Geological, mineralogical and geochemical characteristics of Mississippian K-bentonites from southern Turkey: A correlation with coeval tephras from Gondwana-derived terranes

2021-09-01
Five thin (5–15 cm) and yellowish green tephra (K-bentonite) layers are exposed along two sections in the south of Akşehir (Konya, southern Turkey) within the Early Carboniferous (Mississippian) red dolomite-dolomitic limestone succession of the Sultandağ Unit in the central Tauride Belt. K-bentonites exhibit typical porphyritic texture with euhedral plagioclase phenocrysts replaced by fine-grained white K-micas and sparry dolomite crystals. The intensively sericitized volcanic matrix has vitrophyric texture and contains hydroxidized euhedral pyrite crystals. Illite is the only clay mineral in all K-bentonite samples. Non-clay minerals are dolomite, calcite, quartz, pyrite, rutile and zircon. Illites have sheet-like flakes (1–4 μm sizes) showing well-developed orientations and partly slaty cleavage. Illite Kübler index values (KI, Δ°2θ) of K-bentonites reflect high-grade diagenetic to anchizonal conditions indicating temperatures that reached up to 200 °C. Illite d060 values (1.4990–1.5007 Å) corresponding to dioctahedral composition display differences in coexisting slates and shales of the same age. Illite polytypes are characterized by the association of 2M1, 1M and 1Md. The presence of 1M illites is indicative of a volcanic (tephra) origin. Immobile element compositions suggest that tephras have been derived from trachyandesitic volcanism. K-bentonites exhibit some differences from the coeval pelitic occurrences in the Hadim-Bozkır areas, S Turkey, and the Late Devonian-Early Carboniferous K-bentonites in Bartın and Zonguldak areas of the Istanbul-Zonguldak Terrane, NW Turkey. A geochemical evolution of the studied K-bentonites suggests that they were possibly originated from the Early Carboniferous (Mississippian) intra-continental back-arc magmatism at the northern margin of Gondwana-derived Tauride-Anatolide microplate.
Journal of African Earth Sciences

Suggestions

GEOLOGICAL AND GEOCHEMICAL EVIDENCE FOR A LATE CRETACEOUS CONTINENTAL ARC IN THE CENTRAL PONTIDES, NORTHERN TURKEY
Ellero, Alessandro; Ottria, Giuseppe; Sayıt, Kaan; Catanzariti, Rita; Frassi, Chiara; Göncüoğlu, Mehmet Cemal; Marroni, Michele; Pandolfi, Luca (2015-01-01)
In the Central Pontides (Northern Turkey), south of Tosya, a tectonic unit consisting of not-metamorphic volcanic rocks and overlying sedimentary succession is exposed inside a fault-bounded elongated block. It is restrained within a wide shear zone, where the Intra-Pontide suture zone, the Sakarya terrane and the Izmir-Ankara-Erzincan suture zone are juxtaposed as result of strike-slip activity of the North Anatolian shear zone. The volcanic rocks are mainly basalts and basaltic andesites (with their pyroc...
GEOCHEMISTRY AND PETROGENESIS OF THE ARC-RELATED KÖSDAĞ METAVOLCANICS, SOUTHERN CENTRAL PONTIDES, NORTHERN TURKEY
Berber, Faruk; Sayıt, Kaan; Department of Geological Engineering (2021-12-27)
The Kösdağ Metavolcanics (KM) in the southern Central Pontides crops out between the Izmir-Ankara-Erzincan Suture Zone (IAESZ) in the south and the Sakarya Composite Terrane in the north. The unit is represented by a low-grade metamorphic assemblage including meta-basics, meta-intermediates, and meta-felsics, interlayered with recrystallized limestone, mudstone, and chert. While the unit is bounded to the north by the North Anatolian Fault Zone (NAFZ), the Dikmen Formation stratigraphically overlie the unit...
GEOLOGY AND CHEMICAL VARIATIONS IN TOURMALINE FROM THE QUARTZ-TOURMALINE BRECCIAS WITHIN THE KERKENEZ GRANITE-MONZONITE MASSIF, CENTRAL ANATOLIAN CRYSTALLINE COMPLEX, TURKEY
Demirel, Serhat; Göncüoğlu, Mehmet Cemal; Topuz, Gueltekin; IŞIK, VEYSEL (2009-08-01)
A hydrothermal breccia zone 6 km long and 2 km wide, crossed by quartz-tourmaline veins, occurs to the south of the Late Cretaceous Kerkenez granite-monzonite massif in the northern part of the Central Anatolian Crystalline Complex, Yozgat, Turkey. This breccia zone is characterized by numerous veins, a few millimeters to 1 meter in width, and display typical microtectonic features of multiple brecciation. Trace amounts of albite, K-feldspar, epidote, muscovite and rutile are associated with quartz and tour...
Geological features and geochemical characteristics of Late Devonian-Early Carboniferous K-bentonites from northwestern Turkey
Göncüoğlu, Mehmet Cemal; Günal Türkmenoğlu, Asuman; OKUYUCU, CENGİZ; Yılmaz, İsmail Ömer (2016-09-01)
Newly discovered K-bentonite beds, interstratified with limestones/dolomitic limestones of the Upper Devonian-Lower Carboniferous Yilanli Formation, are exposed in the northwestern Black Sea region of Turkey, around Zonguldak and Bartin. K-bentonite samples collected from four different locations: the Gavurpinari and Yilanli Burnu quarries from the Bartin area, the Cimsir Cukurlari quarry from the Sapca area, and the Gudullu and Gokgol highway tunnel section near Zonguldak city were investigated using optic...
Clay mineralogy, chemistry, and diagenesis of Late Devonian K-bentonite occurrences in northwestern Turkey
Günal Türkmenoğlu, Asuman; BOZKAYA, ÖMER; Göncüoğlu, Mehmet Cemal; Unluce, Ozge; Yılmaz, İsmail Ömer; OKUYUCU, CENGİZ (2015-01-01)
Thin beds of tephra (K-bentonites) formed by the diagenesis of volcanic ash are exposed within the limestone-dolomitic limestone successions of the Yilanli formation at Zonguldak and Bartin in northwestern Turkey. They were deposited on the Middle Devonian-Lower Carboniferous shallow carbonate platform of the Zonguldak terrane. In this study, K-bentonite samples collected from Gavurpinari and Yilanli Burnu limestone quarries are investigated in order to reveal their mineralogical and geochemical characteris...
Citation Formats
Ö. Bozkaya, A. Günal Türkmenoğlu, M. C. Göncüoğlu, and C. Okuyucu, “Geological, mineralogical and geochemical characteristics of Mississippian K-bentonites from southern Turkey: A correlation with coeval tephras from Gondwana-derived terranes,” Journal of African Earth Sciences, pp. 0–0, 2021, Accessed: 00, 2021. [Online]. Available: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85106325300&origin=inward.