is common in the GCBJ of Shanglang,talc is generally only found in the GCBJ of Pingye.The Co content of pyrite in GCBJ is 850ppm-1026.67ppm,Co>Ni,Co/Ni is between2.33-50,the ratio changes greatly,the average value is 23.38,which indicates that the formation of GCBJ is not only related to volcanism,but also affected by metamorphic hydrothermal fluid.The SiO₂ content of GCBJ is 85.34%-98.10%,with an average of 93.59%.The average ratio of Al/?Al+Fe+Mn?is 0.19.Most of the samples fall on the Fe-rich end of Al-Fe-Mn Triangle diagram,showing that the geochemical characteristics of hydrothermal sedimentation,it indicates that the GCBJ may be the product of hydrothermal sedimentation.The content of trace elements is generally low,U/Th is greater than 1,it also shows the characteristics of hydrothermal sedimentation.The total REE is very low,?Ce is 0.90-1.12,the average is 1.02,there is no obviousanomaly,the average value of?Eu is 1.96,obviously positive anomaly,?La/Ce?_N is 1on average,which is different from the characteristics of rare earth elements in typical hydrothermal sedimentary rocks,but it shows that the formation of GCBJ is closely related to hydrothermal sedimentation,and is greatly influenced by hydrothermal activity.The material source and formation of GCBJ experienced multiple stages geological events and was deeply affected by hydrothermal metamorphism.Its geochemical characteristics show that the formation of GCBJ is closely related to hydrothermal activities,and the main elements show the geochemical characteristics of hydrothermal sedimentation.Therefore,the genesis of GCBJ are complex and diverse,which is the result of multiple stages and multiple causes.