摘要
黄土是公认的三大古气候记录载体之一,全新世黄土由于位于顶层极易受到人类活动的影响,故研究程度不高。最近在甘肃会宁白草塬发现一个沉积连续、分辨率高、且保存完整的全新世黄土剖面,该剖面忠实地记录了全新世古气候演化,能够很好地与三宝洞和葫芦洞石笋氧同位素记录全新世古气候进行对比:二者共同记录了约12.5～11.5ka之间的Younger Dryas冷干事件;约10.5～5.2ka全新世适宜期,但是适宜期中气候变化具有不稳定性;5.2ka至今,气候较全新世适宜期慢慢变干变冷,二者相互印证了东亚季风区全新世古气候演化的一般过程;而驱动二者演化主要因素是太阳辐射量的变化。位于黄土高原西北边缘的会宁白草塬剖面中的磁化率和粒度两参数相比较:粒度较磁化率波动更频繁,记录古气候变化更灵敏。
Climate change is closely related to people＇s livelihood,Holocene is the nearest geologic epoch we are living. Holocene climate change is therefore particularly important to human beings. It is known that aeolian loess deposit in China is one of the best geological recorders for paleoclimatie change. As position of Holocene loess is on the top layer of loess sequence, it may be easily disturbed by human activities. That is why the achievement of studying paleoclimatic change based on Holocene loess is not high so far. Here we report a continuous and integrity Holocene loess section in Baicaoyuan （ 36~ 14. 390＇N, 105 ~08. 032＇E） , Huining County, Gansu Province. This high resolution section is located in the northwest edge of Loess Plateau. The total thickness of the section we sampled is 2.2m, 110 samples were sampled with 2cm interval. Among them, the thickness of Lo is lm, with pale yellow color, loose, massive ,many grass roots and wormholes. The thickness of So is 0. 96m,with black brown color, hard texture ,white calcium toadstools,many grass roots and wormholes; the thickness of L1 is 0.24re,with many pores showing looser than Lo , its color is also light than that of Lo. The section recording the evolution of Holocene climate change can be beautifully correlated with oxygen isotope of stalagmite in Sanbao and Hulu. This record showing the cold and dry Younger Dryas event is during about 12.5 - ll.5ka period; the Holocene Climate Optimum （with higher temperature and precipitation）is during about 10.5-5.2ka period. However, climate is not stabilizing during the Holocene Climate Optimum; it becomes dry and cold gradually since 5.2ka. Baicaoyuan,Sanbao and Hulu Cave are all in the East Asian monsoon area. They have the similar evolution, so their similar tendency of curves indicates a general evolution process of Holocene paleoclimate. The evolution of Holocene climate change follows closely to the solar radiation, we thus attribute its driving factor to variation of orbital parameter, the most
出处
《第四纪研究》
CAS
CSCD
北大核心
2012年第4期777-784,共8页
Quaternary Sciences
基金
国家自然科学基金项目(批准号:41072124
40830105和40721061)资助
关键词
全新世
黄土
气候演化
灵敏性
Holocene, loess, climate evolution, sensitivity
