武汉阳逻化石木及砾石层研究进展

阳逻砾石层及所含的大量的化石木,在古植物学、长江中游的古环境和古长江的形成与演化研究中具有重要意义。随着1984年阳逻被子化石木的发现,武汉阳逻化石木和阳逻砾石层就一直为学者们所关注。先后发现的硅化木化石已达200余件。在阳逻化石木鉴定、植物分类、植物生态学和古环境研究方面,在阳逻砾石层的时代及年龄、成因和物源等方面,做了大量的研究,发表了许多重要成果。然而,在一些基础问题研究上还存在着明显的分歧。建议:(1)在化石木的来源和砾石层物源分析方面,开展系统的沉积学、岩石学、矿物学以及地球化学的综合研究;(2)通过综合地层学研究,即生物地层(植物化石组合)、岩石地层(长江中游岩石地层对比)、地貌地层(长江中游地貌对比)和年代地层的综合对比,重点尝试宇生核元素、化石自旋共振(ESR)等测年技术的应用,以查明化石木和砾石层的形成时代;(3)加强化石木和砂砾层环境信息深入挖掘和综合对比分析。在查明化石木植物树种的组合全貌的基础上,通过古植被类型的恢复,特别是应加强化石木的显微结构分析,通过观察其构造特征和生长轮(木轮、年轮)的宽窄等信息,分析其古气候环境。

PROGRESS IN RESEARCH ON FOSSIL WOODS AND GRAVELS AT YANGLUO, WUHAN

Gravels from Yangluo in Wuhan and large numbers of fossil woods contained in them are of important significance in research on the paleoenvironment along the middle reaches of the Yangtze River and the formation and evolution of ancient Yangtze River.With the discovery of angiospermous fossil woods in Yangluo,Wuhan in 1984,fossil woods and gravels in Yangluo,Wuhan,attracted great attention of scholars all the while.Fossil woods which were discovered successively total more than 200 pieces.A lot of research has been done and many achievements have been published concerning the identification,classification,plant bionomics and paleoenvironment of fossil woods,and the time of formation and the origin of gravels.However,there are obvious disputes in some basic problems.So this paper suggests: ⑴ integrated study should be done systemically about sedimentology,petrology,mineralogy and geochemistry as well as the origin of fossil woods and gravels.⑵ study should be done synthetically through stratigraphy,i.e.,bio-stratigraphy(plant fossil assemblage),rock strata(contrasting rock strata in the middle reaches of the Yangtze River),physiognomy strata(contrasting physiognomy in the middle reaches of the Yangtze River) and chronological strata,some dating methods such as Cosmogenic Element and ESR should be applied firstly;⑶ deep-going investigations should be conducted to develop environmental information,and contrasting and analysis should generally be strengthened of fossil woods and gravels.On the basis of disclosing the assemblage of fossil woods,the paleoenvironment should be studied through restoring these age-old plant types,especially strengthening the analysis of microstructure of fossil woods in terms of their structure features and growth rings(ring and annual ring).