Reconstruction of Holocene environmental changes in Southern Kurils (North-Western Pacific) based on palaeolake sediment proxies from Shikotan Island
Reconstruction of Holocene environmental changes in Southern Kurils (North-Western Pacific) based on palaeolake sediment proxies from Shikotan Island
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DOI：
10.1016/j.gloplacha.2017.10.005
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发表时间：
2017-12
影响因子：
3.9
通讯作者：
L. Nazarova;Т. А. Grebennikova;N. Razjigaeva;L. Ganzey;N. Belyanina;K. Arslanov;V. Kaistrenko;А. О. Gorbunov;А. А. Kharlamov-А.;N. Rudaya;O. Palagushkina;B. Biskaborn;B. Diekmann
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作者：
L. Nazarova;Т. А. Grebennikova;N. Razjigaeva;L. Ganzey;N. Belyanina;K. Arslanov;V. Kaistrenko;А. О. Gorbunov;А. А. Kharlamov-А.;N. Rudaya;O. Palagushkina;B. Biskaborn;B. Diekmann
通过对位于小千岛群岛色当岛海岸带的一个古湖泊剖面的有机沉积物地球化学和生物组分（硅藻、摇蚊、花粉）的研究，重建了全新世的古环境变化和古事件（海啸、海平面波动和滑坡）。在8000年的沉积过程中，有机沉积物地球化学、硅藻和摇蚊的组成以及陆地植被组成的变化表明，在距今5800 calyr BP之前的时期，气候以温暖湿润（相当于中全新世最佳时期）为特征，此后气候变冷。一个温暖的时期重建从约900至至少约580 cal yr BP对应的过渡到奈良-平安-镰仓温暖的阶段，可以与中世纪温暖期。580 cal yr PB后，湖泊逐渐干涸，气候信号不能从下降的湖泊生物群落中获得，但云杉的作用增加和橡树从植被中的消失提供了气候变冷的证据，可以与LIA。研究区海退阶段为ca 6200 -5900（中全新世海侵末期）、ca 5500 -5100（中绳文海退或Kemigawa海退）和ca 1070 -360 cal yr BP（平安海侵末期）。沉积物的岩性结构和硅藻的组成提供了证据，在岛上的多个不同强度的海啸事件。其中最显著的年代为距今约7000、6460、5750、4800、950 cal/yr BP。新的研究结果有助于了解作为西北太平洋地区千岛-堪察加和阿留申边缘海-岛弧系统一部分的南千岛群岛的全新世环境历史。
We investigated a well-dated sediment section of a palaeolake situated in the coastal zone of Shikotan Island (Lesser Kurils) for organic sediment-geochemistry and biotic components (diatoms, chironomids, pollen) in order to provide a reconstruction of the palaeoenvironmental changes and palaeo-events (tsunamis, sea-level fluctuations and landslides) in Holocene. During theca8000 years of sedimentation the changes in organic sediment-geochemistry and in composition of the diatoms and chironomids as well as the shifts in composition of terrestrial vegetation suggest that the period untilca5800 cal yr BP was characterized by a warm and humid climate (corresponds to middle Holocene optimum) with climate cooling thereafter. A warm period reconstructed fromca900 to at leastca580 cal yr BP corresponds to a transition to a Nara-Heian-Kamakura warm stage and can be correlated to a Medieval Warm Period. After 580 cal yr PB, the lake gradually dried out and climatic signals could not be obtained from the declining lacustrine biological communities, but the increasing role of spruce and disappearance of the oak from the vegetation give evidences of the climate cooling that can be correlated with the LIA. The marine regression stages at the investigated site are identified forca6200–5900 (at the end of the middle Holocene transgression),ca5500–5100 (Middle Jomon regression or Kemigawa regression), andca1070–360 cal yr BP (at the end of Heian transgression). The lithological structure of sediments and the diatom compositions give evidences for the multiple tsunami events of different strengths in the Island. Most remarkable of them can be dated at aroundca7000, 6460, 5750, 4800, 950 cal yr BP. The new results help to understand the Holocene environmental history of the Southern Kurils as a part of the Kuril-Kamchatka and Aleutian Marginal Sea-Island Arc Systems in the North-Western Pacific region.