地质科学2017，Vol.52Issue(1)：186-202,17.DOI:10.12017/dzkx.2017.012
四川盆地及周缘五峰组—龙马溪组钾质斑脱岩特征及其地质意义
The characteristics and geological significance of the K-bentonite in Wufeng Formation and Longmaxi Formation in Sichuan Basin and its peripheral areas
摘要
Abstract
The K-bentonite which contains abundant geochemical information is widely distributed in Wufeng Formation and Longmaxi Formation in Sichuan Basin and its peripheral areas.In order to make a further study of the geological significance of the K-bentonite in black shale,we have learned the K-bentonite by the methods of XRD,XRF,ICP-MS and combined with the outcrop observation.Researches show that the bentonite in the study area mainly composed of illite,plagioclase,quartz and other mineral composition.The main elements mainly composed of SiO2,Al2O3,Fe2O3,K2O and the K2O/Na2O is 15.54 ～ 270.The trace elements are rich in Th,U,Pb,Zr,Hf,TaandRb,Cs,Ba,and deplete in La,Ce,Sr,Sm,Eu.The ∑REEis 19.58×10-6～ 383.88×10-6,average is 105.43×10-6;LREE/HREE is 0.74 ～ 12.67,average is 3.93;and rich in LREE,deplete in HREE.The Light and heavy rare earth elements differentiation is obvious,Eu negative abnormity,and there is no evidently Ce abnormity.Comprehensive analysis suggests that:1) The bentonites in Wufeng Formation and Longmaxi Formation in Sichuan Basin and its peripheral areas have the characteristics of high potassium low sodium,and coincide with the K-bentonite.The bentonites have similar characteristics with the same material sources.2) The tectonic environment of original rock mainly is the island arc environment,also exists certain intraplate environment,volcanic ash may mainly come from the North Qinling Mountains.3) Volcanic ashes can improve the ocean surface primary productivity and provide material basis for the high quality shale.关键词
四川盆地/五峰组/龙马溪组/钾质斑脱岩/地球化学Key words
Sichuan Basin/Wufeng Formation/Longmaxi Formation/K-bentonites/Geochemistry分类
天文与地球科学引用本文复制引用
卢斌,邱振,周杰,董大忠,王红岩,薛华庆,周尚文..四川盆地及周缘五峰组—龙马溪组钾质斑脱岩特征及其地质意义[J].地质科学,2017,52(1):186-202,17.基金项目
国家自然科学基金项目(编号:41602119)、国家重点基础研究发展计划“973”项目(编号:2013CB228001)和中石油廊坊分院项目(编号:XN41601,XN41603,XN11304)资助. （编号:41602119）
