MINERALOGY AND GEOCHEMISTRY OF COAL-BEARING TUNÇBİLEK FORMATION İN THE TUNÇBİLEK-TAVŞANLI COALFIELD (KÜTAHYA, W-TURKEY)

Year 2023, Issue: 052, 65 - 98, 29.03.2023

Selin Karadirek

https://doi.org/10.59313/jsr-a.1192487

Cited By: 1

Abstract

Tunçbilek-Tavşanlı (Kütahya) Basin is among the most important Neogene coal deposits of Turkey. This study aims to determine the mineralogical and geochemical properties of the rocks (coal, roof, floor and parting) in the Tunçbilek-Tavşanlı coal field. The main abundant minerals in Tunçbilek-Tavşanlı coals are quartz, kaolinite, illite-smectite and siderite. Dolomite, illite, smectite, mica, feldspar, pyrite, chlorite and jarosite are less abundant minerals. The mineralogy of non-coal rocks is similar to that of coals, but pyrite is absent. The most abundant major oxides in the studied samples are SiO2, Al2O3 and Fe2O3, respectively. The SiO2, Al2O3 and MgO are the most abundant major oxides, respectively, in the claystone samples representing partings. Trace element concentrations of Tunçbilek-Tavşanlı coal samples mostly showed higher concentrations (excluding Ba, Sr, Pr, Tb, Dy, Ho, Tm, As, Cd and Bi) compared to the world low-rank coal average. According to the relative enrichment of the elements, the concentration coefficients (CC) of the coal samples are generally in the range of slightly enriched-normal; The CC of the non-coal samples mainly indicate the normal. The average REY concentration in the studied samples is higher than the world low-rank coal concentration and mostly showed L-type enrichment. Moreover, the REY concentration of the supercritical groups constitutes a significant part of the REYtotal concentration in the samples taken from the coal horizon. However, the studied samples are in the unpromising area according to the low cut-off grade value and the relationship between cut-off grade-Coutl. The high correlation coefficient between ash content and REY concentrations also indicates a mineral substance relationship. Al2O3/TiO2 (between 12.5-31.7) ratios of Tunçbilek-Tavşanlı samples show intermediate and felsic source rocks.

Keywords

Coal, REE+Y (REY), Trace elements, Tunçbilek

Supporting Institution

Akdeniz Üniversitesi Bilimsel Araştırma Projeleri Koordinasyon Birimi

Project Number

FYL-2019-5015

Thanks

This study was funded by Akdeniz University Research Coordination Unit (FYL-2019-5015). The author would like to thank Turkish Coal Enterprises for their support during field work and sampling, and all the reviewers for their valuable comments and contributions.

