Rıza OSKAY

This study focuses on meso- and microporosity of the subbituminous kM2 coal seam and its relation to coal characteristics. The coal seam is being mined in an underground coal mine at the Eynez sector in the Soma Basin (Western Turkey). The analysed coal samples are characterized by low moisture (avg. 8.2%, on air-dry basis) and total S content (avg. 1.5%, on dry basis), and moderate ash yield (avg. 26.1%, on dry basis). The predominant maceral group is huminite, in which telohuminite is the dominant maceral subgroup (up to 57.1 vol.%, on whole-coal basis), whereas liptinite and inertinite maceral groups occur in low but variable proportions. Mineralogically, the samples are composed of quartz, clay minerals (kaolinite and illite), carbonates, pyrite, and rarely feldspars and gypsum. Statistical and SEM-EDX analyses indicate that the majority of elements have inorganic affinity, particularly the aluminosilicate minerals. The specific surface area and volume of mesopores, and average mesopore size determined by low pressure N2 adsorption, range widely throughout the studied seam section. Micropore characteristics, analysed by low-pressure CO2 adsorption, demonstrate that micropores are abundant, and specific surface area and volume of micropores vary widely. Surface area and volume of mesopores are slightly higher in the lower part of the seam, whereas the opposite was observed for surface area and volume of microspores. These trends may imply that hydrostatic pressure has little impact upon mesopore characteristics, although increased ash yields in the lower part of the seam suggest that minerals are the major contributor of coal mesopores. Furthermore, total C contents and huminite macerals, particularly telohuminite, display positive correlations with micropore characteristics. Thus, the variations in the microporosity are mainly correlated with the proportion of organic matter (macerals) in the analysed samples. The contents of aluminosilicate-affiliated elements display moderate to strong positive correlations with surface area and volume of mesopores, and total S and B contents display weak positive correlations with surface area and volume of micropores. The element B likely precipitated from porewater or intra-seam solutions during coalification and was absorbed by macerals having abundant microporosity. The abundance of micropores along with frequent disseminated pyrite crystals within the reactive macerals (telohuminite group) and higher total S contents in the upper parts of the seam could increase the risk of self-heating. Therefore, care should be taken to use caution when mining the upper part of the seam.

The Neogene Soma Basin, western Turkey, hosts three coal seams (kM2, kM3 and kP1) and several altered tuff layers within the Miocene sequences. This study focuses on the evaluation of coal-petrography, mineralogical and elemental compositions, as well as the Rock-Eval pyrolysis of the three coal seams from Eynez, Işıklar and Deniş sectors, and to identify the mineralogy of altered tuff layers within kM2 and kP1 seams. The routine coal quality analyses show that coal samples from the kM2 seam are characterized by lower ash yields and total S contents, and higher gross calorific values than kM3 and kP1 seams. The mineralogical composition of the bulk coal samples varies between all three seams. The statistical treatment implies that major elements in bulk coal samples such as Al, Fe, K, Mg and Na, and the vast majority of minor and trace elements have inorganic affinity. The trace element contents and elemental enrichments in the coal samples are generally changeable from seam to seam, which could be related to differences in ash yield and mineralogy. Altered tuff layers, or tonsteins were identified in kM2 and kP1 seams. The tonsteins are clay rich, and certain trace elements (e.g. As and Zr) are enriched in the coal layers beneath the tuff layers in the kM2 seam. This might be related to penetration of leached pore water into these layers and precipitation of epigenetic minerals.

The coal-petrography composition and the coal-facies diagrams show that the precursor peat of the kM2 seam was accumulating under telmatic, mesotrophic, anoxic conditions, whereas the water level was high and stable. The relatively low ash yields and thicker coal beds suggest a lower clastic input from the basin margins, and water table fluctuations resulted in calcareous intercalations in the kM3 and kP1 seams. These imply the development of limno-telmatic conditions whereas fluvial activity affected during peat accumulation of both seams. Considering the maceral composition along with the coal thickness, coal seams in the Soma Basin might display oil-generation potential; however, the pyrolysis analysis shows that the studied coal seams are mainly gas-prone and only certain coal beds have mixed-hydrocarbon generation capacity. All data presented in this study indicates that lithological features, differences in coal qualities and elemental contents in the Soma Basin were mainly controlled by changes in the depositional conditions and the detrital input during Miocene.

