地球学报2025，Vol.46Issue(4)：815-826,12.DOI:10.3975/cagsb.2024.112001
松嫩平原东南缘罗家窝棚组陆相红层的致色机理
Coloration Mechanism of Continental Red Bed in the Luojiawopeng Formation on the Southeastern Edge of the Songnen Plain
摘要
Abstract
Continental red beds are widely distributed worldwide and are considered to be the product of a special environment.However,research on the coloration of continental red beds in the Songnen Plain is insufficient.In this study,we considered the red bed of the Luojiawopeng Formation on the southeastern edge of the Songnen Plain as the research object;analyzed the geochemistry,petrology,and mineralogy of the collected samples;and explored the coloration mechanism and environmental background.Geochemical analysis of these samples showed that the Fe2O3 content of the Luojiawopeng Formation red bed was relatively high(6.76%),and whole-rock X-ray diffraction analysis,thin section identification,and diffuse reflection spectrum(DRS)analysis indicated that the content of hematite was extremely high,indicating that hematite is a red bed coloring mineral.The incomplete filling of hematite between grains in the thin-section analysis and the absence of local red bed provenance indicates that the hematite is of authigenic origin.High-resolution transmission electron microscopy(HRTEM)analysis showed that hematite adheres to the surface of the clay mineral kaolinite,which can serve as a transportation medium for iron oxides during migration.Therefore,it is believed that some hematite was transformed from other clay minerals,and the iron in the crystal lattice was leached,adsorbed,and oxidized on the surface of the kaolinite during its formation.The Fe2O3 content of this sample was higher than that of the other red beds,whereas the iron in the clay mineral lattice was limited.Combining CIA,A-CN-K ternary diagram,and UCC standardization,we concluded that the Luojiawopeng red bed is in the final stage of chemical weathering,while besides clay mineral source another part of iron is gradually accumulated as an immobile element.Luojiawopeng continental red bed of the coloration mineral is authigenic hematite,and the iron comes from the gradual accumulation of secondary clay mineral transformation,leaching,and chemical weathering.Based on the climatic significance of hematite and kaolinite,MAT,MAP,and the strong leaching of major elements,we infer that the Luojiawopeng red bed tends to be the product of alternating dry and wet weather under the warm and wet background of the East Asian summer monsoon.关键词
陆相红层/罗家窝棚组/致色矿物/赤铁矿/高岭石Key words
continental red bed/Luojiawopeng Formation/chromogenic mineral/hematite/kaolinite分类
天文与地球科学引用本文复制引用
刘晓萌,汪烨辉,吴鹏,孟杰,谢远云,李本仙,迟云平,康春国,孙磊,魏振宇,刘海金..松嫩平原东南缘罗家窝棚组陆相红层的致色机理[J].地球学报,2025,46(4):815-826,12.基金项目
本文由国家自然科学基金项目(编号:42171006)和黑龙江省自然科学基金项目(编号:ZD2023D003)联合资助. This study was supported by National Natural Science Foundation of China(No.42171006),and Natural Science Foundation of Heilongjiang Province(No.ZD2023D003). （编号:42171006）
