成都理工大学学报（自然科学版）2025，Vol.52Issue(4)：704-721,18.DOI:10.12474/cdlgzrkx.2024061205
沉积分异对页岩有机质富集的控制机理——以川东北地区上二叠统为例
Control mechanisms of sedimentary differentiation on organic matter accumulation in shale:a case study of the Upper Permian,northeastern Sichuan Basin
摘要
Abstract
To reveal the differences in sedimentary environments and organic matter accumulation mechanisms of different shale lithofacies in the upper Permian in the eastern and northern Sichuan Basin,43 cores from wells DY1,FT1,DT2,and JT1 were observed using thin section and scanning electron microscopy,X-ray diffraction testing,and major and trace element analysis.It is concluded that the tectonic background of shale provenance was a continental island arc with an andesitic island arc provenance.Four shale lithofacies assemblages with 12 lithofacies developed in the study area.Siliceous shales were controlled by the high paleo-productivity and excellent preservation conditions in semi-humid and semiarid climates(high sedimentation rate of 1.5～3.0 cm/kyr and an anoxic to euxinic restricted water environment),resulting in the highest total organic content(TOC;2.01%～14.50%).Calcareous shales were controlled by lower paleo-productivity and good preservation conditions in semiarid to arid climates(high sedimentation rate,suboxic to anoxic and moderately restricted environment,and low chemical weathering intensity),leading to a high TOC(2.15%～13.90%).Clay shales were mainly controlled by higher paleo-productivity in humid and warm climates and poor preservation conditions(oxic to suboxic environment,high terrestrial input,and high chemical weathering intensity),resulting in a low TOC(0.38%～4.41%).Mixed shales were controlled by lower paleo-productivity and poor preservation conditions in humid to semi-humid climates(suboxic restricted environment,low sedimentation rate of 0.9～1.5 cm/kyr,and high terrestrial input),with the lowest TOC(0.20%～2.33%).The TOC of shales deposited in the deep-water shelf(2.15%～15.50%)are higher than those of shales deposited in the shallow water region(0.38%～4.41%).In summary,the shales deposited in the deep-water shelf have a high abundance and good types of organic matter.The siliceous shales are the most favorable for shale gas exploration and development.The clay shales deposited in shallow water have a high abundance of organic matter,which may become a promising field of shale gas exploration and development in the future.关键词
四川盆地/开江—梁平海槽/页岩岩相/主微量元素/有机质富集Key words
Sichuan Basin/Kaijiang-Liangping trough/shale lithofacies/major and trace elements/organic matter accumulation分类
能源科技引用本文复制引用
GU Tianfu,CHEN Shijia,SUN Haofei,NI Shuai,LU Jungang,LI Yong,MOU Feisheng,YUAN Lexin,LI Jiaming..沉积分异对页岩有机质富集的控制机理——以川东北地区上二叠统为例[J].成都理工大学学报（自然科学版）,2025,52(4):704-721,18.基金项目
国家自然科学基金重点项目(42230807) （42230807）
福建省教育厅2021年度中青年教师教育科研项目(JAT210031). （JAT210031）
