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Geology and conditions of formation of the zeolite-bearing deposits southeast of Ankara (central Turkey)

Muazzez Celik Karakaya, Necati Karakaya and Fuat Yavuz
Geology and conditions of formation of the zeolite-bearing deposits southeast of Ankara (central Turkey)
Clays and Clay Minerals (April 2015) 63 (2): 85-109


The pyroclastic sediments studied here contained varied amounts of zeolite and were formed in the saline alkaline Tuzgolu Basin following the alteration of dacitic volcanic materials during the Early to Late Miocene. The present study focused on the geological-geochemical properties of the zeolites and describes their formation. Mineralogical and chemical compositions were determined by X-ray diffraction, scanning electron microscopy, optical microscopy, and inductively coupled plasma mass spectrometry. Results indicated that the zeolitic tuffs consisted mainly of heulandite/clinoptilolite (Hul/Cpt), chabazite, erionite, and analcime associated with smectite. Smectite, calcite, and dolomite are abundant in the clay and carbonate layers which alternate with the zeolitic tuffs. K-feldspar, gypsum, and hexahydrite (MgSO (sub 4) .6H (sub 2) O) were also found in some altered tuffs and clay-marl layers as accessory minerals. The zeolite and other authigenic minerals showed weak stratigraphic zonation. Some vitric tuff layers contained no zeolite minerals and others were found to consist of almost pure Hul/Cpt and chabazite layers with economic potential. The rare earth elements (REE), large ion lithophile elements (LILE), and high-field strength elements (HFSE) in the Hul/Cpt-rich tuffs and vitric tuffs were enriched or depleted relative to the precursor rock, while many major elements were slightly or significantly depleted in all zeolitic tuffs. The amounts of REE in the chabazite- and erionite-rich tuffs were generally smaller than those in the precursor rock. The middle and heavy REE (MREE and HREE, respectively) were abundant in the Hul/Cpt-rich tuffs, tuffs, and smectitic bentonites. Chondrite-normalized REE values of the sample groups are characterized by sub-parallel patterns with enrichment in LREE relative to HREE. The mineral assemblages and geological setting indicated that zeolite diagenesis occurred in a saline-alkaline basin. The delta (super 18) O and delta D compositions of the Hul/Cpt, chabazite, and smectite indicated that the minerals formed at low to moderate temperatures and that some of the zeolitization occurred due to diagenetic alteration under closed-system conditions that varied according to the nature of the basin and with the composition and physical properties of the volcanic materials.

ISSN: 0009-8604
EISSN: 1552-8367
Serial Title: Clays and Clay Minerals
Serial Volume: 63
Serial Issue: 2
Title: Geology and conditions of formation of the zeolite-bearing deposits southeast of Ankara (central Turkey)
Affiliation: Selcuk Universitesi Muhendislik Fakultesi, Konya, Turkey
Pages: 85-109
Published: 201504
Text Language: English
Publisher: Clay Minerals Society, Chantilly, VA, United States
References: 72
Accession Number: 2016-001985
Categories: Economic geology, geology of nonmetal depositsSedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables, sketch maps
N39°55'00" - N39°55'00", E32°49'60" - E32°49'60"
Secondary Affiliation: Istanbul Teknik Universitesi, TUR, Turkey
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 201601
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