华北盆地太原组古水深古氧相的遗迹化石响应特征及演变规律研究

Based on the detailed study of ichnofossils and geochemical analysis in marine and terrestrial deposits of the Upper Carboniferous - Lower Permian Taiyuan Formation within the North China basin, this project tries to find out the types and their distribution characteristics of the ichnoassemblages and ichnofabrics in different beds of this Formation, and to analyze the microcomponents and origin of different color burrow fillings of ichnofossils (especially, the Zoophycos) in different sedimentary environments, substrate nature and tiering within the stratum, combining the analysis of microelements, carbon and oxygen isotopes, further to explore the characteristics of ichnoassemblages and ichnofabrics responding to palaeo-water depths and palaeo-oxygenation phase and confirm the indicator of ichnofossils of fine region correlation analysis in the stratum, ore beds and deposit environments, and then, to discuss the change feature of sea-level and ichnofossil evolution law of palaeo-water depths and palaeo-oxygenation phase. This research results will be beneficial to promote the development and progress of Chinese ichnology, sedimentology and other relate disciplines and catch up with advanced level in the world, meanwhile, may also provide the theoretical guidance to accurately analyze the sedimentary history of the North China basin and to finely correlate the stratum in region, and then can be applied effectively towards the better exploration and development of coal resource, especially, coal measure gas including coalbed methane, shale gas and compact sandstone gas in this study area, and put forward scientific basis in ichnology, sedimentology and stratigraphy.

通过对华北盆地上石炭统—下二叠统太原组典型剖面海陆交互相沉积中生物遗迹化石的精细研究与地化分析，试图查明太原组不同岩层中生物遗迹组合与组构类型及其分布特征，揭示不同沉积环境、底层性质和遗迹阶层中遗迹化石（尤其是动藻迹）潜穴不同颜色充填物的显微组分及成因，结合微量元素、碳氧同位素等特征分析，探索太原组中遗迹组合、组构与古水深和古氧相的响应特征，从而确定区域地层、矿层及沉积环境精细对比的遗迹化石指示标志，进而阐述太原组沉积期海平面的变化特征与古水深和古氧相的遗迹化石演变规律。该项研究将有利于促进整个遗迹学与沉积学和相关学科的发展和进步，使我国在该领域研究赶上世界先进水平，同时在应用上将对精准分析华北盆地太原组的沉积演化史与地层的精细对比提供理论指导，进而为该研究区太原组的煤炭资源、尤其是煤系气（包括煤层气、页岩气和致密砂岩气）的高效勘探和开发提供遗迹学、沉积学和地层学方面的科学依据。

本项目通过对华北盆地上石炭统—下二叠统太原组典型剖面海陆交互相沉积中生物遗迹化石的精细研究与地化分析，取得了以下主要成果：①查明了太原组碳酸岩中的遗迹化石组成、产状及时空分布规律；②结合部分遗迹化石及宿主岩中主微量元素和碳同位素的测试分析，划分出三种不同水深的遗迹化石组合类型，建立了不同遗迹组合与古水深变化的响应关系。在此基础上，确定了区域地层对比标志并论述了研究区海侵和海退演化规律。研究认为，焦作地区太原组沉积期经历了3次较大的海侵，豫西禹州、山西附城和太原西山分别经历了2次较大的海侵。在海侵过程中，最先接受海侵的地区为焦作，其次为禹州和附城，最后是太原西山。随着盆地南北的造山运动，华北盆地逐渐抬升，海水先从太原西山退出，然后是附城和禹州，最后是焦作。华北盆地太原组在发生最大海侵时，均发育代表水体较深的Nereites-Chondrites遗迹化石组合；③基于遗迹化石的组成、产状、分布及其宿主岩的沉积特征分析，结合不同遗迹化石充填物及其宿主岩的铁组分、微量元素的测试分析，建立了常氧相、次氧相、贫氧相、厌氧相4种类型的遗迹组合，并提出了研究区太原组古氧相的垂向演化规律。本项目的研究对恢复华北盆地晚古生代的古环境、海进和海退变化规律、并判识成矿的沉积背景和地层的精细对比具有重要的理论意义和实用价值。