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Diagenetic Transformation of Magnesite Pebbles and Cobbles to Sepiolite (Meerschaum) in the Miocene Eskişehir Lacustrine Basin, Turkey

Published online by Cambridge University Press:  28 February 2024

Ö. Işik Ece
Ö. Işik Ece*
Affiliation:
Istanbul Technical University, Mining Faculty, Mineralogy-Petrography Section, Maslak 80626 Istanbul, Turkey
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Abstract

Magnesite pebbles in Miocene lacustrine conglomerates in northwest Turkey have been partially to totally replaced by sepiolite. Only 5% of the magnesite pebbles have been converted to essentially pure sepiolite; the rest represent mixtures of magnesite and sepiolite. This process of sepiolitization is documented by X-ray diffraction (XRD), chemical, scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) techniques. These techniques show that the sepiolitization proceeds from the rim towards the core of the pebbles. The conglomerates, with pebbles of magnesite and ultramafic rocks, were deposited in a near-shore environment on the margin of a large Miocene lake with an ophiolitic substratum. The diagenetic transformation of magnesite to sepiolite is believed to have been caused by the interaction of mixed meteoric and lacustrine waters, which were undersaturated with respect to magnesite. The sepiolitization occurred during the highstands of the lake, when the near-shore conglomerates were flooded by the silica-rich lake waters. The pH of the water during the sepiolitization was probably on the order of 10.5–11.5. The sedimentary magnesite beds in the center of the Miocene basin show no sepiolitization, which is explained by the presence of pore water saturated with respect to magnesite.

The magnesite-sepiolite replacement process is chemically modeled as a 4-stage process from dimerization to polymerization.

Keywords

DiagenesisMagnesiteReplacementSepioliteTurkey
Type
Research Article
Information
Clays and Clay Minerals , Volume 46 , Issue 4 , August 1998 , pp. 436 - 445
Copyright
Copyright © 1998, The Clay Minerals Society

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References

Akıncı, Ö., 1967 Eskişehir I24-cl Paftasinin Jeolojisi ve Tabakalı Lületaşı Zuhurları (Geology of Map I24-C1 area and bedded sepiolite exposures in Eskişehir) MTA Dergisi 67 67–97.Google Scholar
Asutay, H.J. Küçükkayman, A. and Gözler, M.Z., 1989 Dağküplü (Eskişehir Kuzeyi) Ofiyolit Karmaşığının Stratigrafisi, Yapısal Konumu ve Kümülatlarìn Petrografisi (Stratigraphy and Structural Setting of Dağküplü Ophiolite Complex (North of Eskişehir) and Petrography of Cumulates) MTA Dergisi 109 1–8.Google Scholar
Badiozmani, K., 1973 The dorag dolomitization model—Application to the Middle Ordovician of Wisconsin J Sed Petrol 43 43–984.Google Scholar
Belzunce, M.S. Mendioroz, S. and Haber, J., 1991 Activation of sepiolite from Vallecas-Vicalvaro deposit, Spain: Its influence on surface and catalytic properties 71–76.Google Scholar
Burnett, W.C., 1977 Geochemistry and origin of phosphorite deposits from off Peru and Chile Geo Soc Am Bull 88 88–823 10.1130/0016-7606(1977)88<813:GAOOPD>2.0.CO;2.2.0.CO;2>CrossRefGoogle Scholar
Dandy, A.J. and Nadiye-Tabbiruka, M.S., 1982 Surface properties of sepiolite from Amboseli, Tanzania, and its catalytic activity for ethanol decomposition Clays Clay Miner 30 347–352 10.1346/CCMN.1982.0300505.CrossRefGoogle Scholar
Dandy, A.J., 1968 Sorption of vapours by sepiolite J Phys Chem 72 72–339 10.1021/j100847a065.CrossRefGoogle Scholar
Ece, O.I. and Çoban, F., 1994 Geology, occurrence and genesis of Eskişehir sepiolites, Turkey Clays Clay Miner 42 81–92 10.1346/CCMN.1994.0420111.CrossRefGoogle Scholar
Ece, O.I., 1990 Geochemistry and occurrence of authigenetic phosphate nodules from the Desmoinesian cyclic Excello epeiric sea of the midcontinent, USA Marine Petrol Geol 7 298–312 10.1016/0264-8172(90)90007-4.CrossRefGoogle Scholar
Gibbs, R.J., 1965 Error due to segregation in quantitative clay mineral X-ray diffraction mounting techniques Am Mineral 50 50–751.Google Scholar
Gibbs, R.J., 1968 Clay mounting techniques for X-ray diffraction analysis: A discussion J Sed Petrol 38 38–244 10.1306/74D71942-2B21-11D7-8648000102C1865D.CrossRefGoogle Scholar
Imai, N. Otsuka, R., Singer, A. and Galan, E., 1984 Sepiolite and palygorskite in Japan Palygorskite-sepiolite occurrences, genesis and uses. Dev In Sedimentol 37 Amsterdam Elsevier 211–232.Google Scholar
Jones, B.F. Galan, E. and Bailey, S.W., 1988 Sepiolite and palygorskite Hydrous phyllosilicates 631–674 10.1515/9781501508998-021.CrossRefGoogle Scholar
Knauth, L.P., 1979 A model for the origin of chert in limestone Geology 7 7–277 10.1130/0091-7613(1979)7<274:AMFTOO>2.0.CO;2.2.0.CO;2>CrossRefGoogle Scholar
Maliva, R.G. and Siever, R., 1989 Nodular chert formation in carbonate rocks J Geol 97 97–433 10.1086/629320.CrossRefGoogle Scholar
Neal, C. Stanger, G. and Drever, J.I., 1985 Past and present serpentinisation of ultramafic rocks; an example from the Semail Ophiolite Nappe of northern Oman The chemistry of weathering Holland D. Reidel 249–275 10.1007/978-94-009-5333-8_15.CrossRefGoogle Scholar
Riggs, S.R., 1979 Petrology of the tertiary phosphorite system of Florida Eco Geol 74 74–220.CrossRefGoogle Scholar
Serratoga, J.M., Mortland, M.M. and Farmer, V.C., 1979 Surface properties of fibrous clay minerals (palygorskite and sepiolite) Proc Int Clay Conf Amsterdam Elsevier 99–109.Google Scholar
Singer, A., 1989 Palygorskite and sepiolite group minerals Minerals in soil environments 829–872.CrossRefGoogle Scholar
Weaver, C.E., 1989 Clays, muds and shales Holland Elsevier.Google Scholar
Wey, R. and Siffert, B., 1961 Reaction de la Silice Monomoleculaire en Solution avec les ions Al, Mg. Genese et Synthese des Argiles Colloque Int Centre Natl Rech Sci 105 11–23.Google Scholar
Yeniyol, M., 1986 Vein-like sepiolite occurrence as a replacement of magnesite in Konya, Turkey Clays Clay Miner 34 353–356 10.1346/CCMN.1986.0340317.CrossRefGoogle Scholar
Yeniyol, M. Öztunalı, Ö, Gundoğdu, M.N. and Aksoy, H., 1985 Yunak Sepiolitinin Mineralojisi ve Oluşumu (Genesis and Mineralogy of Yunak Sepiolites) II. Ulusal Kil Sempozyumu 171–186.Google Scholar