The Genetic Mechanism of Inertinite in the Middle Jurassic Inertinite-Rich Coal Seams of the Southern Ordos Basin

Dongdong Wang (College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao Shandong, 266590, China)
Qiang Mao (College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao Shandong, 266590, China)
Guoqi Dong (College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao Shandong, 266590, China)
Shipeng Yang (Shandong Institute of Geological Survey, Ji’nan Shandong 250013, China)
Dawei Lv (College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao Shandong, 266590, China)
Lusheng Yin (College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao Shandong, 266590, China)


Inertinite is an important type of organic maceral in coal deposits, andalso an important geological information carrier of coal forming environments. In the southern section of the Ordos Basin, the No. 4 inertinite-richcoal seam of the Middle Jurassic Yan’an Formation in the Binchang Coalfield was selected as an example to study the genetic mechanism of theinertinite. In this study, the results obtained from experimental tests ofcoal rock, including principal and trace elements, stable carbon isotopes,scanning electron microscopy, inertinite reflectance, sporopollen andfree radical retorting methods, were analyzed. Then, the findings werecombined with the previous understanding of the oxygen content in theatmosphere and ground fire characteristics, in order to discuss the genesismechanism of inertinite in the No. 4 coal seam. The obtained researchresults were as follows: (1) During the coal forming period of the No. 4coal seam, the overall climate had been relatively dry. There were fourrelatively dry-wet climate cycles in the No.4 coal seam, which werecontrolled by the eccentricity astronomical period. The inertinite contentwere relatively high during the dry periods; (2) The temperature rangesuitable for microorganism activities during the oxidation processes wasbetween 0 and 80℃ . The simulation results of the free radical concentrations showed that the maximum temperature of fusain in the No. 4 coalseam during the process of coalification had not exceeded 300℃ , whichwas significantly higher than the temperature range of microorganismactivities. Therefore, these were not conducive to the activities of microorganism and formation of inertinite during the coal-forming period;(3) The genesis temperature of the inertinite in the No. 4 coal seam wascalculated according to the reflectance of the inertinite, which was lowerthan 400 ℃ . This result supported the cause of wildfire of the inertiniteand reflected that the type of wildfire was mainly ground fire, along withpartially surface fire. Moreover, the paleogeographic location, climaticconditions, atmospheric oxygen concentration, etc. of the study areashowed that the conditions for wildfire events were in fact available; (4)There were dense and scattered fusinite observed in the No. 4 coal seam,and the thickness of cell walls were found to differ. It was speculated thatthis was related to the type of wildfire, combustion temperatures, combustion timeframes, and different initial conditions of the burned objectsduring the coal forming periods.


Inertinite-rich coal ;Wildfire events; Oxidation effects; Genetic mechanism ;Jurassic Period; Ordos Basin

Full Text:



[1] Stach E., Mackowsky M. T., Teichmüller M, et al. Stach’s Textbook of Coal Petrology, 3rd Ed [M]. Gebrfider Borntraeger, Berlin, 1982, 535.

[2] Taylor G. H., Liu S. Y. and Diessel C. F. K. The Cold-climate Origin of Inertinite-rich Gondwana Coals [J]. International Journal of Coal Geology, 1989, 11(1): 1-22

[3] DOI: 10.1016/0166-5162 (89)90110-9

[4] Singh M. P. and Shukla R. R. Petrographic Characteristics and Depositional Conditions of Permian Coals of Pench, Kanhan, and Tawa Vally Coalfields of Satpura Basin, Madhya Pradesh, India [J]. International Journal of Coal Geology, 2004, 59: 209–243.

[5] DOI: 10.1016/j.coal. 2004. 02.002

[6] Li X. Y. Conditions of Inertinite-rich Coal Generation,Shendong Mining area: Significance of Fungal Alternating Origin of Inerts [J]. Coal Geology & Exploration, 2005, 33(5): 1-4. DOI: 10.1360/gs050303

[7] Jasper A., Uhl D., Guerra-Sommer M, et al. Upper Paleozoic Charcoal Remains from South America: Multiple Evidences of fire events in the Coal bearing Strata of the Paraná Basin, Brazil [J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2011, 306: 205– 218. DOI: 10. 1016/j. palaeo.2011.04.022

[8] Jasper A., Guerra-Sommer M., Hamad A. M. B. A, et al. The Burning of Gondwana: Permian fires on the Southern Continent — A palaeo- botanical Approach [J]. Gondwana Research, 2013, 24: 148-160. DOI: 10.1016/ 08. 017

[9] Jasper A., Agnihotri D., Tewari R, et al. Fires in the mire: Repeated fire events in Early Permian ‘peat forming’ Vegetation of India [J]. Geological Journal, 2016, 52: 955-969. DOI: 10.1002/ gj.2860

[10] Manfroi J., Uhl D., Guerra-Sommer M, et al. Extending the database of Permian palaeo- wildfire on Gondwana: Charcoal remains from the Rio do Rasto Formation (Paraná Basin), Middle Permian, Rio Grande do Sul State, Brazil[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2015, 436: 77–84.

