Coal quality, mineralogy, petrography, and geochemistry of the high-strontium Bozburun lignite (Malatya, eastern Türkiye)

The Bozburun coalfield hosts a late Miocene 1.1 m thick coal seam. This study aims to determine coal quality, mineralogy, petrography and geochemistry, and controlling factors of elemental enrichments. The coals are generally black and greyish black in colour, and the low part of the seam commonly includes fossil shell remains. The ash yield displays a decreasing trend towards the upper part of the seam; in turn, gross calorific and total C values increase upwards. The total S content being generally higher than 5% (on dry basis), displays an increasing trend towards the upper part. In the entire seam, huminite is the most common maceral group, while inertinite and liptinite display variable proportions. The identified minerals by XRD are mainly quartz, clay minerals, calcite, pyrite, and aragonite (in fossil shell remains-bearing samples), whereas feldspars and marcasite determined in a few samples. Furthermore, in the coal samples, celestine and barite were identified by SEM-EDX. This study indicates that precipitation of celestine and Sr-bearing barite grains during diagenetic stage and Sr-uptake by mollusc within the palaeomire caused Sr enrichment in the entire seam. Overall, the water influx and redox conditions controlled the mineralogical and the elemental compositions of the coal seam

Vitrinite reflectances and mineralogy of coal clasts in the Late Carboniferous sequences in the two-deep research wells from the Kozlu coalfield (Zonguldak Basin, NW Türkiye)

Fifty-four coal clast samples in the siliciclastic rocks (e.g., sandstone and conglomerate) were collected from cores of two-deep research wells (K20H and K20K) drilled at the Kozlu coalfield in Zonguldak Basin, and for the first time, they were evaluated using mineralogy by XRD and SEMEDX and random vitrinite reflectance (%Rr) measurements in order to find out their origin and timing. Petrographic observations on polish surfaces show that the coal clasts are either entirely xylitic/vitrinitic particles or coals including a broader range of macerals. The detected minerals in the samples are mostly derived from the parental coal seams and, to a lesser extent, precipitated from penetrated pore-water in the cleats/fractures of clasts. The %Rr values of coal clasts in Carboniferous sediments are generally relatively higher than those measured in the coal seams due to weak oxidation during transportation. Furthermore, similar mineralogical and maceral compositions between coal clasts and coal seams imply that these clasts were mainly eroded during the peatification and/or early coalification of parental seams and display similar coalification patterns. The close %Rr value of a coal clast sample in the Early Aptian Zonguldak Formation and Carboniferous coal seams could suggest that this coal clast sample is presumably derived from the coal seams eroded during Early Aptian

Determination of Elemental Affinities in Soma Lower (kM2) Coal Seam in Soma Basin Using Agglomerative Hierarchical Clustering Algorithm

Coal, as most common fossil-fuel, has been subjected to several geochemical and mineralogical studies due to presence of potentially toxic elements. In these studies, statistical methods (e.g., correlation coefficient, cluster and factor analyses) are mainly used for determination of toxic elements affinities in coal. In environmental concerns, the statistical methods are recently topic of discussion due to correlations between some elements with minerals that cannot be chemically affiliated. Nevertheless, microanalyses methods as like scanning electron microscopy-energy dispersive spectrometer (SEM-EDX) or electron microprobe (EPMA) and machine learning algorithms more commonly applied in determination of affinities of some toxic elements in coal. This study aims to correlate geochemical and mineralogical data of lower (kM2) coal seam in the Soma coalfield with Bray-Curtis, Cosine and Tanimoto similarities and different similarity measures like Pearson correlation co-efficiencies. The results of similarity measures evaluated using agglomerative hierarchical clustering algorithm (average linkage) and elements grouped in several clusters. Most of identified elemental groups, expected a few of them, based on Canberra, Chebyshev, Bray-Curtis and Tanimoto measures do not appear to be in agreement with mineralogical and geochemical data. Nevertheless, elements affiliated with aluminosilicate elements (e.g., Al, K, B, and Cs) are grouped in together, and elements (e.g., S, As, Mo and U) related with redox conditions in coal formation environment are located in the same group according to Pearson correlation co-efficiencies and cosine similarity. In addition, this data is in agreement with SEM-EDX and XRD data of studied coal samples. These results imply that cosine similarity could be an alternative for Pearson correlation coefficiency’s method in coal studies. As a result, more detailed studies using both similarity measures should be conducted in future, and these similarity measures should always be correlated with SEM-EDX and XRD data.</p

Mineralogy, petrography, and Rock-Eval pyrolysis of late Oligocene coal seams in the Malkara coal field from the Thrace Basin (NW Turkey)

