摘要
研究中国北方沙漠/沙地在地质历史上典型暖期的古环境对预测和认识未来该地区环境演化趋势至关重要。然而,由于风沙沉积序列在时间上的不连续性及空间分布上的不均一性,造成对沙漠/沙地在地质历史时期环境特征的解读存在或然性。本研究应用国际耦合模式比较计划第六阶段(CMIP6)-第四轮古气候模拟国际比较计划(PMIP4)提供的古气候模拟数据,重建深海氧同位素5e阶段(MIS 5e)和中全新世时期(MH)中国北方沙漠/沙地的沙丘活化指数、潜在地表湿度和风速等参数,并结合对应时期的地质记录,探讨风沙活动特征及其驱动机制。研究结果表明:1)与工业革命前相比,MIS 5e和MH时期的中国北方东部沙地和中部沙漠的风沙活动减弱,而西部沙漠地区的风沙活动则有所增强,尤其在MIS 5e阶段表现更为突出;2)MIS 5e和MH时期东亚夏季风的增强,导致东部沙地和中部沙漠地区降水增加,改善了潜在地表湿度,抑制地表风沙活动;3)MIS 5e和MH时期西风带呈现北退趋势,致使在西部沙漠降水减少,但由于温度升高导致周边山地的冰雪融水增加,使得沙区河湖相沉积发育,降水减少导致的沙漠腹地地表湿度条件恶化以及河湖相沉积带来的大量潜在沙源使得西部沙漠部分地区风沙活动增强;4)在MIS 5e和MH时期,中国北方沙漠/沙地的近地表风速显著下降,不仅降低了地表沉积物的搬运能力,同时也降低了植被被掩埋的概率,为抑制风沙活动的发生提供了重要的前提条件。
The desert belt of northern China includes mainly four sandy lands(Maowusu,Hunshandake,Horqin,Hulunbeier)and eight sand seas(Taklamakan,Gurbantunggut,Kumtag,Chaidamu,Badain Jaran,Tengger,Wulanbuhe,Kubuqi),extending from 35°N to 50°N and from 75°E to 125°E.Therefore,studying the paleoenvironmental characteristics of the vast desert areas in northern China during warm periods(e.g.,MIS 5e and mid-Holocene)is essential for predicting and understanding the future scenarios of environments under global warming.However,due to the temporal discontinuity and spatial distribution gap of aeolian sand deposition,there are uncertainties in interpreting the paleoenvironmental characteristics of the desert belt in northern China during the MIS 5e and the mid-Holocene.Here we used the paleoclimate models provided by the Coupled Model Intercomparison Project Phase 6(CMIP6)-the Paleoclimate Modeling Intercomparison Project Phase 4(PMIP4)to analyze the dune mobility index,aridity index and near-surface wind during the MIS 5e and the mid-Holocene.Additionally,we combined probably robust age data from 125 published geological records(including lacustrine and alluvial sediments,aeolian-paleosol sequences)with paleoclimate simulations to reveal the characteristics and driving mechanisms of aeolian activity in the desert belt of northern China during the two warm periods studied herein.Our results show that:(1)As indicated by the decreased dune mobility index,aeolian activity weakened in the eastern and central portions of the desert belt in northern China during the MIS 5e and the mid-Holocene in contrast to the preindustrial period.However,a notable intensification of aeolian activity occurred in the western portion,especially during the MIS 5e.(2)The enhanced East Asian summer monsoon during warm periods resulted in increased precipitation in the eastern and central portion of the desert belt,improving surface moisture conditions,and thus suppressing aeolian activity.(3)Simultaneously,in the western portion,the westerly jet retre
作者
郑珺戈
张德国
杨小平
ZHENG Junge;ZHANG Deguo;YANG Xiaoping(School of Earth Sciences,Zhejiang University,Hangzhou 310058,Zhejiang)
出处
《第四纪研究》
CAS
CSCD
北大核心
2024年第6期1612-1632,共21页
Quaternary Sciences
基金
国家自然科学基金重点项目(批准号:42230502)资助。
