三峡地区埃迪卡拉纪Tianzhushania演化及生物地层意义

Large acanthomorphic acritarch Tianzhushania spinosa often occurred in the member II of Doushantuo Formation of South China. It has a distinct morphology and a large amount of number and is yielded in a relatively stable stratigraphic interval. Its phylogenetic affinity and biostratigraphic implications have drawn great world-wide attention from palaeontologists. Several new species, morphologically similar to Tianzhushania spinosa, are found in the member II of Doushantuo Formation at Jinianbei section that is located in the southern flank of Huangling anticline in the Yangtze Gorges area. They occur above the stratigraphic range of T. spinosa. The new species are also found in the member II of Doushantuo Formation at Jiuqunao, Wanjiaping and Qinglinkou sections that are located in the western and southwestern flank of Huangling anticline. Moreover, Tianzhushania spinosa roughly disappeared while the new species occurred. It shows that the new species occurred in a stable stratigraphic interval with a relatively wide geographic distribution. The new species showed a high morphological similarity and occurred in close stratigraphic intervals to T. spinosa, which indicates a possible relationship of evolution among them. Aiming at these problems, we need to carry out a detailed palaeontological and biostratigraphical study on the member II of Doushantuo Formation at the four sections mentioned above. Emphasis will be laid on the systematic palaeontology and evolution of Tianzhushania spinosa and the new species that are morphologically similar to T. spinosa, which would promote the Ediacaran biostratigraphic division.

大型具刺疑源类Tianzhushania spinosa在华南陡山沱组二段中最为常见，形态独特、数量大、层位相对稳定，其生物学属性与生物地层学意义倍受国内外学者关注。近来，申请者在对三峡黄陵背斜南翼纪念碑剖面陡山沱组二段的工作中，发现了一些形态相似于T. spinosa、但出现层位明显高于T. spinosa的化石新类型。前期工作在黄陵背斜西翼及西南翼的九曲脑、万家坪、青林口剖面陡山沱组二段也发现该化石新类型，当这些新类型出现时，T. spinosa基本消失，反映该类型地理分布相对广泛、层位稳定，有望成为生物地层划分的标志性分子。新类型与T. spinosa形态相似、出现层位相近，暗示它们之间一定的演化关系。针对上述问题，课题拟在上述四条剖面陡山沱组二段开展详细的系统古生物学与生物地层学研究，重点对T. spinosa及形态相似的新类型开展系统古生物学与演化学研究，从而进行生物地层的细划。

三峡黄陵背斜及其周缘地区埃迪卡拉系陡山沱组产出了丰富多样的具刺疑源类和多细胞藻类等微体化石，其亲缘关系、生物演化学与生物地层意义倍受学者关注。本项目在华南三峡和张家界地区开展详细的系统古生物学与生物地层学、演化生物学、化石埋藏学工作，取得了一些重要的研究进展，突出表现在以下几个方面：1）在三峡黄陵背斜西翼地区埃迪卡拉系陡山沱组发现Tianzhushania属及其形态相似属种和丰富的多细胞藻类微体化石，为完善三峡地区以及国际埃迪卡拉纪生物地层序列提供了新的依据，多细胞藻类为“雪球地球”冰期结束之后海洋生态系统的恢复奠定了良好的基础。2）在华南深水斜坡相区埃迪卡拉系陡山沱组发现可对比于经典研究地区（三峡地区）的具刺疑源类微体化石，为生物地层学研究与区域地层对比提供了新的古生物数据；3）首次在扬子板块发现了以往仅在塔里木板块分布的寒武纪最早期疑源类微体化石Yurtusia uniformis，膜壳内含多个子细胞，确定其与现代绿藻中的共球藻纲具有密切的生物学亲缘关系；4）通过激光拉曼光谱分析，解释埃迪卡拉纪薄层燧石条带的成因及其内含微体化石的埋藏学特征，重建了燧石条带中微体化石的保存过程。在项目执行期间，以第一作者身份已发表学术论文4篇，其中国际SCI期刊论文2篇。