Millennial-scale vegetation changes in the north-eastern Russian Arctic during the Pliocene/Pleistocene transition (2.7–2.5 Ma) inferred from the pollen record of Lake El’gygytgyn
Millennial-scale vegetation changes in the north-eastern Russian Arctic during the Pliocene/Pleistocene transition (2.7–2.5 Ma) inferred from the pollen record of Lake El’gygytgyn
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DOI：
10.1016/j.quascirev.2016.03.030
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发表时间：
2016-09
影响因子：
4
通讯作者：
Andrei A. Andreev;P. Tarasov;V. Wennrich;M. Melles
中科院分区：
文献类型：
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作者：
Andrei A. Andreev;P. Tarasov;V. Wennrich;M. Melles
El'gygytgyn湖（67°30′N，172°05′E）的沉积记录跨越了过去3.6 Ma，为定性和定量重建陆地北极的区域古环境历史提供了独特的机会。对上新世晚期和更新世早期（约1000年）积累的沉积物进行了千年尺度的花粉研究。2.7到2.5 Ma），表明在这一过渡时期，轨道驱动的植被和气候变化。花粉光谱显示，在上新世/更新世的边界，是一个显着的植被转移，但是，延迟了几千年相比，湖泊的反应。在2.70-2.68 Ma，El'gygytgyn湖的植被主要为落叶松林，林下有一些灌木松树、灌木桤木和矮桦。在海洋同位素阶段G3和G1，约。2.665-2.647 Ma和2.625-2.617 Ma，当地落叶松松林中生长了一些云杉，表明气候条件相对温暖。在更新世开始时，大约2.588 Ma，一个突出的气候恶化导致从落叶松为主的森林主要是无树的草原和苔原样栖息地的变化。在CA之间。2.56-2.53 Ma，该地区针叶树（主要是松树和落叶松，但也可能是云杉）的出现增加，反映了气候的一些改善。在2.53 Ma之后，相对寒冷和干燥的气候再次占主导地位，导致开放的草原和灌木环境，随后在约2.53 Ma之间气候改善。2.510和2.495 Ma，当花粉组合表明，落叶松林与矮桦树和灌木桤木仍然生长在湖泊附近。绿色藻类群落（葡萄藻属）和接合孢囊在2.691-2.689、2.679-2.677、2.601-2.594、2.564-2.545和2.532-2.510 Ma的含量增加表明浅水环境的扩展很可能是由于湖平面下降。这些事件发生的同时，干旱的气候条件推断草原栖息地与Artemisia和其他草药的广泛分布。
The sediment record of Lake El’gygytgyn (67°30′N, 172°05′E) spans the past 3.6 Ma and provides unique opportunities for qualitative and quantitative reconstructions of the regional paleoenvironmental history of the terrestrial Arctic. Millennial-scale pollen studies of the sediments that accumulated during the Late Pliocene and Early Pleistocene (ca. 2.7 to 2.5 Ma) demonstrate orbitally-driven vegetation and climate changes during this transitional interval. Pollen spectra show a significant vegetation shift at the Pliocene/Pleistocene boundary that is, however, delayed by a few thousand years compared to lacustrine response. About 2.70–2.68 Ma the vegetation at Lake El’gygytgyn, currently a tundra area was mostly dominated by larch forests with some shrub pine, shrub alder and dwarf birch in understory. During the marine isotope stages G3 and G1, ca. 2.665–2.647 and 2.625–2.617 Ma, some spruce trees grew in the local larch-pine forests, pointing to relatively warm climate conditions. At the beginning of the Pleistocene, around 2.588 Ma, a prominent climatic deterioration led to a change from larch-dominated forests to predominantly treeless steppe- and tundra-like habitats. Between ca. 2.56–2.53 Ma some climate amelioration is reflected by the higher presence of coniferous taxa (mostly pine and larch, but probably also spruce) in the area. After 2.53 Ma a relatively cold and dry climate became dominant again, leading to open steppe-like and shrubby environments followed by climate amelioration between ca. 2.510 and 2.495 Ma, when pollen assemblages show that larch forests with dwarf birch and shrub alder still grew in the lake’s vicinity. Increased contents of green algae colonies (Botryococcus) remains andZygnemacysts around 2.691–2.689, 2.679–2.677, 2.601–2.594, 2.564–2.545, and 2.532–2.510 Ma suggest a spread of shallow-water environments most likely due to a lake-level lowering. These events occurred simultaneously with dry climate conditions inferred from broad distribution of steppe habitats withArtemisiaand other herbs.