摘要
下白垩统洛河组含水层是鄂尔多斯盆地南部大佛寺井田煤炭开采的主要充水含水层,为查明洛河组沉积期古环境、古气候及物质来源,系统采集样品开展微量元素及稀土元素地球化学分析。结果表明:洛河组砂岩氧化还原判别指标数值较低,U/Th为0.17~1.07,平均0.37;Ni/Co为1.14~2.17,平均1.67;AU为-1.33~7.29,平均0.28;Ce_(anom)为-0.21~-0.07,平均-0.17,指示洛河组沉积期为氧化环境;Co含量为4.38~20.06,平均8.21,定量计算出沉积期的平均古水深为4.14 m,属于浅水环境;Sr/Ba比值中等,为0.33~1.99,平均0.82;Th/U比值较高,为0.93~5.94,平均3.10,指示洛河组沉积期为陆相淡水环境;Sr/Cu比值较高,为12.90~362.84,平均95.12;Rb/Sr比值较低,为0.13~0.72,平均0.29,指示干燥气候背景下沉积,大佛寺井田洛河组为干燥气候背景下氧化环境中的陆相浅水沉积。洛河组砂岩具有与北秦岭较一致的稀土配分模式,指示物源来自北秦岭,主要为长英质、基性岩混合物源和安山岩岛弧物源。
The Lower Cretaceous ultra-thick Luohe Formation aquifer is the main water-filled aquifer for coal mining in the Dafosi wellfield in the southern part of the Ordos Basin.In order to identify the palaeoenvironment,palaeoclimate and its material provenances,samples of sandstones were systematically collected for trace element and rare earth element geochemical analysis.The results show that the redox indicators of the sandstones of the Luohe Formation are low,with U/Th ranging from 0.17 to 1.07,with an average of 0.37;Ni/Co ranging from 1.14 to 2.17,with an average of 1.67;AU ranging from-1.33 to 7.29,with an average of 0.28;Ce_(anom)ranging from-0.21 to-0.07,with an average of-0.17,indicating an oxic environment in the water column during the deposition of the Luohe Formation.Co contents range from 4.38 to 20.06,with an average of 8.21,quantifying the average paleo-depth of 4.14 m during the deposition period,which is a shallow water environment.Sr/Ba ratios are moderate,ranging from 0.33 to 1.99,with an average of 0.82;Th/U ratios are high,ranging from 0.93 to 5.94,with an average of 3.10,indicating a terrestrial freshwater environment during the deposition of the Luohe Formation.Sr/Cu ratios are high,ranging from 12.90 to 362.84,with an average of 95.12;Rb/Sr ratios are low,ranging from 0.13 to 0.72,with an average of 0.29,indicating deposition in a dry climatic context.It reflects that the Luohe Formation in the Dafosi Wellfield is a terrestrial shallow water deposit formed in an oxic environment and a dry climatic context.The rare earth elements patterns of the sandstones from the Luohe Formation are more consistent with the North Qinling,indicate that its provenance is from the North Qinling Mountains,which is mainly a mixture of felsic and basaltic provenances and andesitic island arc provenances.
作者
蔡玥
罗旭东
周对对
刘家鹏
何静
汪庆国
李登科
魏少妮
CAI Yue;LUO Xudong;ZHOU Duidui;LIU Jiapeng;HE Jing;WANG Qingguo;LI Dengke;WEI Shaoni(College of Geology and Environment,Xi’an University of Science and Technology,Xi’an 710054,China;Geological Research Institute for Coal Green Mining,Xi’an University of Science and Technology,Xi’an 710054,China;Shaanxi Provincial Key Laboratory of Geological Support for Coal Green Exploitation,Xi’an 710054,China;Shaanxi Binchang Dafosi Mining Co.,Ltd.,Binzhou 713500,China)
出处
《西安科技大学学报》
CAS
北大核心
2023年第4期752-760,共9页
Journal of Xi’an University of Science and Technology
基金
陕西省教育厅一般专项科研计划项目(21JK0760)
自然资源部煤炭资源勘查与综合利用重点实验室开放课题项目(KF2020-1)
西安科技大学博士启动项目(2020QDJ012)
陕煤化工集团科技项目(DFS-SCFW-2022065)。
关键词
地球化学
洛河组
古沉积环境
物质来源
geochemistry
Luohe Formation
paleosedimentary environment
material provenances