The Thrace Basin hosts the second-largest natural gas and oil resource of Turkey. Several mineable late Oligocene coal seams are located close to natural gas fields in the basin. This study focuses on the assessment of late Oligocene seams in the Malkara coal field using mineralogical, petrographic, and Rock-Eval pyrolysis data. The variations in coal properties seem to be mainly controlled by common peat-forming vegetation and detrital input ratio into palaeomires. The studied samples are characterized by variable TOC, Tmax and HI values and high H contents. Even though the relatively high H contents seem to be related to high total liptinite contents, the presence of hydrogen-rich telohuminite macerals, particularly ulminite A, may be the main reason for elevated H contents in the studied samples. Furthermore, the Rock-Eval analyses results, which imply the presence of mixed type III-IV kerogens, conflict with coal petrography data. The differences could be a by-product of carbonate minerals breakdown during pyrolysis; however; the presence of hydrogen-rich telohuminite macerals, which could have originated from resinous woody peat-forming plants, could cause suppression S2 peak and elevation of S3 peak due to release additional COx from the breakdown of hydrogen- and oxygen-rich compounds in telohuminite macerals during pyrolysis. Therefore, HI, Tmax, and OI values are not matched with maceral compositions. Moreover, the relatively higher Tmax and %Rr values of studied late Oligocene coal seams in the Malkara coal field than early Oligocene shales and late Oligocene coals in the NE parts of the basin could be related to higher thermal gradient and/or post-Oligocene tectonic movements. Overall, the results imply that the coals are mostly gas-prone; thus, the studied coal seams along with unexploited coal seams near to the study area have a hydrocarbon generation potential for especially natural gas in the Danis , men Formation. The results of this study also show that the Rock-Eval pyrolysis data of low-rank humic coals similar to Malkara coals should be used with caution and cross-checked with results of traditional coal parameters such as ash yields, H contents, maceral, and mineralogical compositions to avoid misinterpretations

Evaluation of elemental affinities in coal using agglomerative hierarchical clustering algorithm: A case study in a thick and mineable coal seam (kM2) from Soma Basin (W. Turkey)

The hierarchical clustering algorithm, especially Pearson correlation coefficient, along with other statistical approach, is used statistical approach for determining the toxic elements affinities in coal, and this method is one of the common approaches due to the correlations between some elements with minerals that cannot be chemically affiliated. This study aims to correlate geochemical and mineralogical and data of the lower seam (up to 30 m) in the Soma coalfield with Cosine and Bray-Curtis similarity measures, Chebyshev and Canberra distance metrics, and also Pearson correlation and Tanimoto coefficients. The results have been evaluated using agglomerative hierarchical clustering algorithm with average linkage, and elements are grouped in several clusters. Some of the similarity measures and distance metrics do not seem to agree with mineralogical and geochemical data. However, elements affiliated with aluminosilicate elements (e.g., Al, K, and Cs) are grouped, and elements (e.g., As, Mo and U) related to redox conditions in coal depositional environment are located in the same group according to Pearson correlation coefficient and Cosine similarity. In addition, this data has been observed in agreement with SEM-EDX and XRD data of studied coal samples. The present study indicates that Cosine similarity could be an alternative for the Pearson correlation coefficient in coal studies.</p

quality from the Oltu-Balkaya Basin, northeastern Turkey

This study addresses the depositional environments of the Oligo/Miocene coal-bearing Susuz Formation and Komurlu Formation from the Oltu-Balkaya Basin, northeastern Turkey, and coal quality of the Ince and Susuz seams from the Susuz Formation, which was formed in a mainly meandering fluvial environment. The Komurlu Formation that conformably overlies the Susuz Formation was developed in a mainly lacustrine environment. Six channel samples from the Ince seam and 13 channel samples from the Susuz seam exploited in the underground mines around Balkaya were collected and evaluated in this study. The samples show that the Ince and Susuz seams, on an air-dried basis, respectively, average high ash yields (38.9 and 31.2%), high total sulfur contents (3.49 and 2.89%), and relatively high calorific values (3956 and 4775 kcal/kg). The mean random ulminite reflectance (0.54 and 0.56% Rr) and nonagglomerating character imply that these coals are in a subbituminous-A coal rank. The mineral matter of the studied samples is made up of smectite, quartz, pyrite, calcite, feldspar, and traces of illite and gypsum. Petrographic studies show that some of pyrite and all calcites were detected in cleat and fracture infillings

GEÇ OLİGOSEN-ERKEN MİYOSEN YAŞLI DANİŞMEN FORMASYONU İÇİNDEKİ KÖMÜRLERİN MİNERALOJİSİ, TOC VE ROCK-EVAL PİROLİZ DEĞERLERİ (MALKARA, TEKİRDAĞ, TÜRKİYE)

