Genesis of smectite in siliciclastics and pyroclastics of the Eocene Islambeyli Formation in the Lalapasa region, NW Thrace, Turkey

B. Ekinci Sans, F. Esenli, S. Kadir, W. C. Elliott

Araştırma sonucu: ???type-name???Makalebilirkişi

24 Atıf (Scopus)

Özet

The Eocene Islambeyli Formation in the Lalapasą region (NW Thrace, Turkey) consists predominantly of siliciclastic clayey clastics at the bottom and of claystone, tuff and tuffaceous claystone/sandstone/limestone in the middle and uppermost parts of this formation. Some tuff-tuffaceous beds of the middle-upper parts of the formation are economically viable bentonite depoits. The Islambeyli Formation exhibits vertical variations in the mineralogy, elemental compositions, and smectite-forming processes. Smectite was formed by weathering and diagenetic processes in the fluvial-shore environments in the lower part and by diagenetic alteration in a shallow-marine environment in the middle-upper parts of the formation. Ca-smectite flakes were formed by two processes: direct precipitation; and by means of a dissolution-precipitation mechanism from feldspar and mica. Dissolution-precipitation was most prevalent in the siliciclastic lower part of the formation. The amounts of Al, Fe, Mg and Ca required to form smectite and accessory illite were supplied mainly from the alteration of feldspars, mica and glass shards. The origin of smectite can also be explained by the inferred solution compositions given the parent phases in this formation, and the devitrification of glass shards in pyroclastic-rich middle-upper parts of the formation. In the upper beds, the observed decrease of K and Fe in the smectite structure coincided with both the increase in the amount of smectite and the increase in solution pH suggesting that precipitation of smectite developed over a prolonged period and under arid conditions.

Orijinal dilİngilizce
Sayfa (başlangıç-bitiş)459-483
Sayfa sayısı25
DergiClay Minerals
Hacim50
Basın numarası4
DOI'lar
Yayın durumuYayınlandı - 1 Eyl 2015

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Publisher Copyright:
© 2015 Mineralogical Society.

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