Revisiting growth and decline of late Quaternary mega-lakes across the south-central Tibetan Plateau
Revisiting growth and decline of late Quaternary mega-lakes across the south-central Tibetan Plateau
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DOI：
10.1016/j.quascirev.2020.106475
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发表时间：
2020-11
影响因子：
4
通讯作者：
T. Jonell;J. Aitchison;Guoqiang Li;J. Shulmeister;R. Zhou;Haixia Zhang
中科院分区：
文献类型：
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作者：
T. Jonell;J. Aitchison;Guoqiang Li;J. Shulmeister;R. Zhou;Haixia Zhang
湖泊盆地记录了水圈、冰冻圈和大气之间的重要相互作用。它们的沉积物和海岸线地貌记录了不同时间尺度上过去气候变化和环境影响的时间、持续时间和强度。今天，成千上万的湖泊系统遍布青藏高原的内部排水系统，其中许多只是过去更广阔的古湖泊的含盐遗迹。这项研究提出了新的海岸线年龄与定量数字地形分析和区域地貌证据相结合，以重建青藏高原中南部晚第四纪裂谷湖泊系统的规模和范围。本研究提出了光释光（OSL）和第一个钾长石后红外（pIRIR）激发发光年龄Zabuye Caka和达瓦措和测试，如果这些湖泊曾经是一个单一的更新世大型湖泊的一部分，建立在四个南北裂谷系统。新的研究结果表明，龙格尔地区在更新世末-全新世初发育了两个规模较大但相互独立的古湖泊系统，至少41 ka以来没有出现过面积大于6460 km ~ 2的湖泊。全新世早期古湖泊扩展到现代的7倍（+220-335 km 3），与东部相比，西部有两到四倍的不对称湖泊扩展。研究结果证实了早期的调查，这意味着显着的径流量增加和/或蒸散量减少，促使快速最早的全新世湖泊扩张。降水量的变化，结合冻土退化，温度和风强度，古湖泊水分平衡。开放系统的湖泊行为和不断变化的排水配置在复杂的地形解释延迟的湖泊退化和间歇性湖泊衰退的开始。这表明，突然的全新世气候变化并不一定需要间断的湖泊衰退。最后，西藏和东非裂谷湖泊之间独特的地貌和古气候相似性突出了一些西藏古湖泊在短期和地质时间尺度上作为自然气候放大器的潜力。
Lake basins record critical interactions between the hydrosphere, cryosphere and atmosphere. Their sediments and shoreline landforms archive timing, duration, and intensity of past climatic variability and environmental impacts over a variety of timescales. Thousands of lake systems spread across the internally drained Tibetan Plateau today, of which many are only the salty remains of much more expansive paleolakes in the past. This study presents new shoreline ages integrated with quantitative digital topographic analysis and regional geomorphic evidence to reconstruct the sizes and extents of late Quaternary rift lake systems for the south-central Tibetan Plateau. This study presents optically stimulated luminescence (OSL) and the first K-feldspar post-infrared infrared (pIRIR) stimulated luminescence ages for Zabuye Caka and Dawa Tso and tests if these lakes were once part of a singular Pleistocene mega-lake established across four N–S rift systems. Our new results show that two large but separate paleolake systems developed in the latest Pleistocene-earliest Holocene and no lake larger than ∼6460 km2has existed since at least 41 ka in the Lunggar region. Early Holocene paleolakes expanded up to 7× modern (+220–335 km3) with two to four-fold asymmetric lake expansion in the west compared to the east. Findings corroborate earlier investigations, implying that dramatic runoff increase and/or evapotranspiration reduction prompted rapid earliest Holocene lake expansion. Precipitation variability, in combination with permafrost degradation, temperature and wind strength, governed paleolake moisture balance. Open-system lake behavior and evolving drainage configurations across complex topography explain delayed onsets of lake regression and punctuated lake decline. This suggests abrupt Holocene climate shifts are not necessarily required for punctuated lake decline. Lastly, unique geomorphological and paleoclimatic similarities between Tibetan and East African rift lakes highlight the potential for some Tibetan paleolakes to function as natural climate amplifiers over both short and geologic timescales.