Composition and correlation of volcanic ash beds of Silurian age from the eastern Baltic
Composition and correlation of volcanic ash beds of Silurian age from the eastern Baltic
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DOI：
10.1017/s0016756810000294
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发表时间：
2010-04
影响因子：
2.3
通讯作者：
T. Kiipli;T. Kallaste;V. Nestor
中科院分区：
文献类型：
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作者：
T. Kiipli;T. Kallaste;V. Nestor
波罗的海东部火山灰层透长石成分和整体地球化学特征表明，志留纪波罗的海板块边缘附近的火山活动具有亚碱性性质。文洛克的几个钙镁石包括一个以前未知的透长石，Na+Ca成分为48至58摩尔%。与早期的Telychian火山作用相反，富钠透长石出现在灰层中，灰层起源于相对中等演化的英安质岩浆。研究材料从两个钻芯与以前的研究相结合，使生产的49个火山喷发层的更完整的列表，在东波罗的海的下部到中部文洛克。这一最新的透长石组合物特征的钙长石列表为北方欧洲未来的综合生物和化学地层对比奠定了良好的基础。
Abstract Sanidine composition and bulk geochemistry of volcanic ash beds from the East Baltic indicate the subalkaline nature of the volcanism near the margins of the Baltica plate during the Silurian. Several bentonites in the Wenlock include a previously unknown sanidine with 48 to 58 mol % of the Na+Ca component. In contrast to the earlier Telychian volcanism, sodium-rich sanidine occurs in ash beds which originate from relatively moderately evolved dacitic magma. The studied material from two drill cores integrated with previous research enables production of a more complete list of 49 volcanic eruption layers for the lower to middle Wenlock in the East Baltic. This updated list of bentonites characterized by their sanidine compositions forms a good basis for future integrated bio- and chemostratigraphic correlations in northern Europe.