Timing and implications of aeolian sand accumulation in a alpine basin of Qilian Shan, NE Tibetan Plateau
Timing and implications of aeolian sand accumulation in a alpine basin of Qilian Shan, NE Tibetan Plateau
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DOI：
10.3389/feart.2022.939887
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发表时间：
2022-08
期刊：
影响因子：
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通讯作者：
N. Yang;Jingran Zhang;Yun-He Cai;Yuye Feng;Linhai Yang;Hongyi Cheng;H. Long
中科院分区：
文献类型：
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作者：
N. Yang;Jingran Zhang;Yun-He Cai;Yuye Feng;Linhai Yang;Hongyi Cheng;H. Long
青藏高原东北部地区全新世以来的区域水分和气候变化的重建工作已在不同地质档案的基础上展开。然而，由于缺乏可靠的独立年代学或气候代用指标的模糊解释以及高原内部复杂的地理环境，全新世环境变化的性质及其影响因素仍然存在争议，特别是在最佳气候条件（有效水分峰）是否占上风，在早或中期全新世。本文报道了祁连山东南部八宝河流域沙窝头砂场的一个新的沙丘堆积记录，以揭示晚冰期和全新世的水分变化历史。利用粗粒钾长石后红外释光测年技术，对两个剖面的49个样品进行了风成砂和古土壤的年代学研究。通过对沙丘/古土壤剖面的地层学研究表明，晚冰期-全新世早期（14-8 ka）气候条件非常干燥，以沙丘形成为特征，全新世中期（8- 4ka）水分达到高峰，成壤作用最强，全新世晚期（4ka以来）气候条件相对干燥。青藏高原东北部地区全新世水分变化的区域对比表明，青藏高原东北部地区全新世水分变化具有同步性，即早全新世和晚全新世干旱，而全新世中期水分达到峰值，这可能与东亚夏季风的降水变化有关。
The reconstruction of regional moisture and climate changes during the Holocene has been intensively carried out over the NE Tibetan Plateau, based on different geological archives. However, owing to either the lack of robust independent chronology or ambiguous interpreting of climate proxies as well as complex geographic settings within the plateau, the nature of Holocene environmental changes and their influence factors remain controversial, particularly on whether the optimal climate condition (effective moisture peak) has prevailed during the early- or mid-Holocene. In this study, we reported a new well-dated sand dune accumulation record from the Shawotou sand field in the Babao River drainage area in the southeast Qilian Mountains, to unravel the late glacial and Holocene moisture variation history. The robust chronologies of aeolian sands and palaeosols from two sections were established based on densely collected 49 samples using post-infrared (IR) IR-stimulated luminescence dating of coarse-grained K-feldspar. Based on stratigraphic investigation of the sand dune/palaeosol sections, the results show that the climatic condition was very dry during the late glacial and early Holocene (14–8 ka), characterized by sand dune formation, and then the moisture peaked in the middle Holocene (8–4 ka) with the strongest pedogenesis, followed by a relatively dry condition in the late Holocene (since 4 ka). The regional comparison suggested that the Holocene moisture variation pattern seems synchronous over the NE Tibetan Plateau, that is, the dry early Holocene and late Holocene but with peaked moisture in the middle Holocene, which is likely attributed to the precipitation changes of the East Asian summer monsoon.