地质学报2017，Vol.91Issue(9)：2004-2020,17.
黔南罗甸中晚泥盆世硅质岩类沉积环境及其形成的大地构造背景
Depositional Environments and Tectonic Background of the Middle-Late Devonian Siliceous Sediments in Luodian, South Guizhou
摘要
Abstract
Deep-water sedimentary siliceous rocks and limestones, widely developed in Luodian, South Guizhou during Middle-Upper Devonian time, belong to a special formation type of siliceous rocks, because their formation type is distinctly different from siliceous rock developed within the island arc-type or accretionary environments.The petrological, mineralogical, and geochemical study was carried out for 42samples collected from the Middle-Upper Devonian siliceous sediments at Mengjiang and Guoshizhai in Luodian county, South Guizhou.The results reveal that the middle Devonian siliceous sedimentary rocks are high in Al2O3(0.62％～22.1％), TiO2(0.01％～0.84％),Fe2O3(0.41％～10.5％) and ∑REE content(7.87×10-6 ～319 × 10-6),and Ce/Ce* (0.51～0.96), and relatively low in Y/Ho(26.6～37.0, ave.30.8) and (La/Ce)N(1.06～1.99,ave.1.28);while the Mengjiang siliceous sediments of Upper Devonian are low in Al2O3(2.42％～10.6％), TiO2 (0.06％～0.43％), Fe2O3 (0.62％～2.65％), ∑ REE(28.7×10-6～163×10-6), Ce/Ce*(0.45～0.82), and relatively high inY/Ho(28.2～36.7,ave.34.2)and (La/Ce)N(1.34～2.34,ave.1.82).Except the effect of SiO2 dilution, the siliceous sediments in the study area have greatly variable REE contents and indicate multiple sources in origin, with large part from seawater from Middle to Upper Devonian and minor from terrigenous clastics.The discrimination diagrams of Al2O3/TiO2-Al(Al+Fe+Mn), Al-Fe-Mn and (∑REE-+-Y)-SiO2/Al2O3, and the major and rare earth element geochemical characteristics of the Middle-Upper Devonian siliceous sediments at Guoshizhai and Mengjiang in Luodian, indicate that these siliceous sediments formed in a normal marine sedimentary environment, with the depositional environment changing from restricted margin rift basin to an open-ocean rift basin during Middle to Upper Devonian.This study is of important value for further understanding the evolution for the Shuicheng-Ziyun-Nandan rift basin in the Late Paleozoic and Youjiang basin during Middle to Upper Devonian.关键词
硅质沉积物/沉积环境/构造背景/中上泥盆统/罗甸/贵州Key words
siliceous sediments/sedimentary environments/tectonic setting/Middle-Upper Devonian/Luodian/Guizhou引用本文复制引用
高军波,杨瑞东,郑禄林,魏怀瑞,程伟..黔南罗甸中晚泥盆世硅质岩类沉积环境及其形成的大地构造背景[J].地质学报,2017,91(9):2004-2020,17.基金项目
本文为贵州大学人才引进项目(贵大人基合字(2014)54号)、贵州省科技合作计划项目(黔科合LH字[2015]7663号)和国家自然科学基金项目(编号41503030)联合资助成果. （贵大人基合字(2014）