&Uuml;lkemizde &ouml;nemli doğalgaz &uuml;retim sahalarının bulunduğu Trakya Havzası&rsquo;nda geniş yayılım sunan Ge&ccedil; Oligosen-Erken Miyosen yaşlı Danişmen Formasyonunda &ccedil;eşitli kalınlıklarda k&ouml;m&uuml;r damarları bulunmaktadır. Havza dolgusunu oluşturan sedimanter istifin &ccedil;&ouml;kelim ortamı, kaynak kaya potansiyeli ve rezervuar kaya &ouml;zellikleriyle ilgili bazı &ccedil;alışmalar bulunmakla beraber, &ouml;zellikle Danişmen Formasyonunda bulunan k&ouml;m&uuml;rlerin mineralojisi, TOC ve piroliz değerleriyle ile ilgili &ccedil;alışmalar sınırlıdır. Literat&uuml;r bilgilerine g&ouml;re Danişmen Formasyonu i&ccedil;indeki k&ouml;m&uuml;r damarlarının &ccedil;&ouml;kelim ortamı, delta d&uuml;zl&uuml;ğ&uuml; ve denizel etkiye a&ccedil;ık bataklık alanlarıdır. Buna g&ouml;re, ilksel turbalıkların &ccedil;&ouml;kelim ortamındaki değişimlere bağlı olarak maseral ve mineral i&ccedil;eriğinde, TOC ve piroliz değerlerinde farklılıkların olabileceği beklenmiştir. Bu ama&ccedil;la bir proje &ccedil;alışması y&uuml;r&uuml;t&uuml;lm&uuml;ş ve ilk sonu&ccedil;lar bu bildiri kapsamında tartışılmıştır. Trakya Havzası&rsquo;nın g&uuml;neybatısındaki Malkara&rsquo;nın kuzeybatısında işletilmekte olan k&ouml;m&uuml;r sahalarından 3 adet &ouml;l&ccedil;&uuml;l&uuml; stratigrafik kesitten toplam 50 k&ouml;m&uuml;r &ouml;rneği alınmıştır. K&ouml;m&uuml;r &ouml;rneklerinde matriks, mineralce zengin ve ksilit&ccedil;e (odunsu) zengin litotipler tanımlanmıştır. &Ccedil;alışılan &ouml;rnekleri k&uuml;l (%3,2-61,2 havada kuru bazda), u&ccedil;ucu madde (%, 18,7-44,9 havada kuru bazda) ve toplam s&uuml;lf&uuml;r (%0,3-5,9, havada kuru bazda) değerleri geniş bir aralık sunmaktadır. K&ouml;m&uuml;r &ouml;rneklerinde X-ışını toz difraksiyonuyla tanımlanan mineraller; kil mineralleri (klorit, ilit/mika), kuvars, karbonat mineralleri (kalsit ve siderit), pirit, feldspat ve jipstir. Rock-Eval piroliz ve TOC analiz sonu&ccedil;larına g&ouml;re k&ouml;m&uuml;r &ouml;rneklerinin TOC miktarı %15,71-51,50, Tmax değerleri 389-436 &deg;C, Hidrojen İndeksleri (HI) 39-161 mg HC/g kaya ve Oksijen İndeksleri (OI) 71-123 mg CO2/g kaya arasında değişmektedir. Bu değerler Trakya Havzası&rsquo;ndaki Oligosen k&ouml;m&uuml;rlerinden elde edilen Rock-Eval Piroliz ve TOC verilerine benzerlik sunmaktadırlar. Bununla beraber TOC değerlerindeki geniş yayılım &ouml;rneklerin k&uuml;l i&ccedil;erikleri g&ouml;z &ouml;n&uuml;ne alındığında beklenebilir durumdur. &Ouml;rneklerden elde edilen y&uuml;ksek OI değerlerine k&ouml;m&uuml;r &ouml;rneklerde inertinit maserallerin ve karbonat minerallerin varlığından kaynaklanabileceği d&uuml;ş&uuml;n&uuml;lebilir. K&ouml;m&uuml;r &ouml;rneklerinin HI, OI ve Tmax değerlerine g&ouml;re &ouml;rneklerde tip III kerojen genellikle yaygındır. Bazı &ouml;rneklerde ise karışık Tip II-III ve Tip III-IV kerojenleri yaygındır. İncelenen &ouml;rnekler &ccedil;oğunlukla olgunlaşmamış-erken olgunlaşmıştır ve ayrıca, sınırlı sayıda &ouml;rnek ise olgunlaşmıştır. Bu veriler ışığında incelenen k&ouml;m&uuml;r damarların ağırlıklı olarak gaz t&uuml;retme eğilimine sahip oldukları g&ouml;r&uuml;lmektedir. K&ouml;m&uuml;r fasiyes diyagramları bitki &ouml;rt&uuml;s&uuml;n&uuml;n ve turba &ccedil;&ouml;kelim ortamının damarlar arasında farklılıklar sunduklarını g&ouml;stermektedir. Bu &ccedil;alışma Hacettepe &Uuml;niversitesi BAP Koordinasyon Birimi tarafından FHD-2017-14241 nolu proje kapsamında desteklenmektedir. Anahtar Kelimeler: Trakya Havzası, Danişmen Formasyonu, &ccedil;&ouml;kelm