[11] DOI: 10.1016/ j.palaeo.2015.07.003

[12] Kauffmann M., Jasper A., Uhl D, et al. Evidence for palaeo- wildfire in the Late Permian palaeotropics — Charcoal from the Motuca Formation in the Parnaíba Basin, Brazil [J].

[13] Palaeogeography, Palaeoclimatology, Palaeo- ecology, 2016, 450: 122–128. DOI: 10.1016/ j.palaeo. 2016.03.005

[14] Wu C. R., Zhang H., Li X. Y, et al. Study on Coal Quality and Coal Metamorphism of Early-Middle Jurassic Coal Rocks in Northwest China [M]. Beijing: Coal Industry Press, 1995.

[15] Zhang X. Y., Tong Y. Z., Xiao D. X, et al. Discussion on the Genesis of Huangling Candle Coal [J]. Coalfield Geology of China, 1996(S): 10-16.

[16] Zhang J., Yu B. and Tang J. X. Characteristics andFacies of Ya-8 coal in Yining Coalfield, Xinjiang [J]. Coalfield Geology of China, 1999, 11(1): 30−32.

[17] Li W. H., Chen Y. F., Chen W. M, et al. Distribution

[18] Features of Micro-Constituents for Coal in China Main Mining Area [J]. Coal Science and Technology, 2000, 28(9): 31−34. DOI: 10.13199/ j.cst. 2000.09.34. liwh.011

[19] Zeng F. G. Petrographic Characteristics of Coal Seam No2-2 from Daliuta mine district, Shenfu area, North Shaanxi [J]. Coal Geology & Exploration, 2000, 28(3): 25−27. Bai X. F., Li W. H., Chen W. M, et al. Study on Distribution and Characteristics of coals with weak reductive degree in West china[J]. Journal of Coal Science, 2005, 30(4): 502−506. DOI: 10.13225/ j.cnki.jccs. 2005.04.021

[20] Chang H. Z., Zeng F. G., Li W. Y, et al. Micro-FTIR Study on Structure of Macerals from Jurassic Coals in Northwestern China [J]. Spectroscopy and Spectral Analysis, 2008, 28(7): 1535-1539.

[21] DOI: 10.1016/j.sab. 2008.04.017

[22] Huang W. H., Tang S. H., Tang X. Y, et al. The Jurassic coal petrology and the research significance of Northwest China [J]. Coal Geology & Exploration, 2010, 38(4): 1-6. DOI: 1001-1986 (2010) 04-0001-06

[23] Hower J. C., O’Keefe J. M. K., Watt M. A, et al. Notes on the origin of inertinite macerals in coals: Observations on the importance of fungi in the origin of macrinite [J]. International Journal of Coal Geology, 2009, 80(2): 135–143. DOI: 10.1016/ j.coal. 2009. 08.006

[24] Hower J. C., O’Keefe J. M. K., Volk T. J, et al. Funginite-resinite associations in coal [J]. International Journal of Coal Geology, 2010, 83(1): 64-72. DOI: 10.1016/j.coal.2010.04.003

[25] Teichmüller M. Vergleichende mikroskopische Untersuchungen versteinerter Torfie des Ruhrkarbons und der daraus entstanden Steinkohlen [C]. C. R., 3rd Carboniferous Cong, Heerlen, 1952: 607-613.

[26] Han D. X. Coal petrology in China [M]. Shanghai: East China Normal University Press, 1996.

[27] Harvey R. D. and Dillon J. W. Maceral distributions in Illinois coals and their paleoenvironmental implications [J]. Internation -al Journal of Coal Geology, 1985, 5(1-2): 141-165. DOI: 10.1016/ 0166-5162 (85) 90012-6

[28] Phillips T. L., Peppers R. A. and Dimichele W. A. Stratigraphic and interregional changes in Pennsylvanian coal-swamp vegetation: Environmental inferences[J]. International Journal of Coal Geology, 1985, 5(1-2): 43-109. DOI: 10.1016/ 0166-5162 (85) 90010-2

[29] Hunt J. W. and Smyth M. Origin of Inertinite-rich coals of Australian Cratonic Basins [J]. International Journal of Coal Geology, 1989, 11(1): 23-46. DOI: 10.1016/ 0166-5162(89) 90111-0

[30] Zhuang J. and Wu J. J. Middle Jurassic coal accumulation characteristics and coal comprehensive utilization of southern Ordos Basin [M]. Beijing: Geological Publishing House, 1996.

