泥河湾黑土沟剖面磁组构特征及古湖水文环境变化  

Paleohydro-climatic changes revealed by anisotropy of magnetic susceptibility at the Heitugou section,Nihewan Basin,and its influences on human’s occupation

作　　者：唐锐枰 葛俊逸[1,2,3] 庞海娇 欧阳志山 Ruiping Tang;Junyi Ge;Haijiao Pang;John W.Olsen(Key Laboratory of Vertebrate Evolution and Human Origins,Institute of Vertebrate Paleontology and Paleoanthropology,Chinese Academy of Sciences,Beijing 100044,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Center for Excellence in Life and Paleoenvironment,Chinese Academy of Sciences,Beijing 100044,China;Luanchuan Cultural Relics Conservation Institute,Luanchuan 471500,China;School of Anthropology,University of Arizona,Tucson,AZ 85721,USA)

机构地区：[1]中国科学院古脊椎动物与古人类研究所中国科学院脊椎动物演化与人类起源重点实验室,北京100044 [2]中国科学院大学地球与行星科学学院,北京100049 [3]中国科学院生物演化与环境卓越创新中心,北京100044 [4]栾川县文物管理所,栾川471500 [5]School of Anthropology,University of Arizona,Tucson,AZ 85721,USA

出　　处：《科学通报》2020年第11期1027-1045,共19页Chinese Science Bulletin

基　　金：国家自然科学基金(41672352,41888101,41690110,41430531);中国科学院B类战略性先导科技专项(XDB26000000)资助。

摘　　要：古人类栖息地古气候-水文环境变化与古人类的生存活动密切相关.泥河湾盆地保存着大量早更新世以来的古人类遗址,完整地记录了我国北方古人类的活动历史.但迄今对其水文环境变化历史以及与古人类生存活动联系的研究仍显不足.本研究对位于盆地东部的黑土沟遗址剖面进行了系统的磁化率地层学和磁组构研究.通过与邻近大长梁和小长梁剖面的精细磁化率地层对比,发现黑土沟剖面堆积约始于1.9 Ma,可能记录了我国北方中高纬地区最早的古人类活动.详细的磁组构研究结果显示,磁化率各向异性能够有效地揭示泥河湾盆地1.9 Ma以来的古水文变化,黑土沟剖面的磁组构变化显示泥河湾古湖水文环境发生了多次阶段性变化.1.9 Ma前后,壶流河的出现,抑或研究区发生构造沉降,使得研究区堆积厚层砂砾石,较强的水动力和水位升高使得古人类向高处迁移;1.9~1.8 Ma期间,古湖扩张,湖面上升,水动力减弱,可能指示了东亚夏季风的增强.1.8~1.5 Ma,古湖水动力显著增强,而后持续减弱.1.5~1.3 Ma,水动力显著降低,可能与东亚季风降水增加,气候逐渐变得暖湿,湖水显著加深,而使得河流输入影响减弱有关.1.3~0.9 Ma,水动力较强但呈现频繁的大幅波动,湖泊水文环境变化剧烈,可能是中更新世气候转型事件的响应.0.9~0.4 Ma,湖泊再度加深,古湖沉积水动力变化显著受控于全球冰量呈现周期性的大幅波动.上述水文变化显著影响着古人类的生活行为,很大程度上决定了泥河湾古人类遗址的时空分布特征.Paleohydro-climatic changes in the habitats of early humans are closely related to their evolution and occupation of specific niches.In the Nihewan Basin of North China,a large number of archaeological sites dating back to the early Pleistocene have been discovered which record the occupation history of human ancestors in the region.However,thus far,studies of the history of paleohydro-climatic changes in the Nihewan Basin and their influences on human occupation remain insufficient.Here,we report the results of a systematic investigation of variations in the anisotropy of magnetic susceptibility(AMS)and magnetic susceptibility stratigraphy in the Heitugou(HTG)section to partially rectify this paucity of data and interpretations.The HTG section is located in the eastern Nihewan Basin where,in 2006,a Paleolithic site was discovered and excavated at the bottom of the sequence.By comparing detailed magnetic susceptibility sequences in the HTG section with those of the nearby Xiaochangliang and Dachangliang sections,we found that the sedimentation of the HTG section began about 1.9 Ma,indicating that the HTG archaeological site possibly records the earliest human occupation of middle-to-high latitude North China.Our studies of the AMS in the HTG section indicate that it is characterized by a primary sedimentary magnetic fabric without significant disturbance,demonstrating its potential for tracing regional paleo-hydrological changes.In most samples dating between 1.9 Ma and 0.4 Ma,the maximum susceptibility axes(Kmax)cluster along the SE-NW vector,suggesting hydrodynamic changes tracable in the study area were mainly influenced by the Huliu River.In addition,a relatively weak Kmaxdirection biased towards the SW-NE axis was also observed,possibly generated by the predominant flow of the Sanggan River.These two rivers–the Huliu and Sanggan–determined the paleohydrological changes in the eastern Nihewan paleolake basin.Meanwhile,AMS studies also suggest multiple-phase hydrodynamic changes in the Nihewan Basin.Around

关 键 词：泥河湾古湖 古水文 古人类 黑土沟 磁化率各向异性 

分 类 号：K878[历史地理—考古学及博物馆学] P534.6[历史地理—历史学] P343.3[天文地球—古生物学与地层学]