Conifer Fossils From The Cretaceous And Neogene In Eastern Zhejiang And Reconstruction Of Paleoenvironment

Fine microstructures of three fossil species,i.e.Pseudofrenelopsis papillosa (Chow and Tsao)and Pseudofrenelopsis parceramosa(Watson)collected from the Cretaceous deposits of Jingling,Xinchang County,Zhejiang Province as well as Cunninghamia lanceolata(Lamb.)Hook from the Neogene diatomite in Tiantai County,Zhejiang Province,are observed and researched in detail under the scaning electron microscope and light microscope in this dissertation.CO₂ concentration estimates(861～1047ppmv)for the late epoch of the early Cretaceous,based on stomatal indexes of fossil materials of P.parceramosa and its NLRs,indicate that the use of the Carboniferous standard is much more reliable in the reconstruction of atmospheric CO₂,and the species could be regarded as a sensitive environmental indicator.After studying the stomatal parameters in the lower cuticles of modern C lanceolata from four different places,we discover that they varied to some extent with different parts of the laminas,although the total variation is not great.Stomatal parameters in the middle part of the lamina are quite stable,especially for stomatal index.The cell wall in the upper cuticle is curved and the curve has something to do with the surrounding humidity positively.The correlation between the stomatal parameters and climatic zones shows that most data of the stomatal parameters from Xian(Shanxi Province),Wenxian(Gansu Province),Tiantai(Zhejiang Province)and Kunming(Yunnan Province),drop consistently in the same area of the plot(by excel), which also elucidates the fact that the stomatal parameters of C lanceolata from various climatic zones are extremely stable. The late Miocene(10.5Ma～)CO₂ concentration is reconstructed by the stomatal parameters of fossil C.lanceolata from the successive strata based on the stomatal ratio,and the increasing estimates with geologic time are 401,411,413 and 471 ppmv, respectively.Furthermore the Berner's carbon budget model is supplemented by the records in the present paper.But one of CO₂ concentration indexes,which are highly estimated by the stomatal ratio method,is beyond the Berner's error range and the situation could be caused by the larger standardization(×1.2).According to the study on leaf shapes and stomatal parameters of C.lanceolata and Metasequoia glyptostroboides,the late Miocene CO₂ concentration over time for 319,324,325 and 377ppmv is corrected based on the functional correlation between the stomatal parameters of Metasequoia glyptostroboides and CO₂ concentration.The response to atmospheric CO₂ concentration is similar between the two species,which promotes the exploration of quantitive CO₂ concentration estimates.Using the coexistence approach,the paleoclimate and paleo-altitude are reconstructed by the macrofossils from the late Miocene Xiananshan Formation, Zhejiang Province.The results are listed as following:paleo-altitude(500～1200m), mean annual temperature(9.91～19.74℃),cold month mean temperature(-3.20～5.19℃),warm month mean temperature(16.73～26.44℃),difference of temperature(18.31～30.68℃),the highest annual temperature(27.99～37.41℃)and the lowest annual temperature(6.56～-20.16℃).And also the study is helpful for an understanding of the paleoclimate in the Miocene of Zhejiang Province.