距今7000年来河南郑州西山遗址古代人类生存环境

对河南郑州西山遗址同期山麓洪积成因的自然沉积剖面样品的有机碳、炭屑含量、碳氮比值和孢粉进行了分析，根据其实验结果，结合平原地貌与物质组成特点，分析了该地区 7000aBP古代人类生存的气候与环境特征，得到如下结论：1）7300 aBP以来气候变化大约以2900aBP为界，在此之前以暖湿为主，当时当地的气候大体与今日的江淮地区的气候相当，台地上宜旱作，有机碳反映出暖湿期内至少存在5个干旱时段。到2900 aBP以近，气候旱化趋势明显，与当地现今气候接近。2）当地的地貌条件是洪积成因的向东向南倾斜的宽阔平原，虽有枯河穿过，因其具有冲沟性质而无泛滥之苦，又平原的组成物质下部是更新世洪积黄土层，顶部为全新世黄土层，很适合古代人类居住和进行旱作农业耕作活动3）以土地氮量供应不足为标准进行判断，至少在7 300 a BP前后这里已开始了旱作农业活动，这种判断与本地区以草本花粉为主的孢粉分析结果是吻合的。在炭屑浓度上，表现为早期D（炭屑长轴直径）＜50μ的具有n×102 片/ 厘米3，D＞50μ的只在近5000 aBP才断续出现，这种变化与耕作施肥技术的进步不无关系。

Living environment of ancient man since 7 000 a B.P.at Xishan Relic Site of Zhengzhou in Henan Province

Based on the analysis of organic carbon，charcoal pieces，pollen，and ratio of carbon and nitrogen from sediment profiles in flooded hill foot，and the features of topography and sediment materials at Xishan Relic Site of Zhengzhou，Henan Province，this paper presents changes of climate and living environment since 7 000 a BPin this area  The main results are as follows: (1) Since 7 300 aBP，two periods were divided Before about 2 900 a BP，the climate was warm and wet，similar to today's climate in Jianghuai regionDry land could be developed in higher platform under this climatic conditionThere were at least 5 drier stages during this warm and wet period from the analysis of content of organic carbon  The climate after 2900 a BP showed an obvious trend of arid which was similar to that of today in Zhengzhou(2) The topography in this region is a broad flooded plain with a southeast slope A gully like river，named Kuhe，passes through the plain but has less flooding The plain consists of the Pleistocene flooded loess in the lower layers and the Holocene loess in the upper layersSo at ancient time，people lived here and had dry land farming (3) According to the insufficient amount of nitrogen supply from farmland，dry land agriculture started at least from  about 7 300 a BPThis result is the same with the conclusion from pollen analysis，most of which was from grassAccording to the analysis of concentration of charcoal pieces，the concentration of pieces with the diameter of long axis less than 50μ was n×102 piece/cm3 for samples before 5 000 a BP，but for samples after 5000 a BP，most of the pieces had diameters larger than 50μThis change showed the development of tillage and fertilizer technologies