Use of immobile trace elements for the correlation of Telychian bentonites on Saaremaa Island, Estonia, and mapping of volcanic ash clouds

Abstract

Thirty suspected altered volcanic ash (bentonite) samples from the Nässumaa-825 and Orissaare-859 sections were analysed by the X-ray fluorescence method. Twenty of these samples revealed chemical signs of pure volcanogenic material, one was of mixed terrigenous-volcanogenic origin, and nine were classified as terrigenous claystones. Twenty of the bentonites were correlated, with variable confidence, with bentonites from earlier studied sections; one sample represents a formerly unknown eruption. New and earlier published bentonite correlations were used for tracing the diachronous nature of the Rumba-Velise formations boundary and for composing new isopach schemes of six Telychian bentonites.

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

“…For calibration and quality control reference materials from France (Govindaraju 1995) and Estonia (Kiipli et al 2000) were used. The accuracy of the method is described in Kiipli et al (2008b).…”

“…For identification of a particular eruption bed the composition of apatite (Ray 2007;Carey et al 2009), biotite (Batchelor 2003) and sanidine phenocrysts (Kiipli & Kallaste 2002), the specific shape of phenocrysts (Kiipli et al 2009) and immobile trace elements (Huff et al 1998;Kiipli et al 2008b) have been used. The phenocryst and bulk geochemistry of bentonites provides also an opportunity to interpret magma geochemistry and evolution of tectonomagmatic processes in source areas (Histon et al 2007;Kiipli et al 2008dKiipli et al , 2010a.…”

Internal stratification of two thick Ordovician bentonites of Estonia: deciphering primary magmatic, sedimentary, environmental and diagenetic signatures

“…In our previous analyses on the East Baltic materials we have considered Ti, Zr, Th and Nb as immobile (Kiipli et al 2008b(Kiipli et al , 2013. The present data from the BII Bentonite, where the maximum Nb content significantly exceeding common values in the silicate parts of the host rock occurs directly below the bentonite, indicate small-scale mobility of this element during the conversion of volcanic ash in lime sediment.…”

Geochemical variations within the mid-Silurian Grötlingbo Bentonite (Gotland, Sweden): discriminating between magmatic composition, ash transport fractionation and diagenetic effects

“…For regional or intercontinental correlation of bentonites, mostly immobile elements Al, Ti, Zr, Nb and Th are useful (Kiipli et al 2008b). Within the Grötlingbo Bentonite, the concentration of Zr in the lower part is twice higher than in the rest of the bentonite.…”

“…Various methods for such fingerprinting exist, and the composition of magmatic phenocrysts apatite (Batchelor et al 1995;Ray 2007;Sell & Samson 2011), biotite (Batchelor 2003) and sanidine (Kiipli & Kallaste 2002) and trace element characteristics (Batchelor & Jeppson 1999;Batchelor & Evans 2000;Huff et al 2000;Inanli et al 2009;Kiipli et al 2008b) have all been used for characterisation and interpretation of ash beds. The vertical chemical and mineralogical composition of individual ash beds is not homogeneous, but varies due to the successive change in magma composition during long-lasting eruptions and due to physical fractionation of ash in air transport and during settling in water basins (Fisher & Schmincke 1984).…”