Current IF 1.500
Latest issue (RSS 2.0)
Contact Editorial Office at
Bulletin of Geosciences
Published by ©
Czech Geological Survey,
W. Bohemia Museum Pilsen
ISSN: 1802-8225 (online),
The Geniai Tuff in the southern East Baltic area - a new correlation tool near the Aeronian/Telychian stage boundary, Llandovery, Silurian
Published in: Bulletin of Geosciences, volume 87, issue 4; pages: 695 - 704; Received 25 August 2011; Accepted in revised form 8 December 2011; Online 23 May 2012
Keywords: REE, goyazite, florencite, K-bentonite, Silurian, East Baltic,
AbstractIn three drill cores in Latvia and Lithuania a thin (1 cm thick) altered volcanic ash bed with high concentrations of phosphorus (up to 3%), cerium (1%), lanthanum (0.5%) and strontium (2.5%), has been found close to the Aeronian/Telychian boundary (Llandovery, Silurian, ca 438 Ma). Small, millimetre-thick lenses within the ash bed contain up to 12% P and Sr, up to 6% Ce and 3% La. These elements occur as a solid solution of goyazite-florencite mineral. Additionally, authigenic K-feldspar and kaolinite occur in this ash bed. The high concentrations of REE elements, strontium and phosphorus suggest a carbonatite source magma, but the strontium isotope ratio contradicts that origin. Such a unique composition in a volcanic ash layer is a good basis for using it as a marker horizon for correlation of sections.
BATCHELOR, R.A. & WEIR, J.A. 1988. Metabentonite geochemistry: magmatic cycles and graptolite extinctions at Dob’s Linn, southern Scotland. Transactions of the Royal Society of Edinburgh, Earth Sciences 79, 19–41.
BERGSTRÖM, S.M., HUFF, W.D., KOLATA, D.R. & BAUERT, H. 1995. Nomenclature, stratigraphy, chemical fingerprinting and areal distribution of some Middle Ordovician K-bentonites in Baltoscandia. GFF 117, 1–13.
MCLENNAN, S.M. 1989. Rare earth elements in sedimentary rocks: influence of provenance and sedimentary processes, 169–200. In LIPIN, B.R. & MCKAY, G.A. (eds) Geochemistry and Mineralogy of Rare Earth Elements. Reviews in Mineralogy 21.
RAY, D.C. 2007. The correlation of Lower Wenlock Series (Silurian) bentonites from the Lower Hill Farm and Eastnor Park boreholes, Midland Platform, England. Proceedings of the Geologists’ Association 118, 175–185.