Sedimentary evolution and environmental history of Lake Van (Turkey) over the past 600 000 years
Sedimentary evolution and environmental history of Lake Van (Turkey) over the past 600 000 years
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DOI：
10.1111/sed.12118
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发表时间：
2014-10
期刊：
影响因子：
3.5
通讯作者：
M. Stockhecke;M. Sturm;I. Brunner;H. Schmincke;M. Sumita;R. Kipfer;D. Cukur;O. Kwiecien;F. Anselmetti
中科院分区：
文献类型：
--
作者：
M. Stockhecke;M. Sturm;I. Brunner;H. Schmincke;M. Sumita;R. Kipfer;D. Cukur;O. Kwiecien;F. Anselmetti
对土耳其东部凡湖的岩石地层框架进行了系统分析，记录了该湖在过去约 60 万年的沉积演化和环境历史。凡湖 219 m 长钻芯的岩石地层学和化学地层学有助于将全球气候振荡与构造和火山活动引起的局部因素分开。年龄模型是根据化学和岩性特征的气候地层排列建立的，并通过 40Ar/39Ar 年龄进行验证。钻探层序由约 76% 的湖相碳质粘土粉砂、约 2% 的河流沉积物、约 17% 的火山碎屑沉积物和 5% 的间隙组成。从河流沉积物和事件沉积物中分离出六种湖泊岩型，例如火山碎屑岩（约 300 层）和分级岩层（约 375 层），并记录了它们的沉积环境。这些岩型是： (i) 分级床经常夹有变化的粘土粉砂，反映了湖水终止期间水位上升； (ii) 变化的粘土粉砂反映了强烈的季节性和湖内缺氧边界，例如间冰期/间冰期期间的湖面高位； (iii) 富含 CaCO3 的带状沉积物，代表含氧-缺氧边界的降低，例如，冰川初期湖泊水位下降； (iv) 贫 CaCO3 的带状和斑驳的粘土质粉砂反映了靠近沉积物-水界面的缺氧边界，例如冰川/体育场期间的湖面低位； (v) 硅藻泥是在湖泊形成初期作为淡水系统沉积的； (vi) 表明湖盆最初发生洪水的河流沙子和砾石。岩性 (i) 至 (iv) 的重现遵循过去五个冰期/间冰期旋回。 20 m 厚的扰动单元反映了凡湖约 414 ka bp 的主要构造活动区间。尽管构造和火山活动等当地环境过程影响了沉积作用，但岩石地层格局和有机质含量清楚地反映了过去的全球气候变化，使凡湖成为对过去60万年区域气候重建具有前所未有的敏感性的杰出陆地档案。
The lithostratigraphic framework of Lake Van, eastern Turkey, has been systematically analysed to document the sedimentary evolution and the environmental history of the lake during the past ca 600 000 years. The lithostratigraphy and chemostratigraphy of a 219 m long drill core from Lake Van serve to separate global climate oscillations from local factors caused by tectonic and volcanic activity. An age model was established based on the climatostratigraphic alignment of chemical and lithological signatures, validated by 40Ar/39Ar ages. The drilled sequence consists of ca 76% lacustrine carbonaceous clayey silt, ca 2% fluvial deposits, ca 17% volcaniclastic deposits and 5% gaps. Six lacustrine lithotypes were separated from the fluvial and event deposits, such as volcaniclastics (ca 300 layers) and graded beds (ca 375 layers), and their depositional environments are documented. These lithotypes are: (i) graded beds frequently intercalated with varved clayey silts reflecting rising lake levels during the terminations; (ii) varved clayey silts reflecting strong seasonality and an intralake oxic–anoxic boundary, for example, lake‐level highstands during interglacials/interstadials; (iii) CaCO3‐rich banded sediments which are representative of a lowering of the oxic–anoxic boundary, for example, lake level decreases during glacial inceptions; (iv) CaCO3‐poor banded and mottled clayey silts reflecting an oxic–anoxic boundary close to the sediment–water interface, for example, lake‐level lowstands during glacials/stadials; (v) diatomaceous muds were deposited during the early beginning of the lake as a fresh water system; and (vi) fluvial sands and gravels indicating the initial flooding of the lake basin. The recurrence of lithologies (i) to (iv) follows the past five glacial/interglacial cycles. A 20 m thick disturbed unit reflects an interval of major tectonic activity in Lake Van at ca 414 ka bp. Although local environmental processes such as tectonic and volcanic activity influenced sedimentation, the lithostratigraphic pattern and organic matter content clearly reflect past global climate changes, making Lake Van an outstanding terrestrial archive of unprecedented sensitivity for the reconstruction of the regional climate over the last 600 000 years.