References

• [1] Thurber, M.C., Morse, R.K., (2015), The Global Coal Market: Supplying Major Fuel for Emerging Economies, Cambridge University Press, Cambridge, 702 p.
• [2] Dai, S., Bechtel, A., Eble, C.F., Flores, R.M., French, D., Graham, I.T., Hood, M.M., Hower, J.C., Korasidis, V.A., Moore, T.A., Puttmann, W., Wei, Q., Zhao, L., O'Keefem, J.M.K., (2020), Recognition of peat depositional environments in coal: A review, International Journal of Coal Geology, 219, 103383.
• [3] Dai, S., Tian, L., Chou, C.L., Zhou, Y., Zhang, M., Zhao, L., Wang, J., Yang, Z., Cao, H., Ren, D., (2008a), Mineralogical and compositional characteristics of Late Permian coals from an area of high lung cancer rate in Xuan Wei, Yunnan, China: occurrence and origin of quartz and chamosite, International Journal of Coal Geology, 76, 318–327.
• [4] Dai, S., Ren, D., Zhou, Y., Chou, C.L., Wang, X., Zhao, L., Zhu, X., (2008b), Mineralogy and geochemistry of a superhigh-organic-sulfur coal, Yanshan Coalfield, Yunnan, China: evidence for a volcanic ash component and influence by submarine exhalation, Chemical Geology, 255, 182–194.
• [5] Dai, S., Wang, X., Chen, W., Li, D., Chou, C.L., Zhou, Y., Zhu, C., Li, H., Zhu, X., Xing, Y., Zhang, W., Zou, J., (2010), A high-pyrite semianthracite of Late Permian age in the Songzao Coalfield, southwestern China: mineralogical and geochemical relations with underlying mafic tuffs, International Journal of Coal Geology, 83, 430–445.
• [6] Dai, S., Ren, D., Chou, C.L., Finkelman, R.B., Seredin, V.V., Zhou, Y., (2012), Geochemistry of trace elements in Chinese coals: a review of abundances, genetic types, impacts on human health, and industrial utilization, International Journal of Coal Geology, 94, 3-21.
• [7] Finkelman, R.B., Dai, S., French, D., (2019), The importance of minerals in coal as the hosts of chemical elements, International Journal of Coal Geology, 212, 103251.
• [8] Dai, S., Finkelman, R.B., (2018), Coal as a promising source of critical elements: progress and future prospects, International Journal of Coal Geology, 186, 155–164.
• [9] Güllüdağ, C.B., Aksoy, E., Ünal, N., Özmen, S.F., (2020), Radioactivity concentrations and risk assessment of Tekirdağ lignites (case study of Malkara coalfield), Acta Geophysica, 68, 1411–1420.
• [10] Seredin, V.V., Finkelman, R.B., (2008), Metalliferous coals: A review of the main genetic and geochemical types, International Journal of Coal Geology, 76, 253–289.
• [11] Lin, R., Soong, Y., Granite, E.J., (2018b), Evaluation of trace elements in U.S. coals using the USGS COALQUAL database version 3.0. Part II: Non-REY critical elements, International Journal of Coal Geology, 192, 39–50.
• [12] Zhao, L., Ward, C.R., French, D., Graham, I.T., Dai, S., Yang, C., Xie, P., Zhang, S., (2018), Origin of a kaolinite-NH4-illite-pyrophyllite-chlorite assemblage in a marine-influenced anthracite and associated strata from the Jincheng Coalfield, Qinshui Basin, Northern China, International Journal of Coal Geology, 185, 61–78.
• [13] Seredin, V.V., Dai, S., (2012), Coal deposits as potential alternative sources for lanthanides and yttrium, International Journal of Coal Geology, 94, 67–93.
• [14] Hower, J.C., Eble, C.F., Dai, S.F., Belkin, H.E., (2016), Distribution of rare earth elements in eastern Kentucky coals: indicators of multiple modes of enrichment?, International Journal of Coal Geology, 160, 73–81.
