摘要
"雪球事件"以来,早期生命呈现多层次、大规模的加速演化,到寒武纪前夕,生命大爆发达到高潮;在生命剧烈演替的同时,地球环境标志也发生着响应,碳同位素剧烈漂移,并且与各个生命演化节点相对应。但是在划分最重要的地质界线,埃迪卡拉(震旦)系——寒武系界线及界线层型和点位("金钉子",GSSP)确立的问题上迄今仍存在着较大的分歧,以遗迹化石Treptichnus pedum作为该GSSP的标志化石,因其跨系、跨阶产出,生物延限长,因而在全球的生物地层划分对比中(特别在西伯利亚和中国华南地区)一直质疑声不断,而且以遗迹化石作为标志化石本身也具有一定的缺陷。中国华南地区两类古老的宏体化石——矿化管状的Cloudina和条带状的Shaanxilithes在全球范围内可以很好的对比,并且这两种实体化石的出现都对应着碳同位素的明显正漂移。本文通过研究华南震旦系顶部化石带的地层分布和地理分布,综合分析了其时空分布特点和系统演化意义,深入探讨了Cloudina和Shaanxilithes作为寒武系底界标志化石所具备的潜力,对埃迪卡拉(震旦)纪—寒武纪地层界线划分和层型选择提出了更为理想的标准。
Since the “Snowball Event”,the early life has presented a multi-level,massive evolution,and reached its climax before the eve of the Cambrian.Accompanied the dramatic succession of life,the environment sign of the Earth changed and carbon isotope also shifted dramatically,both of which corresponded to the each stage of life succession.However,a big difference still occurs in the division of the most important geological boundaries,Precambrian-Cambrian stratotype section and point (“Golden Nail”,GSSP).Treptichnus pedum as a marker fossil of the GSSP has been questioned constantly in the global biostratigraphic division (especially in Siberia and South China),partially due to the fact that remains of trace fossils as a symbol also has certain defects.The earliest skeletal fossil Cloudina and the body fossil Shaanxilithes in South China can be well compared on a global scale,and the appearance of these two fossils corresponds to significant positive excursions of carbon isotope.By studying the stratigraphic distribution and geographical distribution characteristics of the fossil zone,this paper analyzes the spatiotemporal features and evolutional significance of the system,and discusses the potentials of Cloudina and Shaanxilithe as markers of Cambrian bottom.Finally,a more ideal standard is proposed to determine the Precambrian-Cambrian boundary.
作者
顾鹏
钟玲
张国栋
宋思存
唐烽
凌茂前
高林志
GU Peng;ZHONG Ling;ZHANG Guodong;SONG Sicun;TANG Feng;LING Maoqian;GAO Linzhi(Insititute of Geology,Chinese Academy of Geological Science,Beijing ,100037,China;Sichuan Museum,Chengdu,Chengdu,610071,Sichuan,China;Sichuan Geological Prospecting Bureau 207Teams,Leshan,614000,Sichuan,China;School of Earth Sciences and Engineering,Nanjing University,Nanjing,210023,Jiangsu,China)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2018年第3期449-465,共17页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号41572024)
中国地质科学院地质研究所基本科研业务费项目(编号YYWF201602)资助的成果.
