中国东北二叠纪安加拉植物群演替

Based on the Angara fossil plants data, the terrestrial Permian chronostratigraphic framework will be established under the control of marine and marine-terrestrial transitional strata, and isotopic dating of volcanic rocks in northeastern China. Furthermore, through systematic identification of fossil plants (including pollen, spores and algae) and careful studies of their biostratigraphic characters, a series of fossil plants assemblages will be established in ascending order. This would prompt us to ascertain the time spans of some key taxa (on the level of species and genera) and the procedure of vegetative succession. On the bases of carbon isotope analysis of plant remains and kerogen, bivalve shells, the Permian organic carbon isotopic excursion curve will be drawn from the terrestrial strata in northeastern China and used for discussing the influences of atmospheric carbon dioxide on the fossil plants and their feedback. Finally, in the middle and high latitude of Pangea, the response of Angara plants to Permian dramatic climatic changes from the ice-house climate to hot-house climate will be discerned in the carbon cycle between land plants and atmosphere, especially the most important role the terrestrial plants played and the strategies of the plants faced the climatic crisis. This will be a sole case in the earth history to reveal the multi-factor coupling mechanism of climatic changes from ice-house to hot-house, and to provide geological implication for facing the global warming in the future.

充分利用我国东北二叠纪安加拉植物化石资料，将其纳入由海相、海陆交互相地层和火山岩测年所控制的二叠纪年代地层格架。在此基础上，通过对植物（含孢粉和藻类）化石的分类学和生物地层学深入研究，建立东北地区二叠纪安加拉植物组合序列，并查明关键分类群的时代分布和演替规程；通过对植物体、干酪根等的碳同位素分析，建立东北地区二叠纪陆相地层有机碳碳同位素漂移曲线，探讨陆生植物与大气之间的相互作用，最终识别二叠纪中高纬度区陆生植物-大气碳循环系统从冰室气候到温室气候剧变中的响应，特别是陆生植物在这一系统中的作用和对策，探讨地史时期气候变化中的多因素耦合作用机制，为应对当今全球变暖提供借鉴。

二叠纪是显生宙以来地质历史上气候变化非常剧烈的时期之一，冈瓦纳大陆的冰川直到早二叠世萨克马尔期才消融，经过早二叠世中晚期到中二叠世的冰室气候，到晚二叠世转变为温室气候，尤其到了二叠纪末期成为极热气候，导致全球生态系统崩溃，发生P-T大灭绝事件，地质历史从古生代更迭到中生代。因此，研究二叠纪的气候骤变为探讨第四纪冰期之后的气候变化并预测未来提供重要的也是唯一的地质历史借鉴。本项目将我国东北地区的安加拉植物群作为主要的气候变化载体，发挥中高纬度区植物未遭受二叠纪干旱气候带迁移影响而植物化石记录较完整的优势，从植物群演替和植物组合变化的角度来探讨陆生植物从冰室气候到极热气候转变中的响应，认识化石植物在气候变化时的对策，从深层次理解GLB、P-T界线的内涵和本质。.项目实施中，课题组系统研究了我国东北及新疆等地的石炭-二叠纪安加拉植物群，自下而上将我国东北二叠纪安加拉植物群划分为Asselian期、Sakmarian期、Artinskian-Kugurian期、Rodian-Wordian期、Capitanian期的、Wuchiapingian期、Changxingian期7个植物组合。从属种变化探讨了其间的差异，查明了演替的细节和事实，并将其纳入全球气候变化框架下。为此，课题组采用综合地层学方法，在海相化石（牙形刺）为主体的地层格架下，开展了大量火山岩年代学测试，建立起了东北地区二叠纪年代地层格架。在此基础上，总结出安加拉植物群二叠纪演替的四大规律，即：早二叠世的复苏和繁盛，中二叠世的萧条，晚二叠世初期的大爆发、晚二叠世晚期的大混生。由此反映出中高纬度区二叠纪气候变化由早二叠世Asselian-Sakmarian期的温凉气候、Artinskian-Kugurian期的温热气候、Rodian-Wordian期的温凉气候、Capitanian期的寒冷气候、Wuchiapingian期的温暖气候、Changxingian期的湿热气候。这一全球性变化在安加拉植物群演替中得到证实。