Regional tectonic movements during the Neogene period resulted in the development of several fault-controlled basins in Central Anatolia; many of these basins host economic coal deposits. The recently discovered Karapınar-Ayrancı coal deposit is the most important one due to its large reserves (c. 1.8 Gt) and location in the vicinity of important urban areas. The paper aims to reconstruct the palaeoenvironmental conditions before, during and after coal formation in the eastern part of Karapınar-Ayrancı deposit by means of coal-petrography and mineralogical data combined with sedimentological and palaeontological data. The basinal infilling consists of mainly lacustrine, fluvial and alluvial sediments. The coal seams comprise several beds intercalating with claystone, mudstone and marl. The coal being lignite in rank, displays high ash yield (36.4 wt.%, on dry basis) and high total sulphur content (avg. 7.7 wt.%, on dry, ash-free basis). Facies diagrams and lithological features of the coal seams suggest that peat was accumulating under pure telmatic to limnotelmatic conditions; however, peat accumulation ceased several times due to a rise in water level. Therefore, clastic (e.g. quartz, clay minerals) and authigenic (e.g. pyrite) mineral contents are variable along the seam profile. Gastropod and ostracod fauna points to freshwater conditions in the palaeomire. High total sulphur and evaporite mineral (e.g. halite) contents usually point to brackish-saline conditions during peat accumulation; however, in case of the Karapınar-Ayrancı deposit, high sulphur contents can be related to sulphate-rich karstic aquifer, which contributed to the palaeomire water supply.

This study focuses on the Pleistocene Gölbaşı-Harmanlı coal deposit located in the East Anatolian Fault Zone (EAFZ), SE Turkey. The principal aim of the study is to determine factors that controlled peat accumulation by means of palaeontological data, routine coal analyses (proximate-ultimate), mineralogical composition based on XRD and SEM-EDX, and coal petrography. The basin-infillings consist of alluvial, fluvial, and lacustrine sediments. Palaeolake levels along with sedimentation were presumably controlled by the EAFZ during Late Pliocene to Holocene times. The investigated coal-bearing zone is composed of a thick coal seam (up to 39 m) with thin clastic intercalations of fossiliferous claystones. Palaeontological data from these clastic bands imply that the coal accumulated during Middle Pleistocene times, an uncommon period for the formation of thick coals in Turkey.

We suggest that the movements of the EAFZ caused rapid subsidence, and along with favourable climatic conditions, allowed large peat accumulation in a relatively short period of time. The results of proximate and ultimate analyses from 29 coal samples obtained from two cores show high ash yields (av. 32%), relatively low sulphur content (av. 1.8%), low net calorific value (av. 11.6 MJ/kg) and low total carbon content (av. 35.5%) on an air-dry basis. The mean random reflectances of eu-ulminite B indicate a low-rank coal. Maceral compositions and maceral indices indicate that the peat accumulated under limno-telmatic, mesotrophic conditions, with peat-forming vegetation being composed of mainly herbaceous plants.

Ostracoda and Mollusca fauna from intercalating clastic layers within the coal seam provide important information about the geographic distribution of fossil taxa, environmental evaluation of the intercalations, and the age of the studied coal seam. The Ostracoda species Gomphocythere geareyi was identified within the coal seam for the first time. Humphcypris subterranea is the first fossil record of this Ostracoda genus in Turkey. These, along with the presence of the Gastropoda subspecies Bithynia phialensis syriaca, imply a transport into the palaeomire via migratory birds from the Eastern Mediterranean areas. Discovery of Humphcypris subterranea, Bithynia phialensis syriaca, and the African originated genus Gomphocythere in the Gölbaşı-Harmanlı coal deposit marks their northernmost worldwide occurrence.

The study focuses on the firstly documented Çardak coal seam cored in the Neogene Acıgöl Basin (Denizli Province) being formed in a late stage of Alpine orogeny in SW Turkey. The aim is to contribute reconstructing the palaeoenvironmental conditions before, during and after coal formation, on the basis of coal-petrology, mineralogical and palaeontological data combined with the results of previous studies. The basin infilling consists of alluvial, fluvial and lacustrine sediments; their deposition depended on the water level in the basin, which in turn, was controlled by the interplay between tectonics and climate. Coal seam was probably formed in Latest Miocene/Early Pliocene under the influence of basin's fluvial regime in oxbow and terminal lakes. The coal seam comprises alternating inorganic and coal layers logged between depths of 599.00 to 627.00 m beneath surface. The coal being lignite to subbituminous in rank, displays moderate to high ash yield (21.31–46.11 wt.%, on dry basis) and high total sulphur content (up to 13.30 wt.%, on dry, ash-free basis). The maceral composition points to an origin from mainly herbaceous helophytes along with woody species. In the upper part of the core the presence of salinity-tolerant ostracod species along with gypsum and halite are documented. The palaeontological and mineralogical data obtained imply changes of climate, water level and lake chemistry in the basin.