• [15] Kolker, A., Scott, C., Hower, J.C., Vazquez, J.A., Lopano, C.L., Dai, S., (2017), Distribution of rare earth elements in coal combustion fly ash, determined by SHRIMP-RG ion microprobe, International Journal of Coal Geology, 184, 1–10.
• [16] Laudal, D.A., Benson, S.A., Addleman, R.S., Palo, D., (2018), Leaching behavior of rare earth elements in Fort Union lignite coals of North America, International Journal of Coal Geology, 191, 112–124.
• [17] Lin, R., Soong, Y., Granite, E.J., (2018a), Evaluation of trace elements in U.S. coals using the USGS COALQUAL database version 3.0. Part I: rare earth elements and yttrium (REY), International Journal of Coal Geology, 192, 1–13.
• [18] Wagner, N.J., Matiane, A., (2018), Rare earth elements in select Main Karoo Basin (South Africa) coal and coal ash samples, International Journal of Coal Geology, 196, 82–92.
• [19] Seredin, V.V., (2012), From coal science to metal production and environmental protection: a new story of success, International Journal of Coal Geology, 90, 1–3.
• [20] Dai, S., Yan, X., Ward, C.R., Hower, J.C., Zhao, L., Wang, X., Zhao, L., Ren, D., Finkelman, R.B., (2018), Valuable elements in Chinese coals: a review, International Geology Review, 60, 590–620.
• [21] Arni, P., (1942), Anadolu ofiyolitlerinin yaşlarına mütedir malumat, Bulletin of the Mineral Research and Exploration, 28, 472-488.
• [22] Nebert, K., (1960), Tavşanlı'nın batı ve kuzeyindeki linyit ihtiva eden Neojen sahasının mukayeseli stratigrafisi ve tektoniği, Bulletin of the Mineral Research and Exploration, 54, 7-35.
• [23] Kalafatçıoğlu, A., (1962), A note on the geology of the region between Tavşanlı and Dağardı, and on the age of the serpentines and limestones, Bulletin of the Mineral Research and Exploration, 58, 38-46.
• [24] Okay, A.I., (1981), The geology and blueschist metamorphism of the ophiolites in Northwest Turkey (Tavşanlı-Kütahya), Bulletin of the Geological Society of Turkey, 24, 85-95.
• [25] Okay, A.I., (1984), Kuzeybatı Anadolu’da yer alan metamorfik kuşaklar, Ketin Sempozyumu, pp. 83-92.
• [26] Baş, H., (1986), Tertiary geology of the Domaniç-Tavşanlı-Kütahya-Gediz region, Geological Engineering, 11-18.
• [27] Helvacı, C., İnci, U., Yağmurlu, F., Yılmaz, H., (1987), Neogen stratigraphic and economic potential of Western Turkey, Journal of Isparta Engineering Faculty of Akdeniz University, 3, 31-45.
• [28] Kocyigit, A., Bozkurt, E., (1997), Kütahya-Tavşanlı çöküntü alanının neotektonik özellikleri, TÜBİTAK Project No: YDABÇAG-126, 78 p.
• [29] Günal Türkmenoğlu, A., Yavuz-Işık, N., (2007), Mineralogy, chemistry and potential utilization of clays from coal deposits in the Kütahya province, Western Turkey, Applied Clay Science, 42, 63-73.
• [30] Özburan, M., (2009), Neotectonic investigation of Kütahya and Its surrounding, Dissertation, Kocaeli University, 209 p.
• [31] Göncüoğlu, M.C., (2011), Geology of the Kütahya-Bolkardağ belt, Bulletin of the Mineral Research and Exploration, 142, 223-277.
• [32] Erkoyun, H., Kadir, S., Huggett, J., (2019), Occurrence and genesis of tonsteins in the Miocene lignite, Tunçbilek Basin, Kütahya, western Turkey, International Journal of Coal Geology, 202, 46-68.
• [33] Soytürk, T., (1992), Tunçbilek kömürlerinin kendiliğinden yanmaya yatkınlıklarının araştırılması, Dissertation, Anadolu University, 76 p.
• [34] Yavuz, N., (1994). Palynology, petrography and chemistry of the Tavşanlı coals (Kütahya), Dissertation, Middle East Technical University, Ankara, , 90 p.
