华南古生代中期地层界面及其意义

This project aims to study the evolution of early Paleeozoic South China Block and the environment, and with the early land vascular plants, and focus the bed boundaries of middle Palaeozoic as the starting point . The features of early Palaeozoic tectonic are most distinct and controversial tectonic problems in the tectonic evolution of South China Block. The bed boundary of middle Palaeozoic (Silurian and overlying strata) is one of the important tectonic transformation beds in the geological history of South China continent. The bed boundary of middle Palaeozoic is characterized by most changes and complex, however, this boundary also is a boundary that is weaker than another in the study of South China Block; many key questions of this bed boundary are not clear and need to be solved in the moment. During this period, there was a major event of biological evolution, the plants successfully landed and occupied the different terrestrial ecosystems. The South China Block had the relatively stable terrestrial ecosystems, formed a series of both a strong inheritance, but also a significant place featuring floras. The studies of fossil plants have the important significance in the origin, distribution and evolution of the land plant plants...This project studies of strata, fossil plants and animals around this bed boundary based on the standards of the international stratigraphic subdivision and correlation; focuses on the strata around this boundary, and determines the precise geological times; is to integrate the numerical palaeogeographic atlas of 8 epochs by the database; is to mainly discuss the end times and evolution of Kwangsian orogeny, studies the origin and evolution of early land plants, and provides the reliable geological information and evidences in study of the tectonic of South China Block. The results of this project will lay a solid foundation for the realization of the tectonic evolution of South China Block in the Stratigraphy, Palaeontology, Palaeogeography and Sedimentary; and is looking forward to provide the credible geological records in study of the tectonic background and stratigraphies of the oil and gas reservoir and preservation.

本项目旨在研究华南陆块早古生代构造-环境演变过程和早期陆生维管植物的更替,拟以古生代中期界面地层研究为抓手。在华南陆块构造研究中, 早古生代构造属性最具特色和争议，关键是古生代中期地层界面特性。但是, 该界面变化大，复杂多样，是一个研究相对薄弱的界面。同时, 该时段发生了一次重大生物演化事件，植物成功登陆到占据不同陆地生态系统，在华南发育了一系列具很强继承性和明显地方特色的植物群，其研究将在植物的起源、分布和演化上具有重要意义。本项申请拟探究整个华南古生代中期地层界面特征，研究早古生代华南陆块东、西研究区古生物地层、沉积和古地理演变的异同，探讨“广西运动”结束的时间、演变进程、与陆生维管植物起源和早期演化的关联性；建立华南早古生代地层界面数据库, 集成华南古生代中期地层界面上、下地层8个时期的数字化古地理图集。本项目的研究将为华南大地构造演变进程的认识奠定坚实的古生物地层和沉积古地理基础.

华南古生代中期地层界面, 指早古生代地层与上覆地层之间的接触界面; 这是华南地质发展史上重要的构造转换界面之一, 综合研究其分布特征对探讨华南大地构造的演变, 特别是广西运动进程的研究具有独特的、 基础性的科学意义. 本项目根据华南14省及1直辖市、 115县的126条穿越该地层界面剖面的研究, 揭示出其界面上、 下地层的时空分布特征, 识别出华南古生代中期地层界面接触关系有3大类: 角度不整合、 平行不整合、整合; 并以该界面上、 下地层的时间和分布特征为依据, 划分为3个分布区. 在华南全区, 在大时间尺度上, 广西运动是一次长历程的地质作用, 体现在虽然各地发生、 发展、 结束时间和后续推进过程略有差异, 但大体的时间相近; 它最先发生于晚奥陶世珠江区, 到达扬子区的时间大约晚了10 Ma; 发展的高点在志留纪普里道利世早期; 结束的时间从早泥盆世洛赫考夫晚期开始, 呈现为一个由南向北、 由西向东的强力推进过程. 华南广西运动在不同地区具有不同的表现形式, 雪峰-九岭山以东和以南地区地质作用较为强烈, 界面为角度不整合, 体现了陆内造山运动的形式; 以西和以北地区地质作用相对平和, 界面为平行不整合, 以反复、 多幕的升降运动为特征. 广西运动的动力源问题甚为复杂, 本项目提出导致华南广西运动发生的动力源是多源和多方向的, 正是由于不同的块体从不同的方向大致在晚奥陶世凯迪期间对华夏块体的挤压作用, 广西运动在华南广大地区以不同的方式发生和推进。