桂林鸡血玉的成因探讨

Discussion on the Origin of Guilin Chicken Blood Jade

借助偏光显微镜、电子探针等现代仪器设备,对桂林鸡血玉的成因进行分析和探讨。桂林鸡血玉产地的区域地质背景复杂,围岩的主要矿物组成为方解石和白云石,次要矿物有云母、绿泥石、赤铁矿、磁铁矿、钛铁矿等,根据次要矿物的分布形式及化学成分的分析可知次要矿物为后期进入的矿物。桂林鸡血玉的形成经历了四堡运动、加里东运动、印支运动、燕山运动、喜山运动等构造运动,经过海底火山沉积作用、岩浆热液作用、变质作用等各种地质作用,这些运动和作用引起了石英岩中裂隙的产生和铁化合物及其他矿物的进入。在桂林鸡血玉中可见浸染状赤铁矿分布在石英颗粒之间或裂隙中,杂质矿物也分布在石英颗粒的间隙,而鸡血玉中多期裂隙的存在说明经历了多期构造运动,同时也说明桂林鸡血玉为多种作用共同产生的结果。

The origin of Guilin Chicken Blood Jade(GCBJ)was analyzed and discussed by polarizing microscope,EPMA,and other modern equipment.The regional geological background of the producing area of GCBJ is complex.The main mineral composition of surrounding rock is calcite and dolomite,and the minor minerals are mica,chlorite,hematite,magnetite,ilmenite,etc.According to the distribution form and chemical composition analysis of secondary minerals,it was observed that the secondary minerals are the minerals in the later stage.The formation of GCBJ experienced such tectonic movement as the Sibao movement,the Caledonian movement,the Indosinian movement,the Yanshan movement and Himalayan movement.The various geological processes such as submarine volcanic sedimentation,magmatic hydrothermalism and metamorphism caused the formation of fractures in quartzite and the entry of iron compounds and other minerals.The disseminated hematite existed in GCBJ distributed among the quartz particles or in the cracks.The impurity minerals were also distributed in the interstitial quartz grains.And the presence of multistage fissures in GCBJ indicated that it experienced multistage tectonic movements.At the same time,it also shew that GCBJ was the result of multiple processes.