华南石炭系杜内阶–维宪阶高精度有孔虫生物地层序列及有孔虫动物群多样性演变

High-resolution biostratigraphy subdivision and correlation is the reserch foundation of biological evolution events. Foraminifers were very abundant, widely distributed, and had high diversities and evolutionary rates in the Carboniferous. There have 15 to 16 foraminiferal zones in the Tournaisian–Visean (Carboniferous) from the typical areas of the word. Moreover, the Tournaisian–Visean boundary is defined by the FAD of the benthic foraminifer Eoparastaffella simplex, within the Eoparastaffella ovalis–E. simplex evolutionary lineage. Foraminifers have special significance for division of the shallow-water facies Carboniferous strata, because of the low-resolution biostratigraphy of macrofossils and relatively small amounts of conodonts in this facies. There have the best Tournaisian–Visean strata in the South China, and the Global Stratotype Section and Point (GSSP) for the base of the Visean Stage has been defined here. But, there have a low-resolution Tournaisian–Visean foraminiferal biostratigraphy subdivision and some problems. Therefore, this project will focus on the establishment of a high-resolution Tournaisian–Visean foraminiferal biostratigraphic succession in the South China based on the detailed study of foraminifers from several Mississippian sections of Guangxi, Guizhou, Hunan and Yunnan, their taxonomy and their global correlations. We try to make the new foraminiferal succession becaming a Eurasian standard successon for subdivision and correlation of the Tournaisian–Visean. Moreover, we will establish a Tournaisian–Visean foraminiferal diversity curve of South China and study the biodiversity pattern based on our new high-resolution foraminiferal biostratigraphic succession.

高精度的生物地层划分对比是探讨全球生物演化事件的基础。对于广泛分布的浅水相石炭系，大化石划分对比精度较低，牙形石在浅水相区又不发育，而有孔虫则非常发育。在国际上一些研究程度较高的地区，石炭系杜内阶–维宪阶可划分15–16个有孔虫带，包括全球维宪阶的底界也是用有孔虫定义的。因此，有孔虫对于石炭系划分对比极为重要。华南地区拥有全球发育最好的杜内期-维宪期地层，杜内阶-维宪阶界线的“金钉子”就建立于此。但华南杜内阶–维宪阶有孔虫生物地层的划分精度相对还较低，存在很多问题。本项目旨在通过对华南多条石炭系密西西比亚系剖面有孔虫的系统研究，建立高精度的华南石炭系杜内阶-维宪阶有孔虫生物地层序列，并与全球其他典型地区进行精确有效对比，力争使之成为欧亚普遍适用的有孔虫生物地层划分方案。进而以新建的高精度生物地层为时间格架，研究华南杜内期-维宪期有孔虫多样性变化并探讨其演化模式。

探讨重要的地质事件需要一个精确的等时格架，有孔虫是划分对比石炭系的关键古生物门类之一。本项目对华南多条石炭系密西西比亚系杜内阶-谢尔普霍夫阶剖面开展了有孔虫系统古生物学、生物地层学及多样性研究。通过本项目研究，在华南发现了大量的石炭纪早期有孔虫，丰富了这一时期的有孔虫动物群面貌；系统建立和厘定了华南密西西比亚系的高精度有孔虫生物地层序列，共计19个化石带，其中杜内阶9个，分别为：Bisphaera-Earlandia带、Chernyshinella glomiformis带、Palaeospiroplectammina tchernyshinensis带、Tuberendothyra带、Eblanaia带、Spinoendothyra带、Dainella带、Endospiroplectammina venusta/conili 带、Eoparastaffella rotunda 带；维宪阶7个，分别为：Eoparastaffella simplex 带、Viseidiscus / Planoarchaediscus带、Paraarchaediscus带、Pojarkovella nibelis带、Koskinotextularia带、Bradyina带、Janischewskina带；谢尔普霍夫阶3个，分别为：Plectomillerella tortula带、Eostaffellina paraprotvae带、Monotaxinoides transitorius带；这些化石带在欧亚地区能够进行很好地对比；初步勾勒出了密西西比亚纪有孔虫的多样性演变趋势；给出了中国区域性阶—上司阶底界的有孔虫定义，即以有孔虫Bradyina的首现作为识别上司阶底界的标志，并将上司阶与西欧的Warnantian亚阶的中上部和俄罗斯的Aleksinian亚阶-Venevian亚阶对比，对应国际维宪阶上部，为全球石炭系年代地层对比提供了可靠的化石依据。