• [35] Bacak, G., (2003). Mineralogical, petrographical and petrogenetical study of Southern Dağardı (Tavşanlı-Kütahya) ophiolite, Dissertation, İstanbul Technical University, İstanbul, 284 p.
• [36] Karayigit, A.I., Celik, Y., (2003), Mineral matter and trace elements in Miocene coals of the Tuncbilek-Domanic Basin, Kutahya, Turkey, Energy Sources, 25, 339-355.
• [37] Parlak, A., (2010), Briquetting Tunçbilek lignites and retention of sulfur in ash during combustion, Dissertation, Gazi University, Ankara, 104 p.
• [38] Akkiraz, M.S., Akgün, F., Utescher, T., Wilde, V., Bruch, A.A., Mosbrugger, V., Üçbaş, S.D., (2012), Palaeoflora and climate of lignite-bearing lower−middle Miocene sediments in the Seyitömer and Tunçbilek sub-basins, Kütahya province, Northwest Turkey, Turkish Journal of Earth Sciences, 21, 213-235.
• [39] Helvacı, C., Ersoy, E.Y., Billor, M.Z., (2017), Stratigraphy and Ar/Ar geochronology of the Miocene lignite‑bearing Tunçbilek‑Domaniç Basin, western Anatolia, Inernational Journal of Earth Science, 106, 1797-1814.
• [40] Akçay, A., (2017), Neotectonic investigation of the coaly Neogene area between Kızılbük-Degirmisaz (Tavşanlı/Kütahya), Dissertation, Dumlupınar University, 67 p.
• [41] Emre, Ö., Duman, T.Y., Özalp, S., Şaroğlu, F., Olgun, Ş., Elmacı, H., Çan, T., (2018), Active fault database of Turkey, Bulletin of Earthquake Engineering, 16, 3229-3275.
• [42] Akgün, E., Özden, S., (2019), Plio-Quaternary stress states along the Kütahya Fault and surroundings, NW Turkey, Turkish Journal of Earth Sciences, 28, 671-686.
• [43] Kezer, Z., (2019), Tectonic geomorphology of the Kütahya Graben (Western Anatolia), Dissertation, Hacettepe University, 92 p.
• [44] Kazancı, C., (2019), Organic facies characteristics of FC pano opencast mine coals, Tunçbilek (Tavşanlı-Kütahya), Dissertation, Akdeniz University, Antalya, 67 p.
• [45] Cicioglu Sutcu, E., Şentürk, S., Kapıcı, K., Gökçe, N., (2021), Mineral and rare earth element distribution in the Tunçbilek coal seam, Kütahya, Turkey, International Journal of Coal Geology, 245, 103820.
• [46] Ketin, İ., (1966), Tectonic Units of Anatolia, Bulletin of the Mineral Research and Exploration, 66, 20-37.
• [47] Okay, A.I., Tüysüz, O., (1999), Tethyan sutures of northern Turkey, Geological Society Special Publication, 156 (1), 475−515.
• [48] Şengör, A.M.C., Yılmaz, Y., (1981), Tethyan evolution of Turkey: a plate tectonic approach, Tectonophysics, 75, 181-241.
• [49] Candan, O., Koralay, O.E., Akal, C., Kaya, O., Oberhänsli, R., Dora, O.Ö., Konak, N., Chen, F., (2011), Supra-Pan-African unconformity between core and cover series of the Menderes Massif/Turkey and its geological implications, Precambrian Research, 184, 1–23.
• [50] Candan, O., Çetinkaplan, M., Oberhänsli, R., Rimmelé, G., Akal, C., (2005), Alpine high-P/low-T metamorphism of the Afyon Zone and implications for the metamorphic evolution of Western Anatolia, Turkey, Lithos, 84, 102-124.
• [51] Göncüoğlu, M.C., Sayit, K., Tekin, U.K., (2010), Oceanization of the northern Neotethys: geochemical evidence from ophiolitic melange mélange basalts within the İzmir-Ankara suture belt, NW Turkey, Lithos, 116, 175–187.
• [52] Okay, A.I., Harris, N.B.W., Kelley, S.P. (1998), Exhumation of blueschists along a Tethyan suture in northwest Turkey, Tectonophysics, 285, 275–299.
