【作者】 解三平；

【导师】 孙柏年；

【作者基本信息】 兰州大学 ， 古生物学与地层学， 2007， 博士

【摘要】 滇西地处横断山南部，青藏高原东南缘，是我国现代植物最具多样性的地区之一，也是我国新生代植物化石保存最好的地区之一。研究保存于新近系中的植物化石，不仅可为植物的分类和演化提供材料，为认识和理解我国植物多样性的渊源提供实证；而且可以提取保存于化石记录中的古环境信息，重建滇西新生代全球降温背景下的古气候演化，认识晚新生代构造运动对该区的作用和影响。本文采用数值统计工具，对产于云南腾冲上新统的两类翅果化石进行了数值分类和分支分析。结果表明，类黄杞翅果化石可以分为4个类型，包括2个已知种和2个新种，它们分别是：Palaeocarya guangxiensis，Palaeocarya koreanica，Palaeocarya longialata sp．nov．和Palaeocarya yunnanensis sp．nov．。这些类黄杞化石与生长于东南亚和我国华南的现生黄杞属具有较多的相似性，具有较近的亲缘关系。黄杞族植物在我国从上新世到目前地理分布范围的变化，印证了晚新生代全球变冷趋势。对上新世槭属翅果化石的数值分类表明：所有标本可以划分成7个形态类型，分别为：Acer subpictum，Acer miofranchetii，Acer browni，Acer macrocarpium sp．nov．，Acer globicarpium sp．nov．，Acer tengchongense sp．nov．和Acer sp．。对其所做的分支分析表明：7个化石种具有形态上的多样性，处于不同的演化水平，某些化石种已经具有与现生槭属相当的进化水平。利用大量的被子植物叶片化石，基于叶相特征进行了单变量和多变量的古气候重建。结果显示：单变量方法得到的结果要高于多变量分析，气候与叶片多变量分析结果为：云南腾冲上新世年均温在17.16～17.68℃之间，热月平均温度在25～25.5℃之间，冷月平均温度在9.54-10.8℃之间，生长季月数在9.71～9.5之间；生长季降雨量在183.43～190.12cm之间，生长季平均月降雨量在22.24～23.05cm之间，3个连续最湿润月降雨量在89.21～91.78cm之间，3个连续最早月份降雨量在47.45～51.28cm之间，相对湿度在76.65～77.75之间，比湿度为10.74～10.79，热熵为318.4～319.7ki／kg。根据被子植物叶片的气孔指数和碳同位素组成对古大气CO₂浓度和植物古生理参数进行了定量重建．分析结果为：利用气孔方法重建的大气CO₂浓度变化趋势与古海洋有孔虫地球化学证据相一致，上新世早期大气CO₂浓度较高，超出当前水平：两种植物化石的碳同位素分馏值高于现存对应种，水分利用效率低于现存对应种，印证了上新世早期的气候比现在温暖湿润。气孔指数还表明，上新世晚期大气CO₂浓度较低，略低于目前水平。更多还原

【Abstract】 The west of Yunnan Province locates in the south of the Hengduan Mountains and southeast margin of the Qinghai-Tibet Plateau, where well-preserved plant fossils were sampled in the current research. West Yunnan is one of the best localities not only for modern plants diversified, but also for preservation of Cenozoic plant fossils. The present study on Neogene fossil plants can provide evidence for plant systematics and evolution, and furthermore, it may strengthen our knowledge about the origin of plant diversity in China. Moreover, we can also acquire the knowledge about paleoclimatic evolution and paleoenvironmental changes. Thereby, we can get the information about the influence of the Late Cenozoic movement on West Yunnan’s environment.The numerical taxonomy on Palaeocarya specimens suggests that four species were recognized, and they were assigned to Palaeocarya guangxiensis, Palaeocarya koreanica, Palaeocarya longialata sp. nov., and Palaeocarya yunnanensis sp.nov. These fossil species are much similar to Engelhardia species that now inhabit Southeast Asia and South China, and they may be close relatives. Engelhardieae species from the Pliocene to today moved southward or maintained at lower latitudes while the more northerly populations became extinct provides additional evidence that Neogene cooling affected the north/south latitudinal distributions of the Engelhardieae and many other plant species.The clustering based on morphological characters assign specimens of Acer fruits into seven types. They are Acer subpictum, Acer miofranchetii, Acer browni, Acer macrocarpium sp. nov., Acer globicarpium sp. nov., Acer tengchongense sp. nov., and Acer sp. The cladistic analysis showed that the fossil species of Acer much diversified in morphology and may be at different evolutional levels, even some species have evolved into comparative levels with certain extant Acer species.We also conduct paleoclimatic reconstruction based on the leaf physiognomy of angiosperm fossils with the methodology of univariate and multivariate statistics. The results demonstrated that the univariate analysis abtain a higher result than the multivariate method. The multivariate program （CLAMP） acquired the following climate values: mean annual temperature （MAT; 17.16～17.68℃）, warm month mean temperature （WMMT; 25～25.5℃）, cold month mean temperature （CMMT; 9.54～10.8℃）, length of the growing season （GRS; 9.71～9.5 months）, growing season precipitation （GSP; 183.43～190.12cm）, mean monthly growing season precipitation （MMGSP; 22.24～23.05cm）, precipitation during the three consecutive wettest months （3WET; 89.21～91.78cm）, precipitation during the three consecutive driest months （3DRY; 47.45～51.28cm）, relative humidity（RH, 76.65～77.75%）, specific humidity （SH, 10.74～10.79）, and Enthalpy （ENTHAL, 318.4～319.7 kj/kg）.We also investigated the stomatal indices and carbon isotope composition of fossil angiosperm leaves, and then calculated paleo-CO₂ level and phytophysiological parameters in Pliocene. The results show stoma-based paleo-CO₂ estimates is consistent with the independent evidence of geochemistry from marine foraminifera. The paleo-CO₂ level in Early Pliocene is higher than current levels. The carbon isotope discrimination of fossil plants is also higher than that of their nearest living relatives （NLRs）, whereas, water use efficiencies of the fossils is lower than that of their NLRs, which confirmed the climate of Early Pliocene was more humid and warmer than it is now. The stomatal data also demonstrate slightly lower Paleo-CO₂ concentration in the Late Pliocene than today.更多还原