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若尔盖高原全新世气候序列的类脂分子化石记录

ISSN号：1001-7410
期刊名称：《第四纪研究》
时间：0
分类：P534.632[天文地球—第四纪地质学;天文地球—古生物学与地层学;天文地球—地质学] P593[天文地球—地球化学;天文地球—地质学]
作者机构：[1]西北大学地质学系大陆动力学国家重点实验室,西安710069, [2]中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,西安710075, [3]中国地质大学地球科学学院,武汉430074
相关基金：国家自然科学基金项目（批准号：40531003,40121303和40523002）和国家重点基础研究发展规划项目（批准号：2004CB720200）资助,致谢中国地质大学（武汉）湖北省地球表层系统开放实验室（GC/MS）对实验工作给予了极大支持,笔者深表感谢.

关键词：若尔盖高原, 全新世, 类脂分子化石, 气候序列, the Zoige Plateau, the Holocene, lipid molecular fossil, climatic series

中文摘要：

基于可靠的年代标尺，结合青藏高原泥炭沉积剖面的有机碳、孢粉等相关资料，首次在该区利用类脂分子化石指标建立了全新世以来的气候与环境演化序列。结果表明，正构烷烃、脂肪酸和脂肪醇等类脂分子化石指标存有意义的规律性变化。其中，反映低等菌藻生物和高等植物相对变化的轻组分与重组分之比L／H以及平均碳链长度ACL具有很好的古气候意义，即L／H高，ACL低，指示气候偏暖湿；L／H低，ACL高，指示气候偏干冷。各个类脂分子化石指标记录的气候信息在细节上具有一定的差异，可能是不同类脂物分子的地球化学行为和生物组成结构的不同以及对气候因素温湿组合变化响应各异的体现。同时，也较好地揭示了类脂分子化石具有自己的敏感性，在细节上较传统的有机碳指标在记录气候信息上更为敏感。该研究进一步突出了这些泥炭类脂分子化石在第四纪研究中的重要地位和应用潜力。

英文摘要：

The research area is located on a gradually rising plateau （the Zoige-Hongyuan Plateau） facing the north slope of the Tibetan Plateau. The peat swamp sampling site is in Hongyuan County, 2km southeast of the township, with an altitude of 3505m（ a. s. 1. ）. The core is 4.5m long and sampled at lcm intervals. This peat sedimentary sequence was systematically investigated by lipid molecular stratigraphy by gas chromatography-mass spectrometer （GC-MS）. A variety of molecular fossils are found in this peat profile, including n-alkanes, n-alkanols, n-fatty acids and so on. The n-alkanes are ranged from C15 - C35, having a maximum at C31. A bimodal distribution of n-fatty acids from C10 to C26 was observed, maximizing at C16 and C22 or C24, The alkanols from C12 to C28 also display a bimodal distribution, maximizing at C16 and C22or C24. Higher plants are the predominant source of the n-alkane compositions. The distribution patterns of n-fatty acids and n-alkanols indicate a mixed input from higher plants, algae, and microorganisms. Based on the establishment of a reliable AMS dating of the high resolution peat core, we have been able to establish climate and environment change series of the Zoigg Plateau using the distribution patterns of n- alkanes, n-alkanols, and n-fatty acids during the Holocene, together with the use of total organic carbon content, pollen assemblages and so on in the peat sequence. The results confirm that n-alkanes, n-fatty acids and n-alkanols proxies bear significant climate information. Of importance in paleoclimate reconstruction are the ratios of low molecular numbered and high molecular numbered molecule fossils （L/H） and average carbon chain length （ACL） representative of the relative abundance between microorganisms and higher plants. The higher L/H, the lower ACL, the warmer-wetter the climate; while on the contrary, the lower L/H, the higher ACL, the colder-drier the climate. These molecular fossil proxies together with total organic carbon content reveal a successi

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