[31] Chen X. W., Zhuang X. G., Zhou J. B, et al. Coal Quality and its Distribution of the Eastern Junggar Coalfield in Junggar Basin, Xinjiang [J]. Xinjiang Geology, 2013, 31(1): 89-94. DOI: 10.3969/ j.issn. 1000-8845. 2013.01.019

[32] Hagelskamp H. H. B. and Snyman C. P. On the Origin of Low-reflecting Inertinites in Coals from the Highveld Coalfield, South Africa [J]. Fuel, 1988, 67(3): 307-313. DOI: 10.1016/ 0016-2361(88) 90311-0

[33] Moore T. A., Shearer J. C. and Miller S. L. Fungal

[34] origin of oxidised plant material in the Palangkaraya peat deposit, Kalimantan Tengah, Indonesia: Implications for ‘inertinite’ formation in coal [J]. International June Coal Geology, 1996, 30(1-2): 1-23. DOI: 10.1016/ 0166-5162(95) 00040-2

[35] Styan W. B. and Bustin R. M. Petrographyof some fraser river delta peat deposits: Coal maceral and microlithotype precursors in temperate-climate peats [J]. International Journal of Coal Geology,

[36] , 2(4): 321-370. DOI: 10.1016/ 0166-5162(83) 90016-2

[37] Scott A. C. Observation on the nature and origin of

[38] fusinite [J]. International Journal of Coal Geology, 1989, 12(1-4): 443-475. DOI: 10.1016/ 0166-5162(89) 90061-X

[39] Teichmüller M. The genesis of coal from the viewpoint of coal petrology [J]. International Journal of Coal Geology, 1989, 12(1-4): 1-87. DOI: 10.1016/ 0166-5162(89) 90047-5

[40] Austen D. E. G., Ingram D. J. E., Given P. H, et al. Electron sprin resouance study of pure macerals[J]. Coal Science, 1966, 55: 344-362. DOI: 10.1021/ ba-1966-0055. ch021

[41] Jones T. P. and Chaloner W. G. Fossil charcoal, its

[42] recongnition and palaeoatmospheric significance [J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 1991, 97(1-2): 39-50. DOI: 10.1016/ 0031-0182(91) 90180-Y

[43] Bustin R. M. and Guo Y. Abrupt changes (jumps) in reflection values and chemical compositions of artificial charcoals and inertinite in coals[J]. International Journal of Coal Geology, 1999, 38(3-4): 237-260. DOI: 10.1016/ S0166-5162(98) 00025-1

[44] Guo Y. and Bustin R. M. FTIR spectroscopy and

[45] reflectance of modern charcoals and fugnal decayed woods: implications for studies of inertinite in coals[J]. International Journal of Coal Geology, 1998, 37(1-2): 29-53. DOI: 10.1016/ S0166-5162(98) 00019-6

[46] Scott A. C. The Pre-Quaternary history of fire [J].

[47] Palaeogeography, Palaeoclimatology, Palaeoecology, 2000, 164: 281-329. DOI: 10.1016/ s0031-0182(00) 00192-9

[48] Petersen H. I. and LindstrÖm S. Synchronous Wildfire Activity Rise and Mire Deforestation at the Triassic–Jurassic Boundary [J]. Plos One, 2012, 7(10): e47236. DOI: 10.1371/ journal. pone. 0047236

[49] Uglik M. and Nowak J. L. Petrological recognition of bituminous inertinite enriched coals of the Lower Silesian Coal Basin(Central Sudetes, SW Poland) [J]. International Journal of Coal Geology, 2015, 139: 49–62. DOI: 10.1016/j.coal.2014.07.009

[50] Wang Z. Q. and Chen A. S. Traces of arborescent lycopsids and dieback of the forest vegetation in relation to the terminal Permian mass extinction in North China [J]. Review of Palaeobotany and Palynology, 2001, 117: 217–243. DOI: 10.1016/ S0034 -6667(01) 00094-X

[51] Sun Y. Z., Püttmann W., Kalkreuth W, et al. Petrologic and geochemical characteristics of seam 9–3 and Seam 2, Xingtai Coalfield, northern China [J]. International Journal of Coal Geology, 2002, 49: 251–262. DOI: 10.1016/ S0166-5162(01) 00067-2

[52] Yan M. X., Wan M. L., He X. Z, et al. First report

[53] of Cisuralian (early Permian) charcoal layers within a coal bed from Baode, North China with Reference to Global Wildfire Distribution [J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2016, 459: 394–408. DOI: 10.1016/j.palaeo.2016.07.031

[54] Sun Y. Z., Zhao C. L., Püttmann W, et al. Evidence

[55] of widespread wildfires in a coal seam from the middle Permian of the North China Basin [J]. Lithosphere, 2017, 9(4): 595-608.