The Gölbaşı-Harmanlı coal seam is located within the pull-apart Gölbaşı Basin (Adıyaman, SE Anatolia) controlled by the NE-SW trending East Anatolian Fault Zone (EAFZ). This study focuses on micropaleontological analyses of twenty-one samples that were obtained from the Gölbaşı ope npit coal mine (GOCM) section. Six ostracod taxa ( Cypridopsis vidua, Herpetocypris cf. chevreuxi, Humphcypris subterranea, Psychrodromus olivaceous, Candona sp. and Gomphocythere cf. geareyi), seven gastropod taxa (Theodoxus anatolicus , Bithynia phialensis cf. syriaca, Horatia parvula, Bythinella sp., Valvata (Cincinna) piscinalis, Galba truncatula, Gyraulus piscinarum acutissiumus ) and as well as one bivalve (Pisidium personatum) taxa were identified from the GOCM (this study). Furthermo re, charophyte gyrogonites and fish teeth remains were obtained. Considering the ostracod assemblage determined from the GOCM, and the micromammal data from intercalations of the Gölbaşı coal seam (Suata -Alparslan and Dinçarslan, 2011), the Gölbaşı coal seam deposited during the Middle Pleistocene. The identified microfaunal assemblage suggests that different biogeographic realm were hosted in the GOCM during the Middle Pleistocene, such as Cosmopolitan (C. vidua), widely distributed (H. chevreuxi), Holarctic (G. truncatula), Palearctic (P. olivaceous, V. piscinalis and P. personatum), Eastern Mediterranean (H. subterranea, G. geareyi and B. phialensis syriaca) and endemic (G. piscinarum acutissiumus, H. parvula and T. anatolicus) species. Nevertheless, several of these taxa were commonly reported from Neogene and Quaternary basins in Turkey, the most significants are G. cf. geareyi, H. subterranea and B. phialensis cf. syriaca in the GOCM where their northernmost limits were identified. The presences of these taxa also suggest the possible transportation of them from the other Eastern Mediterranean areas (e.g. Orontes (Syria) and Jordan Valley (Israel)) during the Quaternary.

During Neogene major tectonic movements around the eastern Mediterranean Sea caused the uplift of Anatolian Peninsula that resulted in the formation of several sedimentary basins. The Yalvaç Basin is one of these formed during this period of time and located on the eastern flank of the Isparta Angle. The pre-Neogene basement and marginal rocks compose of Ordovician-Permian metamorphic rocks, Triassic-Cretaceous carbonates and Cretaceous ophiolites. The Neogene basin infilling consists of fluvial and lacustrine sediments, which divided into four formations (Bağyaka, Yarıkkaya, Göksöğüt and Kırkbaş), and several mineable coal seams host within these sequences. Coal and inorganic samples were picked up from the SK-1 drill core at the southern part of the basin (SE of Şarkikaraağaç). Macroscopically coal samples are black and grey in colour and in site bear fossil shell remains. Matrix and mineral-rich lithotypes were identified. The studied samples display high ash yields (24.7-54.0%, on dry basis), volatile matter (58.5-71.4%, on dry, ash-free basis) and total sulphur (6.2-10.6%, on dry, ash-free basis) contents. Huminite is dominant maceral group, whereas liptinite and inertinite in low proportion. The minerals identified in bulk coal samples are clay minerals (illite, kaolinite, chlorite and montmorillonite), carbonates (calcite, aragonite), quartz and less frequently pyrite and gypsum. Ostracod, gastropod, charophyte and fish teeth remains were determined and ostracods were identified from inorganic sediments within the coal-bearing strata. The ostracod fauna, particularly, show similarities with other ostracod faunas in the Central and Western Anatolia and the fauna indicates freshwater-oligohaline lacustrine conditions. The coal facies diagrams along with geochemical data indicate that peat accumulated under anoxic limno-telmatic to telmatic conditions. The maceral composition revealed the peat-forming vegetation an origin from mainly woody species (e.g. shrubs) along with herbaceous helophytes. The existence of freshwater conditions suggest high sulphur contents of coal samples related to carbonate- and sulphate-rich water support into palaeomire. Such support could cause neutral to alkaline conditions where carbonate minerals could form together with syngenetic pyrites. Furthermore, ostracod data indicates that the coal-bearing sequences were commenced to deposit in the Late Miocene. On the basis of the age and lithological correlations, the studied coal-bearing strata seems to be equivalent of the Göksöğüt Formation in the Yalvaç Basin.