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[摘要]
古海拔的定量重建在推演地球动力学模型、大气循环模式、古气候变化以及地球化学循环过程方面都具有十分重要的作用, 但是迄今为止在古植物学和古环境研究领域中古海拔的定量重建仍然存在许多难点。本文在介绍目前古海拔定量重建领域几种方法的基础上, 重点对植物叶片化石气孔参数及其应用与进展进行了讨论, 着重介绍: (1)如何利用植物叶片化石气孔参数法恢复古海拔; (2)方法实践过程中的误差来源与分析; (3)应用实例及展望。
[Key word]
[Abstract]
Quantitative estimation of palaeoelevation is of great significance for studying geodynamic models, atmospheric circulation patterns, climate changes and geochemical cycles of the geological history. In the field of palaeobotany and palaeoenviron-ment, there are still many difficulties to accomplish the quantitative reconstruction of palaeoelevation. Based on the brief in-troduction of several methods for palaeoelevation reconstruction (including palaeoelevation measurements based on the ve-sicular basalts, stable isotope composition and megafossil plants’ analysis), the application of stomatal parameters in fossil leaves as a proxy for palaeoelevation is discussed in this paper, with emphases on its application principles and superiority. Compared with macroscopic methods in the field of palaeobotany, using stomatal parameters in fossil leaves can be more precise and cover a wider time span, due to its almost unaffected by the discrepancies caused by the plants’ evolution. How-ever, there is no doubt that this method still has some deficiencies, such as the limitation of the directly applicable research objects and the necessities of further investigation of error analysis to broaden the fossil plants’ taxonomic applied range. This paper aims to introduce: (1) How to apply the stomatal parameters in fossil leaves to make quantitative reconstruction of palaeoelevation, emphatically discuss the method’s principle, restrictions of research objects’ selection, formula deduction and practical calculation procedures; (2) Discussion on the error sources from environmental factors during the process of prac-tice and analysis, including error sources from illumination intensity, temperature, gas exchange rate and calculation of pCO2 at sea level during the specific geological age, as well as the theory or methods of error reduction; (3) Brief introduction of the application examples for this method, discussion for case research localities in China, and prospect for the method that can be used as a positive approach for investigation of palaeoelevation in a more extensive time interval. We also discuss the potential research prospect of using this method to further verify the nature of the East China Plateau during the Late Meso-zoic, and deduce its history of structural evolution or its combination between the destruction of the North China Craton.
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