[56] DOI: 10.1130/L638.1

[57] Uhl D. and Kerp H. Wildfires in the late Palaeozoic

[58] of Central Europe—The Zechstein (Upper Permian) of NW-Hesse (Germany) [J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2003, 199: 1–15. DOI: 10.1016/ S0031-0182(03) 00482-6

[59] Noll R., Uhl D. and Lausberg S. Brandstrukturen an

[60] Kieselhölzern der Donnersberg Formation (Oberes Rotliegend, Unterperm) des Saar-Nahe-Beckens (SW-Deutschland) [J]. Veröffentlichungen des Museums für Naturkunde Chemnitz, 2003, 26: 63–72.

[61] Uhl D., Lausberg S., Noll R, et al. Wildfires in the

[62] late Palaeozoic of central Europe — An overview of the Rotliegend (Upper Carboniferous–Lower Permian) of the Saar-Nahe Basin (SW-Germany) [J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2004, 207(1-2): 23–35. DOI: 10.1016/ j.palaeo. 2004.01.019

[63] Uhl D., Jasper A., Hamad A. M. B, et al. Permian and Triassic wildfires and atmospheric oxygen levels [C]. Proceedings, 1st WSEAS International Conference on Environmental and Geological Science and Engineering: World Scientific and Engineering

[64] Academy and Society, 2008: 179–187.

[65] Uhl D., Butzmann R., Fischer T. C, et al. Wildfires in the late Palaeozoic and Mesozoic of the Southern Alps — The late Permian of the Bletterbach-Butterloch area (northern Italy) [J]. Rivista Italiana di Paleontologia e Stratigrafia, 2012, 118(2): 223–233.

[66] DOI:10.13130/ 2039-4942/ 6002

[67] Scott A. C. Coal petrology and the origin of coal macerals: a way ahead [J]. International Journal of Coal Geology, 2002, 50(1-4): 119-134. DOI: 10.1016/ S0166-5162(02) 00116-7

[68] Scott A. C. and Glasspool I. J. Observations and Experiments on the Origin and Formation of Inertinite Group Macerals [J]. International Journal of Coal Geology, 2007, 70(1-3): 53-66.

[69] DOI: 10.1016/ j.coal. 2006.02.009

[70] Diessel C. F. K. The Stratigraphic Distribution of Inertinite[J]. International Journal of Coal Geology, 2010, 81(4): 251–268.

[71] DOI: 10.1016/ j.coal. 2009. 04. 004

[72] Wang D. D. Sequence-palaeogeography and Coal-accumulation of the Middle Jurassic Yan’an Formation in Ordos Basin [D]. Beijing: China University of Mining and Technology, 2012: 224-225.

[73] Vakhrameev V. A. Range and Paleoecology of Mesozoic Conifers, Cheirolepidiaceae [J]. Paleontological Journal, 1970, 70(1): 19-34.

[74] Miao S. J. Spore pollen, Mesozoic Strata and Paleontology in the Coal bearing Strata of Guyang, Inner Mongolia [M]. Beijing: Geological Publishing House,1982.

[75] Duan Z. H. Classopollis pollen and its paleoclimate

[76] meaning[J]. Coal Geology and Exploration, 1991, 19(6): 14-21.

[77] Qian. L. J. and Wu J. J. The Jurassic Spore pollenCombination in the Northwestern Shaanxi, The Jurassic Coal-bearing Strata and coal Accumulation Characteristics in the Northwestern Shaanxi [M].

[78] Xi’an: Northwest University Press, 1987.

[79] Zhou C. G., Yang Q., Pan Z. G, et al. Paleo-climate

[80] Evolution of Yan’an Stage Inferred from Petrographic Composition of Coal [J]. Coal Geology of China, 1996, 8(4): 12-14+19.

[81] Yang Q. and Han D. X. Coalfield Geology of China [M]. Beijing: Coal Industry Press, 1979.

[82] Wang D. D., Yan Z. M., Liu H. Y, et al. The net primary productivity of Mid-Jurassic peatland and its control factors: Evidenced by the Ordos Basin [J]. International Journal of Mining Science and Technology, 2018, 28(2): 177-185.

