CLAY MINERALOGY AND DIAGENESIS OF K-BENTONITES OCCURRING IN THE DEVONIAN YILANLI
FORMATION FROM NORTH WESTERN ANATOLIA (BARTIN-ZONGULDAK)
Ü / nlü / ce, Ö / zge
M. Sc., Department of Geological Engineering
Supervisor: Prof. Dr. Asuman Gü / nal Tü / rkmenoglu
January 2013, 80 pages
Yellowish brown and gray-green colored K-bentonite horizons revealing thicknesses up to 60 cm are
exposed within the limestone-dolomitic limestone successions (Middle Devonian-Lower
Carboniferous Yilanli formation) deposited on a shallow marine carbonate platform at Zonguldak and
Bartin area in the western Black Sea region. In this study, bentonite samples collected from two
different locations / Gavurpinari quarry and Yilanli Burnu quarry are investigated by means of optical
microscopy, X-ray powder diffraction analyses (XRD), both scanning electron microscopy (SEM) and
energy dispersive X-ray (EDX) analysis, high resolution transmission electron microscopy (HR-TEM)
and inductively coupled plasma mass spectrometry (ICP-MS) in order to reveal their mineralogicalgeochemical
characteristics and understand their origin and evolution.
Illite is determined as the major phyllosilicate mineral in K-bentonites. Additionally, kaolinite and
illite-smectite mixed-layer clay minerals are also detected in some samples. As non-clay minerals
calcite, dolomite, quartz, gypsum, feldspar, pyrite and zircon are present in these K-bentonites.
Crystal-chemical characteristics (Kü / bler index-KI, intensity ratios (Ir), illite polytypes (%2M1), (d060) of
illite minerals from the two different sampling locations were investigated. Their KI values (for Yilanli
Burnu sampling location varying between 0.47-0.93 (with an average of 0.71 &Delta / ° / 2&theta / ) / for Gavurpinari
quarry sampling location varying between 0.69-0.77 (with an average of 0.72 &Delta / ° / 2&theta / )) / % of swelling
component (smectite-max 5%) and crystallite thickness (N=10-20 nm) indicate that these illites were
affected by high-grade diagenetic conditions. Similarly, illite polytype ratios (%2M1/(2M1+1Md))
range between 20-50% (with an average of 36%) for the Yilanli Burnu quarry samples, whereas,
these ratios are between 25-45% (with an average of 37%) for the Gavurpinari limestone quarry
samples. Illite polytpe data also supports a high-grade diagenetic origin possibility of K-bentonites.
Illite d060 values ranges between 1.491-1.503 Å / , (with an average of 1.499 Å / ) which reflect the
octahedral Mg+Fe compositions are varying between 0.27-0.51 and thus approach the ideal
muscovite-phengite values close to dioctahedral muscovite composition.
Based on the data obtained from this study, volcanic ash was firstly transformed into a smectitic I/S
mineral in early stages of sedimentation and burial diagenesis. This initial smectite was then be
transformed into a highly illitic I/S, and finally illite by diffusion of elements into and out of the bed,
during Devonian. Mineralogical-petrographical data points out that these K-bentonites evolved in a
high-grade diagenetic environment (approximately 100-150 ° / C) from the products of volcanic
eruptions having yet unknown source and distance during Middle-Late Devonian time.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12615587/index.pdf |
| Date | 01 February 2013 |
| Creators | Unluce, Ozge |
| Contributors | Gunal Turkmenoglu, Asuman |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for METU campus |
Page generated in 0.0059 seconds