滇西腾冲地块二叠纪生物地层序列的建立和对比

Gondwana dispersion and Asia accretion are by far the most important geological events in the late Paleozoic, the complex dynamic processes of which remain far from being fully understood. Geological records on Gondwana-derived blocks in Tibet and Yunnan, SW China provide the basis, from which information about the paleogeographic development of Gondwana and Tethys may be extracted. Among these blocks, the Tengchong Block in western Yunnan has relatively been less studied and bears many uncertainties in terms of its Permian stratigraphy. .Although a general framework of Permian stratigraphic successions has been established after geological mapping in last century and some studies in recent years, the biostratigraphic study of the Permian System of the Tengchong Block needs to be further improved in many respects. For instance, the positions of fossil-bearing beds, the taxonomic composition of different faunas, and the fossil zonation in Permian stratigraphic successions are still not clear. Besides, the age of the highest Permian sediments remains unclear. It is, therefore, necessary to further the biostratigraphic study on various Permian fossil taxa by means of seeking new sections and fossil-bearing beds, clarifying faunal compositions and correlating biostratigraphic successions from different areas. This study would eventually establish a greatly enhanced synthetic Permian biostratigraphic sequence of the Tengchong Block. It will also provide significant biostratigraphic constraints on the tectonic and paleogeographic evolution of this block, and even that of the vast Tethyan realm.

冈瓦纳大陆的裂解与亚洲的增生是晚古生代以来的重大地质事件，我国的滇藏地区为解决这一地学难题提供了难能可贵的物质基础。然而，相对其它冈瓦纳裂解地块而言，腾冲地块的研究程度相对有些偏低。上世纪地质填图工作以及近年来一些学者的研究，初步建立了该地块二叠纪地层的格架，但在许多方面仍有较大的提升空间。如：腾冲地块二叠纪地层中不同层位有孔虫和腕足类化石的属种面貌为何？可建立哪些化石组合或化石带？该地块二叠纪沉积最高到什么层位？等问题还有待研究。因此，十分必要再前期研究基础上，深入开展各门类的古生物地层学工作，发现新剖面和新材料，确定化石产出层位以及不同层位的化石组成，最终建立和完善该地块二叠纪生物地层序列并进行区域综合对比。这将有望把腾冲地块二叠纪生物地层学的综合研究程度提高到一个新的水平，为探讨该地块二叠纪的构造位置、沉积环境和古地理演化，乃至为重建冈瓦纳北缘地区的构造演化提供新的生物地层学约束。

项目四年的工作基本上按计划执行，如期开展了野外工作、样品的分析测试、以及成果的总结和国际学术交流。在野外追索地层、发现新剖面和新化石材料、以及细致的门类古生物地层学工作的基础上，对腾冲地块的化石产出层位和化石组成面貌有的新的认识，使腾冲地块二叠纪生物地层序列及区域对比关系的精确程度有了进一步地提高。完成了项目原定任务，实现了预期目标。在国际学术刊物上发表了腾冲地块二叠纪地层综述一篇，腾冲地块筳类生物地层学一篇，作为对比研究的保山地块的筳类生物地层学及生物古地理两篇，保山地块二叠纪鲕粒碳酸盐岩岩石学及古地理古环境意义一篇。完成一部关于腾冲地块和保山地块晚石炭世―早二叠世孢粉生物地层学的博士学位论文，培养博士一名。