• [53] Okay, A.I., Tansel, I., Tüysüz, O., (2001), Obduction, subduction and collision as reflected in the Upper Cretaceous–Lower Eocene sedimentary record of Western Turkey, Geological Magazine, 138 (2), 117–142.
• [54] Yılmaz, Y., Genç, S.¸C., Gürer, F., Bozcu, M., Yılmaz, K., Karacık, Z., Altunkaynak, S., Elmas, A., (2000), When did the Western Anatolian grabens begin to develop? In: Bozkurt, E., Winchester, J.A., Piper, J.A.D. (eds) Tectonics and magmatism in Turkey and the surrounding area, Journal of the Geological Society of London, 173, 131–162.
• [55] Ersoy, Y., Helvacı, C., (2007), Stratigraphy and geochemical features of the Early Miocene bimodal (ultrapotassic and calc-alkaline) volcanic activity within the NE-trending Selendi basin, western Anatolia, Turkey, Turkish Journal of Earth Sciences, 16, 117–139.
• [56] Ersoy, E.Y., Helvacı, C., Palmer, M.R., (2011), Stratigraphic, structural and geochemical features of the NE-SW trending Neogene volcanosedimentary basins in western Anatolia: implications for associations of supradetachment and transtensional strike-slip basin formation in extensional tectonic setting, Journal of Asian Earth Sciences, 41, 159–183.
• [57] Seyitoğlu, G., Anderson, D., Nowell, G., Scott, B.C., (1997), The evolution from Miocene potassic to Quaternary sodic magmatism in western Turkey: implications for enrichment processes in the lithospheric mantle, Journal of Volcanology and Geothermal Research, 76, 127–147.
• [58] Çelik, Y., (1999), Sedimentology and coal-potantial of the Domaniç (Kütahya) Neogene basin, Dissertation, İstanbul University, İstanbul, 205 p.
• [59] Özburan, M., Gürer, Ö.F., (2012), Late Cenozoic polyphase deformation and basin development, Kütahya region, western Turkey, International Geology Review, 54 (12), 1401-1418.
• [60] Yağmurlu, F., Inaner, H., Nakoman, E., Inci, U., (2004), Age, tectonic setting, and quality distribution of the Neogene lignite deposits of western Anatolia, Geologica Belgica, 7 (3), 251−258.
• [61] Ersoy, E.Y., Helvacı, C., (2016), Geochemistry and petrology of the lower Miocene bimodal volcanic units in the Tunçbilek–Domaniç basin, western Anatolia, International Geology Review, 58 (10), 1234-1252.
• [62] Vassilev, S.V., Vassileva, C.G., Baxter, D., Andersen, L.K., (2010), Relationships between chemical and mineral composition of coal and their potential applications as genetic indicators. Part 2. Mineral classes, groups and species, Geologica Balcanica, 39 (3), 43–67.
• [63] Vassilev, S., Vassileva, C., (1996), Mineralogy of combustion wastes from coal-fired power stations, Fuel Processing Technology, 47, 261–280.
• [64] Ward, C.R., (2016), Analysis, origin and significance of mineral matter in coal: an updated review, International Journal of Coal Geology, 165, 1–27.
• [65] Dai, S., Xie, P., Jia, S., Ward, C.R., Hower, H.C., Yan, X., French, D., (2017), Enrichment of U-Re-V-Cr-Se and rare earth elements in the Late Permian coals of the Moxinpo Coalfield, Chongqing, China: genetic implications from geochemical and mineralogical data, Ore Geology Review, 80, 1–17.
• [66] Baş, H., (1983), Domaniç-Tavşanlı-Kütahya-Gediz yörelerinin Tersiyer jeolojisi ve volkanitlerinin petrolojisi, MTA Report No. 7293, 86 p.
• [67] Türkmenoğlu, A.G., Yavuz-Işık, N., (2008), Mineralogy, chemistry and potential utilization of clays from coal deposits in the Kütahya province, Western Turkey, Applied Clay Science, 42, 63-73.
