Altered volcanic ash as an indicator of marine environment, reflecting pH and sedimentation rate - Example from the Ordovician Kinnekulle bed of Baltoscandia
Kiipli, Tarmo (Tallinn University of Technology. Institute of Geology)
Kiipli, Enli (Tallinn University of Technology. Institute of Geology)
Kallaste, Toivo (Tallinn University of Technology. Institute of Geology)
Hints, Rutt (University of Tartu. Institute of Geology)
Somelar, Peeter (University of Tartu. Institute of Geology)
Kirsimäe, Kalle (University of Tartu. Institute of Geology)

Date:	2007
Abstract:	The composition of altered volcanic ash of the Late Ordovician Kinnekulle bed was studied in geological sections of the Baltic Paleobasin. The composition of altered ash varies with paleosea depth from northern Estonia to Lithuania. The ash bed in shallow shelf limestones contains an association of illite-smectite (I-S) and K-feldspar, with the KO content ranging from 7. 5 to 15. 3%. The limestone in the transition zone between shallow- and deep-shelf environments contains I-S-dominated ash with KO content from 6. 0 to 7. 5%. In the deep-shelf marlstone and shale, the volcanic ash bed consists of I-S and kaolinite with a KO content ranging from 4. 1 to 6. 0%. This shows that authigenic silicates from volcanic ash were formed during the early sedimentary-diagenetic processes. The composition of the altered volcanic ash can be used as a paleoenvironmental indicator showing the pH of the seawater or porewater in sediments as well as the sedimentation rate.
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Baltoscandia ; K-bentonite ; Kinnekulle ; Marine Environment ; Ordovician ; Ph ; Sedimentation Rate ; Volcanic Ash
Published in:	Clays and Clay Minerals, Vol. 55, Núm. 2 (2007) , p. 177-188, ISSN 1552-8367

DOI: 10.1346/CCMN.2007.0550207

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