A framework for Late Quaternary lake-level fluctuations in Lake Karakul, eastern Pamir, focusing on lake–glacier landform interaction
A framework for Late Quaternary lake-level fluctuations in Lake Karakul, eastern Pamir, focusing on lake–glacier landform interaction
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DOI：
10.1016/j.geomorph.2010.03.025
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发表时间：
2010-07
期刊：
影响因子：
3.9
通讯作者：
T. Komatsu;Teiji Watanabe;K. Hirakawa
中科院分区：
文献类型：
--
作者：
T. Komatsu;Teiji Watanabe;K. Hirakawa
本文在遥感立体观测、野外填图和相对测年的基础上，建立了帕米尔高原东部“卡拉库尔湖”闭盆湖晚第四纪湖位波动的框架。卡拉库尔湖周围观测到的古岸线（约60条）按高度由高到低可分为H、M、L、LL四组。上述古岸线群的最高高度分别高于现湖平面（海拔3915m） 205m、85m、35m和10m。从目前盆地闭合阈值附近的冰川地貌发育和相关的谷填沉积模式来看，这些古岸线群定义的湖平面波动是封闭盆地内水平衡变化的结果。在古湖泊高地形成的时间上，湖泊阶地与终碛垄的关系表明，各古湖泊的最高高地与相应的最大冰川推进具有同步性。综合地貌发育类型和相关的冰川作用、冰碛砾石的相对定年以及与帕米尔及其周围已确定的冰川历史的相关性，建立了湖平面波动的初步年代学。H线、M线、L线和LL线代表的古湖泊高地的时期与末次冰期前（MIS 8）、末次冰期前（MIS 6）、末次冰期早期（MIS 4）和末次冰期晚期（MIS 2）有关。根据这一年代学，60条古岸线中的每一条都显示了从MIS 8、6、4和2冰川最大值结束的湖泊退退阶段的稳定湖面。考虑到各古岸线群的独特地貌形成与古湖泊的主要停滞或小的再海侵有关，短期的降温和（或）湿润期使湖泊水文平衡由负向正转变，叠加在冰川终止期的主要古气候变化上。
This paper presents a framework for Late Quaternary lake-level fluctuation in the closed-basin lake “Lake Karakul” (eastern Pamir) on the basis of the stereoscopic observation of remote sensing data, field mapping and relative dating. The palaeoshorelines (approximately 60 in number) observed around the Lake Karakul can be classified into four groups: H Shorelines, M Shorelines, L Shorelines and LL Shorelines (in the descending order of height). The highest level of each of the above palaeoshoreline groups is 205m, 85m, 35m and 10m above the present lake level (3915m asl). From the glacial landform developments and related valley-fill sedimentation patterns around the threshold of the present basin closure, the lake-level fluctuation defined by these palaeoshoreline groups was found to be a consequence of the water balance change within the closed basin. With respect to the timing of the palaeolake highstands, the relationship between lacustrine terraces and terminal moraines suggests the synchroneity of the highest stand of each palaeolake with the corresponding maximum glacier advance. The tentative chronology of the lake-level fluctuation was established from the synthesis of the style of geomorphic development and related glaciation, relative dating on moraine gravels, and the correlations to established glacial histories in and around the Pamir. The periods of the palaeolake highstands indicated by H, M, L and LL shorelines seem to be correlated with the antepenultimate glacial (MIS 8), penultimate glacial (MIS 6), early last glacial (MIS 4) and the late last glacial (MIS 2) periods, respectively. Based on this chronology, each of the 60 palaeoshorelines are expected to show stable lake surfaces during lake regressive stages toward the terminations from the glacial maxima of MIS 8, 6, 4 and 2. Given that the distinct landforms of each palaeoshoreline group were formed in association with the predominant stagnation or small re-transgression of the palaeolake, the short-term cooling and/or wetter episodes, which turned positive lake hydrologic balances from negative ones, were superimposed on the major palaeoclimate changes during the glacial termination periods.