关中盆地新近系泥岩地球化学特征:物源和古沉积环境恢复  

Geochemical characteristics of Neogene mudstone in Guanzhong Basin:Provenance and paleosedimentary environment restoration

作　　者：兰华平 任战利[1,2,3] 张莹 祁凯 邢光远[1,2] 夏岩 冯梦媛[6] LAN Huaping;REN Zhanli;ZHANG Ying;QI Kai;XING Guangyuan;XIA Yan;FENG Mengyuan(State Key Laboratory of Continental Dynamics,Northwest University,Xi’an 710069,Shaanxi,China;Department of Geology,Northwest University,Xi’an 710069,Shaanxi,China;Key Laboratory of Exploration and Development of Multiple Energy Resources,Xi’an 710069,Shaanxi,China;Research Institute of Yanchang Petroleum(Group)Co.,Ltd.,Xi’an 710075,Shaanxi,China;Exploration and Development Research Institute of PetroChina Changqing Oilfield Company,Xi’an 710018,Shaanxi,China;Shaanxi Yanchang Petroleum(Group)Co.,Ltd.Natural Gas Research Institute Branch,Xi’an 710075,Shaanxi,China)

机构地区：[1]西北大学大陆动力学国家重点实验室,陕西西安710069 [2]西北大学地质学系,陕西西安710069 [3]西安市多种能源资源勘探开发重点实验室,陕西西安710069 [4]陕西延长石油(集团)有限责任公司研究院,陕西西安710075 [5]中国石油长庆油田分公司勘探开发研究院,陕西西安710018 [6]陕西延长石油(集团)有限责任公司天然气研究院分公司,陕西西安710075

出　　处：《地质通报》2024年第10期1801-1817,共17页Geological Bulletin of China

基　　金：陕西省重点研发计划项目《关中盆地中深层地埋管换热可持续开发关键技术研究与示范》(编号:2021ZDLSF05-12);陕西燃气集团有限公司项目《华州-华阴地区3口地热井井位论证及华州矿区地热资源综合评价技术》;长庆油田分公司勘探开发研究院合作项目《关中盆地地热资源调查及开发技术政策研究》

摘　　要：目前关中盆地开发利用的地热资源主要为新生界砂岩、砂砾岩孔隙裂隙型地热资源,开发利用层位主要为新近系热储层。地热资源赋存特征、地热资源开发有利区展布、地热资源量等与物源、古沉积环境密切相关,查明关中盆地新近系泥岩物源和古沉积环境特征,有利于指示同沉积时期砂岩物源和古沉积环境特征,对于关中盆地地热资源的开发利用重点层位确定、有利区预测及资源量计算具有指导意义。沉积岩中的元素地球化学特征记录了重要物源和沉积环境信息。依据关中盆地新近系泥岩岩心样品主量、微量和稀土元素特征对物源和沉积环境进行了综合研究,研究结果表明:关中盆地新近系泥岩的源区构造背景主要为活动大陆边缘,源岩主要为关中盆地南缘太白岩体正长花岗岩、华山岩体黑云母二长花岗岩,含有一定的中—基性火成岩;化学蚀变指数(CIA)介于61.34~76.78之间,平均值为70.78,反映新近系泥岩经历了中等程度风化作用,指示高陵群和蓝田-灞河组沉积期处于暖湿气候环境,张家坡组沉积期气候发生了转型,由暖湿气候转变为冷干气候;地球化学指标综合反映,新近系泥岩沉积期主要处于还原环境,水体古盐度整体表现为淡水、半咸水环境。At present,the geothermal resources developed and utilized in the Guanzhong Basin are mainly Cenozoic sandstone andglutenite pore−fissure geothermal resources.The development and utilization horizons are mainly Neogene thermal reservoirs.Theoccurrence characteristics of geothermal resources,the distribution of favorable areas for geothermal resources development,and theamount of geothermal resources are closely related to the provenance and paleosedimentary environment.Identifying the characteristicsof Neogene mudstone provenance and paleosedimentary environment is conducive to indicating the characteristics of sandstoneprovenance and paleosedimentary environment in the same sedimentary period.It has practical guiding significance for thedetermination of key horizons for the development and utilization of geothermal resources in the Guanzhong Basin,the prediction offavorable areas,and the calculation of resources.The geochemical characteristics of elements in sedimentary rocks record importantprovenance and sedimentary environment information.According to the characteristics of major,trace and rare earth elements ofNeogene mudstone core samples in Guanzhong Basin,the provenance and sedimentary environment were comprehensively studied.The results show that the tectonic background of the source area of Neogene mudstone in Guanzhong Basin is mainly active continentalmargin,and the source rocks are mainly syenogranite of Taibai rock mass and biotite monzonitic granite of Huashan rock mass in thesouthern margin of Guanzhong Basin,which contain some intermediate−basic igneous rocks.The chemical alteration index(CIA)ranges from 61.34 to 76.78,with an average value of 70.78,reflecting that the Neogene mudstone has experienced moderateweathering,indicating that the Gaoling Group and the Lantian−Bahe Formation were in a warm and humid climate during thedeposition period,and the Zhangjiapo Formation was deposited.The climate changed from warm and humid climate to cold and dryclimate;geochemical indicators comprehensiv

关 键 词：关中盆地 新近系 物源特征 古沉积环境 

分 类 号：P534.62[天文地球—古生物学与地层学] P595[天文地球—地质学]