周助,
迟长婷,
陆璐,
王均平,
魏明建,
首都师范大学资源环境与旅游学院, 北京 100048
基金项目: 国家自然科学基金项目(批准号：41771224)资助
详细信息
作者简介: 田晏嫣, 女, 31岁, 博士, 全球环境变化研究, E-mail:tianyaner0718@126.com
通讯作者: 魏明建, E-mail:weimj@cnu.edu.cn
中图分类号: P532;P534.63+1收稿日期:2020-06-20
修回日期:2020-09-06
刊出日期:2020-11-30
The paleoclimate change period of the Late Pliocene-Early Pleistocene recorded by pollen from core PL02 in Yinchuan Basin
Tian Yanyan,Zhou Zhu,
Chi Changting,
Lu Lu,
Wang Junping,
Wei Mingjian,
College of Resource Environment and Tourism, Capital Normal University, Beijing 100048
More Information
Corresponding author: Wei Mingjian,E-mail:weimj@cnu.edu.cn
MSC: P532;P534.63+1--> Received Date: 20 June 2020
Revised Date: 06 September 2020
Publish Date: 30 November 2020
摘要
摘要:晚上新世-早更新世时期是全球环境发生转折的重要过渡时期。银川盆地位于中国西北内陆地区，同时又处于干旱与半干旱区域的交界地带，在盆地内部蕴藏着丰富的新生代沉积，是研究古环境演化的理想区域，深度为720.77 m的PL02钻孔位于盆地内部的沉降中心附近，属于典型沉降盆地的洪泛沉积环境。本文选取银川盆地PL02钻孔下部(深度705.7~247.9 m)晚上新世-早更新世时期(古地磁年龄3.3~1.5 Ma)的孢粉、磁化率及粒度等指标，通过孢粉分析、频谱分析和小波变换等方法，恢复了银川盆地晚上新世-早更新世时期的古环境演化特征，并对该时期的古气候变化周期进行分析。研究结果显示：银川盆地在晚上新世时期(约2.8 Ma)气候已经开始逐渐变冷变干；进入早更新世时期(约2.6 Ma)，研究区气候变得更加干旱并且冷暖波动较大；同时，孢粉、磁化率和粒度等指标均反映出银川盆地晚上新世-早更新世时期古气候变化具有较显著的约20 ka的岁差周期与约40 ka的地轴倾角周期，但约100 ka的地球轨道偏心率周期仅在个别指标中有所表现。另外，本研究结果与中国黄土高原和深海氧同位素记录所揭示的晚上新世-早更新世时期气候变化周期较为一致。因此，认为银川盆地在该时期的气候波动可能受到了地球轨道因素的影响，且与全球环境变化具有相似性。
关键词: 银川盆地/
晚上新世-早更新世/
古气候/
天文周期
Abstract:The Late Pliocene-Early Pleistocene period is a transitional period of major changes in the global environment. The Yinchuan Basin(37°50'~39°20'N, 105°21'~106°50'E) is located in Northwestern China and in the junction of arid and semi-arid regions. The basin is an ideal area for studying the evolution of the paleoenvironment since it's abundant Cenozoic sediments. A depth 720.77-m core PL02(38°55'26.62″N, 106°36'03.82″; 1103 m a.s.l.) is located in the subsidence central of Yinchuan Basin and it is typical flood sedimentary environment of subsidence basin. In this study, we reconstructed paleoenvironment evolution characteristics during the Late Pliocene-Early Pleistocene(3.3~1.5 Ma) period in Yinchuan Basin by pollen(200 samples), magnetic susceptibility and mean grains size of the bottom of the core PL02(depth:705.7~247.9 m). Moreover, we also analyzed the paleoclimate change cycle of this period through spectrum analysis and wavelet transform methods. The results show that the climate in the study area has gradually become cold and dry during the Late Pliocene period(since 2.8 Ma), and has become more arid and fluctuates greatly in the Early Pleistocene period. In addition, pollen, magnetic susceptibility and mean grains size reflected that the paleoclimate changes in Yinchuan Basin from the Late Pliocene to Early Pleistocene period have a relatively significant cycles of ca. 20 ka of the precession and of ca. 40 ka of the obliquity, but the cycles of ca. 100 ka of the eccentricity is only reflected in individual indicators. Moreover, these results are more consistent with the climate change cycle of the Late Pleistocene-Early Pleistocene revealed by the records of the Loess Plateau and the deep-sea oxygen isotope records. Therefore, it can be speculated that the climate fluctuations in the Yinchuan Basin during this period may be affected by the Earth's orbital factors and similar to global environmental change.
Key words:Yinchuan Basin/
Late Pliocene-Early Pleistocene/
paleoclimate/
astronomical period
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