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Composition and correlation of volcanic ash beds of Silurian age from the eastern Baltic

2010; Cambridge University Press; Volume: 147; Issue: 6 Linguagem: Inglês

10.1017/s0016756810000294

1469-5081

Tarmo Kiipli, T Kallaste, Viiu Nestor,

Hydrocarbon exploration and reservoir analysis

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.