粤北丹霞盆地上白垩统丹霞组锦石岩段顶部泥岩岩石地球化学特征及其地质意义  

Geochemical characteristics and geological significance of mudstone at the top of Jinshiyan section, Upper Cretaceous Danxia Formation, Danxia Basin,northern Guangdong Province

作　　者：刘富军 杨庆坤[2] 郭福生[2] 孙传敏[1] 陈留勤[2] 华琛[2] Liu Fujun;Yang Qingkun;Guo Fusheng;Sun Chuanmin;Chen Liuqin;Hua Chen(College of Earth Sciences,Chengdu University of Technology,Chengdu 610059;School of Earth Sciences,East China University of Technology,Nanchang 330013)

机构地区：[1]成都理工大学地球科学学院,成都610059 [2]东华理工大学地球科学学院,南昌330013

出　　处：《地质科学》2019年第4期1237-1251,共15页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金项目(编号:41772197);韶关市丹霞山管理委员会科学研究项目(编号:DXSGEO2018001);江西省自然科学基金项目(编号:20171BAB213026);江西省教育厅科技计划项目(编号:GJJ170441)资助.

摘　　要：丹霞山是"中国丹霞"世界自然遗产的典型代表,目前对其成景地层上白垩统丹霞组沉积环境的研究程度不高,尤其对锦石岩段沉积环境还存在较大争议.锦石岩段以厚层—巨厚层状中-粗砂岩为主,发育大型交错层理,夹中薄层—极薄层状泥岩、粉砂质泥岩以及钙质层.本次采集的锦石岩段顶部中层状泥岩样品的黏土矿物成分以伊利石为主,稀土总量较高,ΣREE=191.19×10^-6~308.73×10^-6,轻、重稀土分异明显,轻稀土富集,δEu=0.52~0.63,负异常明显,δCe=0.91~1.27,Ce无异常,古盐度=10.74‰~16.21‰、B/Ga=3.89~5.04、V/(V+Ni)=0.74,代表了在干旱到半干旱的气候环境下,缺氧条件下的半咸水沉积水体,可能与晚白垩世中期Campanian期东亚中纬度地区的干旱古气候条件相关.短期有淡水注入,可能与其暂时性河道发育有关.La/Yb-ΣREE图解和Hf-La/Th图解研究表明,丹霞组锦石岩段泥岩的母岩物质成分以长英质和基性岩为主,具有岛弧属性.Danxiashan is a typical representative of the world??s natural heritage“China Danxia”. The study on the sedimentary environment of the Upper Cretaceous Danxia Formation is low, especially to Jinshiyansi section of Danxia Formation. In this paper, the mudstone in Jinshiyan section of Danxiashan Formation was studied by means of sedimentology and lithogeochemistry. The Jinshiyan section of the Danxia Formation is dominated by thick layered aeolian sandstones with thin layered mudstone, silty mudstone and calcareous layer. The ΣREE of mudstone sample in the top is high mainly is illite.ΣREE = 191.19×10^-6~308.73×10^-6, is relatively high, LREE and HREE are obviously differentiated, LREE is enriched,δEu = 0.52~0.63,δCe = 0.91~1.27, paleosalinity = 10.74‰~16.21‰, B/Ga = 3.89~5.04, V/(V+Ni)= 0.74. The samples are mainly in the semi-arid and arid region in the diagram of SiO2 VS. Al2O3+K2O+Na2O. It can be seen that the mudstone strata in Jinshiyan section of Danxia Formation was formed in the drought and semi-drought and anoxic conditions. In the Jinshiyan Period of the Late Cretaceous, Danxia Basin had a dry surface sedimentary environment which may be related to the arid paleoclimate conditions in the middle latitude region of East Asia in Campanian Period. Short-term fresh water injection may be related to temporary channel development.

关 键 词：丹霞盆地 丹霞组 古气候 

分 类 号：P534.53[天文地球—古生物学与地层学] P588[天文地球—地质学]