中天山山间盆地中晚全新世植被与气候变化
- 收稿日期:
2023-12-28
- 网络出版日期:
2024-07-02
摘要: 【目的】新疆天山居亚欧大陆内部，处多个大气环流系统过渡地带，对气候变化响应敏感，学术界对其全新世环境演化的认识尚未统一，补充更多敏感区域高分辨率气候记录是明确该问题的基础。【方法】研究材料采自中天山山间盆地，基于AMS14C年代测试结果，以孢粉为古气候代用指标，重建了研究区中晚全新世以来的植被与气候变化过程。【结果】6369-3601 cal yr B.P.期间蒿属(Artemisia)、藜属(Chenopodium)含量高，花粉PCA axis 1得分偏正，气候出现干湿波动，以干为主，存在气候突变现象。3601-2512 cal yr B.P.期间云杉属(picea)含量升高，花粉PCA axis 2得分偏正，气候冷湿。2512-1016 cal yr B.P.期间桦木属(Betula)含量增加，花粉PCA axis 1得分偏正，气候暖干。发生在4766-3601 cal yr B.P.期间以冷干为特征的气候突变与“4.2 ka B.P.”气候事件有良好响应，可能是太阳辐射减弱，中高纬寒冷加剧、北大西洋海温降低使西风环流减弱导致。【结论】划分出的3个花粉带指示中天山山间盆地中晚全新世气候经历了干湿波动(偏干)-冷湿-暖干3个阶段。中晚全新世以来研究区接收夏季太阳辐射减少，北大西洋海面蒸发弱，西风环流携带水汽少，气候干旱。晚全新世早期持续的寒冷气候迫使西风环流南移，叠加北大西洋涛动负相位输送大量水汽，气候冷湿。晚期冬季太阳辐射增强，陆地蒸发加大，气候暖干。
Middle and Late Holocene vegetation and climate change in the intermountain basin of Middle Tianshan Mountains, Xinjiang, China
- Received Date:
2023-12-28
- Available Online:
2024-07-02
Abstract: [Objective] The Tianshan Mountains in Xinjiang are located in the inner part of the Asia-Europe continent, in the transition zone between the westerly and monsoon circulations, and are sensitive to climate change. Academics have not yet united on the understanding of the Holocene environmental evolution in the region, and supplementing more high-resolution climatic records in the sensitive areas is the basis for clarifying this issue. [Methods]The study material was taken from the Middle Tien Shan Intermountain Basin, we reconstructed the vegetation and climate change processes in the study area since the Middle and Late Holocene, based on the AMS14C dating results and using sporadic pollen as a paleoclimate proxy. [Results and Discussions] 6369-3601 cal yr B.P. The period of Artemisia and Chenopodium was characterized by high content, positive pollen PCA axis 1 scores, and wet-dry fluctuations in the climate, with dryness as the dominant factor and abrupt climate change. 3601-2512 cal yr B.P. The period of spruce Picea content was characterized by elevated content, positive pollen PCA axis 2 scores, and cold-wet climate. 2512-1016 cal yr B.P. The period of Betula was characterized by increased content, positive pollen PCA axis 1 transitionscores, warm dry climate. [Conclusion] The three pollen zones indicate that the Middle and Late Holocene climate in the Zhongtianshan Intermontane Basin went through 3 phases of wet-dry fluctuations (off-dry)-cold-wet-warm-dry. Since the middle to late Holocene, the study area has received less solar radiation in summer, Weak evaporation from the North Atlantic sea surface and low water vapor carried by the westerly circulation, the climate has been arid. in the early Late Holocene, the westerly circulation shifted to the south, Superimposed negative phase of the North Atlantic Oscillation (NAO) transporting large amounts of water vapor and the climate was cold and humid. Then the climate became warm and dry due to the increase of solar radiation in the late winter. The abrupt climate change characterized by cold and dry conditions during 4766-3601 cal yr B.P. was a response to the "4.2 ka B.P." climatic event, which may have been caused by the weakening of the westerly circulation due to the weakening of solar radiation, the intensification of the cold in the middle and high latitudes, and the lowering of the SST in the North Atlantic Ocean.
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