Abstract:

Foye Chi is a small lake developing in a cirque in the alpine belt of southern slope of Taibai Mountain which is the peak of the Qinling Mountain Range. A 70 cm deep pit was excavated on the desiccated floor of this lake and sediments were sampled from the pit’s wall. AMS 14C dating was performed for three samples from this sediment profile. For all the 56 samples, analysis of total organic carbon content (TOC) and carbon-nitrogen ratio (C/N) and measurements of low-frequency magnetic susceptibility (χ_lf) and anhysteretic remanent magnetization (ARM) were undertaken. So were analyses of particle-size and pollen. ARM/χ_lf was further calculated as well. A chronological framework was developed based on the dating results. Variations in TOC, C/N, χ_lf, ARM, ARM/χ_lf, mean particle-size and percentage of Quercus pollen of this sequence were interpreted and climatic and environmental changes occurring around Foye Chi since 5520 aBP were so preliminarily inferred. The climate and environment were generally cold and arid during 5520-3800 aBP and the coldest and driest during 5100-4300 aBP. During 3800-2300 aBP, the climate and environment have turned to be warm and humid. The climate and environment were even wetter during 2300-1300 aBP and warmer during 1300-700 aBP which might be the warmest phase of the last ~5500 years. During 700-500 aBP, the climate and environment tended to be cool and arid again. These climate-environment changes happening during the middle and late Holocene in alpine belt of Taibai Mountain are generally similar to the changes at some sites in the region influenced by the East Asian monsoon in China since these sites are all under the influence of East Asian monsoon.

Key words: Foye Chi, lake sediments, Taibai Mountain, alpine belt, palaeoenvironment changes

摘要：

佛爷池为秦岭主峰太白山南坡高山带的冰蚀湖。在其干涸的底床挖掘一条深70 cm 的探坑, 自坑壁取得沉积物样品。对这一剖面的3个样品做加速器质谱(AMS)¹⁴C 测年, 56个样品做总有机碳含量(TOC)和碳/氮比值(C/N)分析、低频磁化率(χ_lf)和非滞后性剩磁(ARM)测试、粒度分析和孢粉分析, 并计算ARM/χ_lf。利用这些测年结果建立这一剖面的年代框架, 并对TOC 和C/N, χ_lf, ARM 和ARM/χ_lf, 平均粒径及栎属孢粉(Qucercus)含量在剖面中的变化进行解译, 由此初步推测佛爷池周边距今5520 年以来的气候及环境变化。在5520~3800 aBP, 气候为冷干, 在其中的5100~4300 aBP 冷干程度可能最强。在3800~2300 aBP, 气候渐转暖湿。在300~1300 aBP, 气候更为湿润。在1300~700 aBP, 气候更为温暖,可能是过去5500 多年中最温暖的时期。在700~500 aBP, 气候再度变冷、变干。由于共同受到东亚季风的影响, 太白山高山带中、晚全新世这一气候?环境变化与中国东亚季风区一些地点的变化趋势颇为相似。

关键词: 佛爷池, 湖泊沉积物, 太白山, 高山带, 古气候-环境变化