地质论评Issue(3)：499-510,12.DOI:10.16509/j.georeview.2015.03.004
湘中震旦纪-寒武纪之交硅质岩地球化学特征及成因环境研究
Geochemical Characteristics of Siliceous Rocks During the Transition from Sinian(Ediacaran)to Cambrian in Central Hunan and Its Implication for Genesis and Sedimentary Environment
摘要
Abstract
The South Block was in the background of extensional tectonics during the transition from Sinian (Ediacaran)to Cambrian,and the siliceous rocks developed widely in southest margin of Yangtze block.The deep-water Sinian— Cambrian sections in central Hunan include the Doushantou Formation,Liuchapo Formation, composed mainly of bedded siliceous rocks with Si-rich and C-rich shale deposits,which is also overlain by the Niutitang Formation.Based on the analyses of major elements and rare earth elements,it was conclude that the Sinian— Cambrian siliceous rocks of central Hunan contain high contents of SiO2 (generally over 92%)and have high Al /(Al +Fe +Mn)value (generally higher than 0.6).The shale PAAS-normalized REE patterns for the Sinian—Cambrian siliceous rocks show weak to intermediate negative Ce anomalies and strong enrichment in HREEs relative to LREEs.Ce /Ce*,LaN /YbN and Y /Ho values for the siliceous rocks of Sinian Doushantuo Formation are 0.34 ~0.54,0.05 ~0.10 and 38.00 ~51.44;the siliceous rocks from Sinian Liuchapo Formation and Cambrian Niutitang Formation have similar REE geochemical characteristics,Ce /Ce*,LaN /YbN and Y /Ho values for two groups of samples are 0.70 ~0.85,0.06 ~0.37,35.91 ~46.79 and 0.58 ~0.78,0.26 ~0.40, 34.75 ~45.58 respectively.The characteristics of major and rare earth elements reflect that these siliceous rocks formed in the deep-water basin far from continent and extensional faulting belts where terrestrial material and hydrothermal activities had no obvious effect on them.Although terrestrial input had an increasing tendency from Sinian to Cambrian,the origin of silica may derived from the thriving of the siliceous plankton.Sedimentary basin in central Hunan seemed like a passive continental margin basin during the transition from Sinian to Cambrian.关键词
震旦纪(埃迪卡拉纪)-寒武纪之交/华南/硅质岩/地球化学/沉积环境Key words
Sinian (Ediacaran) Cambrian/South China/siliceous rock/geochemistry/sedimentary environment引用本文复制引用
张亚冠,杜远生,徐亚军,余文超,黄虎,焦良轩..湘中震旦纪-寒武纪之交硅质岩地球化学特征及成因环境研究[J].地质论评,2015,(3):499-510,12.基金项目
本文为国土资源部公益性行业科研专项经费“上扬子地块东南缘锰矿国家级整装勘查区成矿系统与深部找矿关键技术研究及示范”（编号201411051）、中国地质调查局地质调查工作项目“上扬子地块东南缘锰矿成矿地质背景研究”（编号12120114016701）和国家自然科学基金资助项目（编号41272120）的成果。 （）