• [68] Fu, X., Wang, J., Tan, F., Feng, X., Zeng, S., (2013), Minerals and potentially hazardous trace elements in the late Triassic coals from the Qiangtang Basin, China, International Journal of Coal Geology, 116-117, 93–105.
• [69] Wang, X., Wang, X., Pan, S., Yang, Q., Hou, S., Jiao, Y., Zhang, W., (2018), Occurrence of analcime in the middle Jurassic coal from the Dongsheng Coalfield, northeastern Ordos Basin, China, International Journal of Coal Geology, 196, 126–138.
• [70] Finkelman, R.B., Palmer, C.A., Wang, P., (2018), Quantification of modes of occurrence of 42 elements in coal, International Journal of Coal Geology, 185, 138–160.
• [71] Hayashi, K.I., Fujisawa, H., Holland, H.D., Ohmoto, H., (1997), Geochemistry of ~1.9 Ga sedimentary rocks from northeastern Labrador, Canada, Geochimica Cosmochimica Acta, 61, 4115–4137.
• [72] He, B., Xu, Y.G., Zhong, Y.T., Guan, J.P., (2010), The Guadalupian–Lopingian boundary mudstones at Chaotian (SW China) are clastic rocks rather than acidic tuffs: implication for a temporal coincidence between the end-Guadalupian mass extinction and the Emeishan volcanism, Lithos, 119, 10–19.
• [73] Dai, S., Yang, J., Ward, C.R., Hower, J.C., Liu, H., Garrison, T.M., French, D., O'Keefe, J.M.K., (2015b), Geochemical and mineralogical evidence for a coal-hosted uranium deposit in the Yili Basin, Xinjiang, northwestern China, Ore Geology Review, 70, 1–30.
• [74] Dai, S., Seredin, V.V., Ward, C.R., Hower, J.C., Xing, Y., Zhang,W., Song,W.,Wang, P., (2015c), Enrichment of U–Se–Mo–Re–V in coals preserved within marine carbonate successions: geochemical and mineralogical data from the Late Permian Guiding Coalfield, Guizhou, China, Mineralium Deposita, 50, 159–186.
• [75] Ketris, M.P., Yudovich, Y.E., (2009), Estimations of Clarkes for carbonaceous biolithes: world average for trace element contents in black shales and coals, International Journal of Coal Geology, 78, 135–148.
• [76] Dai, S., Wang, P., Ward, C.R., Tang, Y., Song, X., Jiang, J., Hower, J.C., Li, T., Seredin, V.V., Wagner, N.J., Jiang, Y.,Wang, X., Liu, J., (2015a), Elemental and mineralogical anomalies in the coal-hosted Ge ore deposit of Lincang, Yunnan, southwestern China: key role of N2–CO2-mixed hydrothermal solutions, International Journal of Coal Geology, 152, 19–46.
• [77] Finkelman, R.B., (1981), Modes of occurrence of trace elements in coal: USGS Open-File Report No. OFR-81–99, 301 p.
• [78] Finkelman, R.B., (1988), The inorganic geochemistry of coal: a scanning electron microscopy view, Scanning Microscopy, 2 (1), 97-105.
• [79] Finkelman, R.B., (1994), Modes of occurrence of potentially hazardous elements in coal: levels of confidence, Fuel Processing Technology, 39, 21–34.
• [80] Rudnick, R.L., Gao, S. (2003), Treatise on geochemistry, volume 3, In: The Crust, Holland, H.D. and Turekian, K.K. (Eds), Elsevier-Pergamon, Oxford, 683 p.
• [81] Dai, S., Ji, D., Ward, C.R., French, D., Hower, J.C., Yan, X., Wei, Q., (2018b), Mississippian anthracites in Guangxi Province, southern China: Petrological, mineralogical, and rare earth element evidence for high-temperature solutions. International Journal of Coal Geology, 197, 84–114.
• [82] Jones, B., Manning, D.A.C., (1994), Comparison of geochemical indices used for the interpretation of palaeoredox conditions in ancient mudstones. Chemical Geology, 111, 111–129.
• [83] Karadirek, S., Altunsoy, M., (2022), Geochemical characteristics and paleodepositional setting of coal-bearing strata in Konya-Karapınar Basin, Central Anatolia, Turkey. Journal of African Earth Sciences, 186, 1-13.
