摘要
为明确咸化湖盆沉积环境下混合沉积的基本特征和控制因素,以柴达木盆地古近系下干柴沟组为例,采用区域地质资料及录井资料分析、岩芯观察描述、室内样品分析等方法,对混合沉积的岩石矿物组成、层系组合特征、成因类型进行研究的基础上,研究混合沉积的分布模式,并分析其形成主控因素.认为湖相混合沉积具有多组分混杂、多类型叠置的特点,在相对浅水的湖相环境,物源输入及气候是控制混合沉积的主要因素.研究结果表明:研究区混合沉积以陆源碎屑(质量分数平均为40.93%)、碳酸盐(质量分数平均为44.82%)、盐类矿物(质量分数平均为7.91%)为主要成分.混合沉积以组构内泥质与碳酸盐的混合为主,同时发育薄层状的细碎屑与碳酸盐互层、盐类矿物与陆源碎屑的互层,另外还存在藻类(藻纹层、藻团块)与陆源碎屑的混合沉积.从成因类型上将混合沉积划分为渐变式混合沉积、突变式混合沉积(突变Ⅰ型、突变Ⅱ型)及原地混合沉积,其中渐变式混合沉积所占比例为80%~85%,原地混合沉积主要为藻灰(云)岩类与陆源碎屑的混合,约占8%~10%,突变混合沉积中的突变Ⅰ型约占混合沉积的5%~8%.滨浅湖区为互层混合沉积的主要发育相带,组构内混合沉积主要发育于半深湖相,藻类混合沉积主要发育于浅湖滩坝及水下隆起.古地貌通过影响物源供给及沉积水动力条件来控制混合沉积的发育;不同水体深度的化学条件与沉积物差异导致混合沉积的分布存在差异,另外,柴达木盆地古近纪为欠补偿沉积,持续的气候干旱,造成了广泛的盐类矿物沉积.
To deepen the understanding of the basic characteristics and controlling factors of mixed sediments in saline lakes,this paper takes the mixed sediments of lower Ganchaigou formation of Paleogene in the western Qaidam Basin as an example.The distribution pattern and forming dominant factors of mixed sediments were studied based on the analysis of rock mineral composition,layer combination characteristics and cause type.The method used in this study included regional geological data analysis,logging data analysis,core observation and description and indoor sample analysis.It was considered that the lacustrine mixed sediments had the characteristics of mixed multi-components and overlapped multi-types,and the input of source and climate in the lacustrine environment of relatively shallow water were the main factors controlling the mixed sediments.The results showed that the mineral composition of mixed sediments was mainly terrigenous debris(average mass fraction was 40.93%),carbonate(average mass fraction was 44.82%)and salt minerals(average mass fraction was 7.91%).The composition types of mixed sediments were mainly the mix of mud and carbonate within the fabric,thin interlayer of fine debris and carbonate,thin interlayer of fine debris and salt minerals,and the mix of algae(algal layer and algae clumps)and terrigenous debris.The cause types of mixed sediments included gradually changed type,mutational changed type(typeⅠand typeⅡ)and an original position type.The proportion of gradually changed mixed sediments was 80%—85%.Original position mixed sediments was mainly the mix of algal limestone,algae dolomite and terrigenous debris,and its proportion was about 8%—10%.The typeⅠof mutational changed mixed sediments was about 5%—8%.Shallow lake was the main facies zone of thin interlayer mix deposition,semi-deep lake was the main facies zone of mix deposition within the fabric,and the beach and bar of shallow lake and underwater bulge were the main facies zone of mix deposition related to the algae.Paleot
作者
张世铭
张小军
王建功
张婷静
崔俊
王超
伏珏蓉
ZHANG Shiming;ZHANG Xiaojun;WANG Jiangong;ZHANG Tingjing;CUI Jun;WANG Chao;FU Juerong(Northwest Branch of Research Institute of Petroleum Exploration and Development,PetroChina,Lanzhou,Gansu 730020 China;Key Laboratory of Reservoir Description,PetroChina,Lanzhou,Gansu 730020,China;Exploration and Development Department of Qinghai Oilfield,PetroChina,Dunhuang,Gansu 736202,China)
出处
《中国矿业大学学报》
EI
CAS
CSCD
北大核心
2022年第1期160-173,共14页
Journal of China University of Mining & Technology
基金
国家重大科技专项(2016ZX05003-006)
中国石油重大科技专项(2016E-0101)。
