【作者】 李平华；

【导师】 黄春长；

【作者基本信息】 陕西师范大学 ， 自然地理学， 2002， 硕士

【摘要】 全新世是地球历史最新的一页，现代气候是全新世气候的延续和发展。最近二十多年来，国际国内的地学界都十分重视全新世的研究，深入了解和探讨全新世气候演变规律、各阶段气候特点、有关气候事件的性质和发生原因对认识现代气候形成、灾害发生规律以及预测未来气候具有实际的科学意义。 野外考察发现，位于周原地区的扶风县JYC剖面全新世两层古土壤的出现在关中地区具有区域代表性。该剖面发育连续、完整，其全新世土壤S₀分裂为两层：S₀¹和S₀²，其间夹有风成黄土层L_x。对该剖面从上而下每2cm间隔进行高密度采样，采得190块样品，进行分析研究。 粒度分析中各粒组含量在黄土剖面中的变化是衡量西北季风强度长期变化的代用指标；剖面中高分辨率的磁化率变化，描述了受东南季风变化控制的年降水量变化的尺度和幅度；全铁含量与成壤强度成正相关，与磁化率曲线具有相同的变化趋势；碳酸钙由于其易溶而在风化过程中变化明显，可以作为探索大气降水或湿润程度的指标；有机碳含量与黄土堆积之后的生物气候环境关系密切。本文采用上述五个气候代用指标对本研究剖面进行了分析测定，获取了较详尽的全新世高分辨率环境演变数据资料。 周原地区不仅是新石器革命的中心，而且是周文明的发祥地。其古文明是诞生和发展在黄土之上的，是与全新世地层同步发育起来的。全新是地层中包孕着人地关系演化的大量信息，人类史前文化在很大程度上受制于自然环境的变化。 本文根据野外考察和以上实验分析的结果，通过分析论证，总结了周原扶风地区全新世环境演变的基本规律，并对环境演化的社会响应问题进行了探讨，得出如下结论： （1）在11500-8500aB．P．的全新世早期，地层为过渡层L_t。为夏季风增强，冬季风减弱的转变时期。温度上升，降水增多。当时年均温由7℃左右逐渐上升至11℃左右，年均降水量由500mm以下上升至650mm左右。 （2）在8500-6000a B．P．，地层为古土壤S₀²，为全新世气候最适宜期。夏季风达到最大强度，降水显著增多，温湿的气候状况达到鼎盛。当时年均温可达13.5℃左右，降水量最高达750mm，高于现今150mm左右。这一时期周原仰韶文化繁荣发展。 （3）在6000-5000aB．P，地层为黄土L_x，是全新世中期的气候恶化期。这一时期夏季风减弱，冬季风增强，风成黄土堆积，降水减少。当地仰韶文化走向衰落。 N)在 5000千 00a B．P，地层为古土壤 S。‘，为温湿气候回返时期。气温回返上升，夏季风增强，冬季风减弱，降水量增多，成壤作用变强。龙山文化繁荣发展。 （5）3100a B．P．－现代，地层为黄土L和表土 MS，为气候再度恶化时期。夏季风减弱，冬季风增强，年均温下降至＊－12OC，降水量降至650nun以下。对应商末以来大量旱灾、尘暴记载。 （6）就周原地区来看，人类社会发展在很大程度上受制于环境的变化。在这个半干旱地区，温湿气候有利于原始农业的发展，从而促进了社会进步及人类文明的发展，而气候恶化影响了农业经济的发展，对社会进步及人类文明发展产生了不利影响。更多还原

【Abstract】 Some Holocene Loess profiles with several palaeosol layers have been found in Guan Zhong Basin. The layers of loess and palaeosol emerged alternately hi these profiles ,which revealed the environment change. Research has indicated that the climate in Holocene is unsteady. The profile in Jiangyangcun Site, Co.Fufeng of Zhouyuan region is studied in this paper, and it is situated at the east boundary of the archaeological site of the Qiyi city of the predynastic Zhou. Two layers of palaeosol have been contained in the stratum of Holocene in this profile.Field investigation and analysis of grain size, magnetic susceptibility, total Fe, TOC and CaCOs in the profile detailed the characteristics of climatic change during the last 11500 years:(1) 11500-8500a B.P., summer monsoon was stronger and winter monsoon weaker. Temperature went high graduately, at the same time, precipitation got much. During this period, temperature increased from 7癈 to about 11 癈, precipitation increased from under 500mm to 650mm.(2) 8500-6000a B.P., summer monsoon reached its maximum in the Holocene. Precipitation increased remarkably, it reached 750mm. The annual temperature reached about 13.5癈. In this period, Yangshao culture was prosperous.(3) 6000-5000a B.P., This is a period of climatic deterioration. Summer monsoon was weaker and winter monsoon stronger. Precipitation decreased, and eolian dust deposition was accelerated. Yangshao culture declined.(4) 5000-3 lOOa B.P., It got warmer and wetter, pedological process was dominant. Annual temperature and precipitation decreased. Longshan culture developed.(5)<3100a B.P., Climate deteriorated again. Summer monsoon was weaker and winter monsoon stronger. There were much riot in the end of Shang dynasty. Many documents of dust storm and aridity in Shang and Zhou dynasty are found.(6) The prehistoric culture was dominated by natural environment. The change of climate during Holocene in this region has a important impact on the social.更多还原