Geochemistry and correlation of volcanic ash beds from the Rootsikula Stage (Wenlock-Ludlow) in the eastern Baltic

摘要

Nine altered volcanic ash samples from the shoal and lagoonal sediments of the Rootsikula Stage (Wenlock-Ludlow boundary interval, Estonia) were analysed, compared and correlated with five samples of deep sea environments from Latvia. Volcanic ash correlations indicate that the Wenlock-Ludlow boundary correlates with the boundary of the Viita and Kuusnomme beds, i.e., it is significantly lower than proposed earlier. The distribution of chitinozoans supports this new correlation. Geochemical data indicate subalkaline source magma of volcanic ashes with potassium dominating over sodium.