• [84] Galarraga, F., Reategui, K., Martinez, A., Martinez, M., Llamas, J.F., Marquez, G., (2008), V/Ni ratio as a parameter in palaeoenvironmental characterisation of non-mature medium crude oils from several Latin American basins. Journal of Petroleum Science and Engineering, 61, 9–14.
• [85] El-Sabagh, S.M. Rashad, A.M. El-Naggar, A.Y. El Nady, M.M. Badr, I.A. Ebiad M.A., Abdullah E.S., (2018), API gravities, vanadium, nickel, sulfur, and their relation to gross composition: Implications for the origin and maturation of crude oils in Western Desert, Egypt, Petroleum Science and Technology, 36, 1-8.
• [86] Kimura, H., Watanabe, Y., (2001), Ocean anoxia at the Precambrian–Cambrian boundary. Geology, 29, 995–998.
• [87] Shi, L., Feng, Q.L., Shen, J., Ito, T., Chen, Z.Q., (2016), Proliferation of shallow-water radiolarians coinciding with enhanced oceanic productivity in reducing conditions during the Middle Permian, South China: evidence from the Gufeng Formation of western Hubei Province. Paleogeography, Paleoclimatology, Paleoecology, 444, 1–14.
• [88] Lerman, A., Imboden, D.M., Gat, J.R., (1995), Physics and Chemistry of Lakes. Springer, Berlin, Heidelberg.
• [89] Roy, D.K., Roser, B.P., (2013), Climatic control on the composition of Carboniferous–Permian Gondwana sediments, Khalaspir basin, Bangladesh. Gondwana Research, 23, 1163–1171.
• [90] Finkelman, R.B., (1993), Trace and minor elements in coal, In: Organic Geochemistry Engel, M.H., Macko, S.A. (Eds), Plenum, New York, pp. 593–607.
• [91] Dai, S., Zhou, Y., Ren, D., Wang, X., Li, D., Zhao, L., (2007), Geochemistry and mineralogy of the Late Permian coals from the Songzao Coalfield, Chongqing, southwestern China, Science In China Series D-Earth Sciences, 50, 678–688.
• [92] Yalçın Erik, N., (2022), A non-traditional resource for critical minerals; Rare Earths (REY+Sc) contents of some Turkish low rank coals, Kahramanmaras Sutcu Imam University Journal of Engineering Sciences, 25, 155-172.
• [93] Taylor, S.R., McLennan, S.H., (1985), The continental crust: Its composition and evolution, Blackwell, Oxford, 312 p.
• [94] Dai, S., Graham, I.T., Ward, C.R., (2016), A review of anomalous rare earth elements and yttrium in coal, International Journal of Coal Geology, 159, 82–95.
• [95] Yan, X., Dai, S., Graham, I.T., He, X., Shan, K., Liu, X., (2018), Determination of Eu concentrations in coal, fly ash and sedimentary rocks using a cation exchange resin and inductively coupled plasma mass spectrometry (ICP-MS), International Journal of Coal Geology, 191, 152–156.
• [96] Yan, X., Dai, S., Graham, I.T., French, D., (2019), Mineralogy and geochemistry of the Palaeogene low-rank coal from the Baise Coalfield, Guangxi Province, China: Contributions from surrounding terrigenous lithologies and the depositional environment, International Journal of Coal Geology, 214, 103282.
• [97] Dai, S., Ren, D., Chou, C.-L., Li, S., Jiang, Y., (2006), Mineralogy and geochemistry of the No. 6 coal (Pennsylvanian) in the Junger Coalfield, Ordos Basin, China. International Journal of Coal Geology, 66, 253–270.
• [98] Bau, M., Koschinsky, A., Dulski, P., Hein, J.R., (1996), Comparison of the partitioning behaviours of yttrium, rare earth elements, and titanium between hydrogenetic marine ferromanganese crusts and seawater. Geochimica Cosmochimica Acta, 60, 1709–1725.