A multimethod dating study of ancient permafrost, Batagay megaslump, east Siberia
A multimethod dating study of ancient permafrost, Batagay megaslump, east Siberia
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DOI：
10.1017/qua.2021.27
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发表时间：
2021-06
影响因子：
2.3
通讯作者：
J. Murton;T. Opel;P. Toms;A. Blinov;M. Fuchs;Jamie C. Wood;A. Gärtner;S. Merchel;G. Rugel;G. Savvinov;S. Wetterich
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作者：
J. Murton;T. Opel;P. Toms;A. Blinov;M. Fuchs;Jamie C. Wood;A. Gärtner;S. Merchel;G. Rugel;G. Savvinov;S. Wetterich
摘要 古代永久冻土的年代测定对于了解长期永久冻土稳定性和解释古环境条件至关重要，但对地质年代学提出了巨大的挑战。在这里，我们对东西伯利亚巴塔盖巨型滑坡的永久冻土应用了四种方法：（1）石英的光刺激发光（OSL）测年，（2）钾长石的后红外红外刺激发光（pIRIR）测年，（3）有机材料的放射性碳测年，以及（4）冰楔的 36Cl/Cl 测年。所有四个天文钟都产生地层一致且可比较的年龄。然而，OSL 似乎比 pIRIR 更可靠地确定海洋同位素阶段 (MIS) 3 到 MIS 2 沉积物的年代，而后者与较旧沉积物的 36Cl/Cl 年龄更一致。下层冰复合体至少形成于 650ka，可能在 MIS 16 期间形成，代表了白令海峡西部最古老的永久冻土和北半球已知第二古老的冰。它经历了多次间冰期，包括超间冰期 MIS 11c，但解冻不整合面和侵蚀面表明至少有一次永久冻土融化和侵蚀发生在 MIS 16 至 6 之间的某个时间。上部冰复合体形成于 MIS 4 至 3 晚期的至少 60 至 30 ka 期间。上部冰复合体上方的砂单元可追溯至 MIS 3-2，而下方的砂单元可追溯至 MIS 3-2。成立于 MIS 4 和 16 之间的某个时间。
Abstract Dating of ancient permafrost is essential for understanding long-term permafrost stability and interpreting palaeoenvironmental conditions but presents substantial challenges to geochronology. Here, we apply four methods to permafrost from the megaslump at Batagay, east Siberia: (1) optically stimulated luminescence (OSL) dating of quartz, (2) post-infrared infrared-stimulated luminescence (pIRIR) dating of K-feldspar, (3) radiocarbon dating of organic material, and (4) 36Cl/Cl dating of ice wedges. All four chronometers produce stratigraphically consistent and comparable ages. However, OSL appears to date Marine Isotope Stage (MIS) 3 to MIS 2 deposits more reliably than pIRIR, whereas the latter is more consistent with 36Cl/Cl ages for older deposits. The lower ice complex developed at least 650 ka, potentially during MIS 16, and represents the oldest dated permafrost in western Beringia and the second-oldest known ice in the Northern Hemisphere. It has survived multiple interglaciations, including the super-interglaciation MIS 11c, though a thaw unconformity and erosional surface indicate at least one episode of permafrost thaw and erosion occurred sometime between MIS 16 and 6. The upper ice complex formed from at least 60 to 30 ka during late MIS 4 to 3. The sand unit above the upper ice complex is dated to MIS 3–2, whereas the sand unit below formed at some time between MIS 4 and 16.