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From a large basin to a small lake: Siliceous microfossils stratigraphy of the isolation basins on Big Solovetskiy Island (the White Sea, NW Russia) and its implication for paleoreconstructions
Quaternary International ( IF 1.9 ) Pub Date : 2021-07-13 , DOI: 10.1016/j.quaint.2021.07.007
A.V. Ludikova 1 , D.A. Subetto 2 , D.D. Kuznetsov 1 , T.V. Sapelko 1
Affiliation  

This paper discusses the results of siliceous microfossils studies performed in a “staircase” of four isolation basins (33.7 m–2.9 m a.s.l.) on Big Solovetskiy Island (Solovki Archipelago, the White Sea). Diatoms were used as a primary group for paleoinferences, while chrysophyte cysts and sponge spicules also demonstrated high indicative potential. In all study lakes, the siliceous microfossils stratigraphy revealed three main stages of their evolution, i.e. large-basin, transitional and small-lake stages, each characterized by certain composition of the diatom assemblages and floristic diversity, relative abundances of chrysophyte cysts and sponge spicules, and siliceous microfossils concentrations. In the uppermost lake, glaciolacustrine environments unfavorable for aquatic biota existed during the large-basin stage. The proglacial lake stage terminated prior to ca. 10.4 cal ka BP, followed by a (semi)terrestrial episode before the transition to small-lake environments. In the other three lakes, marine environments were inferred at the earlier stage, characterized by the predominance of marine and brackish-marine diatoms, increased proportions of sponge spicules and low “cysts to diatoms” ratio. At the transitional marine-freshwater stage, mass growth of small fragilarioid diatoms and decreased abundances of spicules indicated unstable environments, while increased proportions of cysts pointed to progressive freshening of the basins. The duration of the marine-freshwater transition expectedly prolonged from ca. 200 yr in the upper basin (16.6 m a.s.l) to ca. 500 yr in the lowermost lake (2.9 m a.s.l.). The isolation from the sea took place between ca. 6.3 and 1.4 cal ka BP. At the small-lake stage, siliceous microfossils stratigraphies reflected local specifics of the basins and their catchments. We argue that besides traditionally used diatom data, relative and absolute abundances of siliceous microfossils also possess high indicative value for isolation basin studies. Our study demonstrated that marine waters on Big Solovetskiy Island never reached ca. 34 m a.s.l. during the Holocene, unlike the western coast of the Onega Bay where the Preboreal marine intrusion was recorded even at higher elevated localities. Different rates and amplitudes of shoreline displacement are thus suggested for the inner and outer parts of the Onega Bay. During the mid-Holocene Tapes transgression, before ca. 6.3 cal ka BP, the relative sea level on Big Solovetskiy Island exceeded 17 m a.s.l. The average estimated rates of the shoreline retreat during the second half of the Holocene gradually decreased from 0.28 cm year−1 to 0.2 cm year−1, indicating slowed isostatic uplift.



中文翻译:

从大盆地到小湖:大索洛维茨基岛(白海,俄罗斯西北部)隔离盆地的硅质微化石地层学及其对古岩石构造的意义

本文讨论了在大索洛维茨基岛(白海索洛维基群岛)的四个隔离盆地(33.7 m–2.9 m asl)的“阶梯”中进行的硅质微化石研究结果。硅藻被用作古推断的主要群体,而金藻囊肿和海绵骨针也表现出很高的指示潜力。在所有研究湖泊中,硅质微化石地层学揭示了其演化的三个主要阶段,即大盆地阶段、过渡阶段和小湖泊阶段,每个阶段都以特定的硅藻组合组成为特征,植物区系多样性、金藻囊肿和海绵骨针的相对丰度以及硅质微化石浓度。最上层湖泊在大盆地阶段存在不利于水生生物群落的冰湖环境。前冰川湖阶段在 ca 之前终止。10.4 cal ka BP,随后是(半)陆地事件,然后过渡到小湖泊环境。其他三个湖泊早期推测为海洋环境,以海洋和微咸水硅藻为主,海绵骨针比例增加,“胞囊硅藻”比低。在海洋-淡水过渡阶段,小型脆弱硅藻的大量生长和针状体丰度的减少表明环境不稳定,而囊肿比例的增加表明盆地逐渐变新鲜。海洋 - 淡水过渡的持续时间预计从大约延长。200 年在上盆地 (16.6 m asl) 到 ca。500 年在最低的湖 (2.9 m asl)。与大海的隔离发生在大约之间。6.3 和 1.4 cal ka BP。在小湖阶段,硅质微化石地层反映了盆地及其流域的局部特征。我们认为,除了传统上使用的硅藻数据外,硅质微化石的相对和绝对丰度也对隔离盆地研究具有很高的指示价值。我们的研究表明,大 Solovetskiy 岛的海水从未达到约 100 米。34 m asl 期间 200 年在上盆地 (16.6 m asl) 到 ca。500 年在最低的湖 (2.9 m asl)。与大海的隔离发生在大约之间。6.3 和 1.4 cal ka BP。在小湖阶段,硅质微化石地层反映了盆地及其流域的局部特征。我们认为,除了传统上使用的硅藻数据外,硅质微化石的相对和绝对丰度也对隔离盆地研究具有很高的指示价值。我们的研究表明,大 Solovetskiy 岛的海水从未达到约 100 米。34 m asl 期间 200 年在上盆地 (16.6 m asl) 到 ca。500 年在最低的湖 (2.9 m asl)。与大海的隔离发生在大约之间。6.3 和 1.4 cal ka BP。在小湖阶段,硅质微化石地层反映了盆地及其流域的局部特征。我们认为,除了传统上使用的硅藻数据外,硅质微化石的相对和绝对丰度也对隔离盆地研究具有很高的指示价值。我们的研究表明,大 Solovetskiy 岛的海水从未达到约 100 米。34 m asl 期间 我们认为,除了传统上使用的硅藻数据外,硅质微化石的相对和绝对丰度也对隔离盆地研究具有很高的指示价值。我们的研究表明,大 Solovetskiy 岛的海水从未达到约 100 米。34 m asl 期间 我们认为,除了传统上使用的硅藻数据外,硅质微化石的相对和绝对丰度也对隔离盆地研究具有很高的指示价值。我们的研究表明,大 Solovetskiy 岛的海水从未达到约 100 米。34 m asl 期间全新世,不像奥涅加湾的西海岸,那里甚至在更高的地方也记录了前北方海洋入侵。因此,奥涅加湾的内部和外部建议采用不同的海岸线位移速率和幅度。在全新世中期海侵期间,大约在。6.3 cal ka BP,Big Solovetskiy Island 的相对海平面超过 17 m asl 全新世后半期海岸线后退的平均估计速率从 0.28 cm year -1逐渐下降到 0.2 cm year -1,表明均衡减慢提升。

更新日期:2021-07-13
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