Geochemistry of Upper Devonian Hydrothermal Mammilated Chert Guangxi,Southwest China

查看全文 作　　者：[1]陈先沛;[1]陈多福 机构地区：[1]Institute of Geochemistry,Academia Sinica 出　　处：《Chinese Journal Of Geochemistry》索引1990年第9卷第1期,共8页 摘　　要：The mammilated chert(MC) studied in this paper is a kind of silica-rich concretion(SiO2 93%) occurring in the Upper Devonian argillaceous silicolites(SiO2≈88%)in Mugui,Guangxi.Impurity components in the MC are relatively low and show systematic variationhs as compared with the country rocks.Abundances of Mg,Si,Ti,Fe,Mn,U and Th are characteristically similar to those of recent and fossil hot-water sediments,Moreover,the MC is also characterized by low REE baundance,LREE>HREE,apparent negative Ce anomaly and moderate positive Eu anomaly,OXygen isotope data show that the formation temperature of the MC is about 20℃,higher than that of the host rock.The results of geochemical,geological and lithological studies suggest that the MC may have been formed through metasomatism,fillinn and crystallization beneath the sedimentary basin during the Devonian period. 关 键 词：地球化学 广西 热液 上泥盆纪 稀土元素 黑硅石