[83] DOI: org/ 10.1016/ j.ijmst. 2017.06.001

[84] Fang A. M., Lei J. J., Jin K. L, et al. An Anthracographic Study on No.7 Coal in Xishan Coalfield, Shanx [J]. Coal Geology of China, 2003, 15(5): 12-16.

[85] Wang D. Z. A Study on No.5 Coal Seam Facies, Huating Mining Area [J]. Coal Geology of China, 2005, 17(4): 6-8+70.

[86] DOI: 10.3969/ j.issn. 1674-1803. 2005.04.003

[87] Li Q. Coal facies of No.2 coal in Yanchuannan coal field of Shanxi: Significance for constituencies of coalbed methane exploitation [J]. Petroleum Geology & Experiment, 2014, 36(2): 245-248+256. DOI: 10.11781/ sysydz 201402245

[88] Fan Y. H., Qu H. J., Wang H, et al. The application

[89] of trace elements analysis to identifying sedimentary media environment: a case study of Late Triassic strata in the middle part of western Ordos Basin [J]. Geology in China, 2012, 39(2): 382-389. DOI: 10.1016/ j.still. 2012.05.017

[90] Wang S. J., Huang X. Z., Tuo J. C, et al. Evolutional Characteristics and Their Paleocl imate Signif icance of Trace Elements in the Hetaoyuan Formation, Biyang Depression [J]. Acta Sedimentologica Sinica, 1997, 15(1): 66-71. DOI: 10.14027/ j.cnki.cjxb. 1997.01.012

[91] Hu X. F,, Liu Z. J., Liu R, et al. Trace Element Characteristics of Eocene Jijuntun Formation and the Favorable Metallogenic Conditions of Oil Shale in Fushun Basin [J]. Journal of Jilin University(Earth Science Edition), 2012, 42(S1): 60-71.

[92] DOI: 10.13278/ j.cnki.jjuese. 2012.s1.008

[93] Zhang B. and Yao Y. M. Trace Element and Palaeoenvironmental Analyses of the Cenozoic Lacustrine Deposits in the Upper Es4 Submember of the Dongying Basin [J]. Journal of Stratigraphy, 2013, 37(2): 186-192.

[94] Teng G. R., Liu W. H., Xu Y. C, et al. The Discussion on Anoxic Environments and Its Geochemical Identifying Indices [J]. Acta Sedimentologica Sinica, 2004, 22(2): 365-372. DOI: 10.3969/j.issn. 1000- 0550. 2004.02.026

[95] Liang W. J., Xiao C. T. and Xiao S. Study on Relationships between Paleoenvironment, Paleo- climate of Middle Permian-middle Triassic and Constant, Trace Elements in Western Sichuan [J]. Science Technology and Engineering, 2015, 15(11): 14-24.

[96] Zhao X. W. Introduction to Paleoclimatology [M]. Beijing: Geological Publishing House, 1992.

[97] Lu J., Shao L. Y., Wang Z. G, et al. Organic carbon isotope composition and paleoclimatic evolution of Jurassic coal seam in the northern Qaidam basin [J]. Journal of China University of Mining & Technology, 2014, 43(4): 612-618. DOI: 10.13247/ j.cnki.jcumt. 000091

[98] Lu J., Yang M. F., Shao L. Y, et al. Paleoclimate change and sedimentary environment evolution, coal accumulation: A Middle Jurassic terrestrial [J]. Journal of China Coal Society, 2016, 41(7): 1788-1797. DOI: 10.13225/ j.cnki.jccs. 2016. 0061

[99] Large D. J. A 1.16 Ma record of carbon accumulation in western European peatland during the Oligocene from the Ballymoney lignite, Northern Ireland [J]. Journal of the Geological Society, 2007, 164(6): 1233-1240. DOI: 10.1144/ 0016-76492006-148

[100] Large D. J., Jones T. F., Somerfield C, et al. High-resolution Terrestrial Record of Orbital Climate Forcing in Coal [J]. Geology, 2003, 31(4): 303-306. DOI: 10.1130/ 0091-7613 (2003)031 <0303: HRTROO> 2.0.CO;2

[101] Li X. Q., Zhang S. C., Zhu G. Y, et al. Types and Research Direction of Biogenic Gas in China [J]. Natural Gas Geoscience, 2005, 16(4): 477-484.

[102] Scott A. C. and Jones T. P. The Nature and Influence of fire in Carboniferous Ecosytems [J]. Palaeogeography,Palaeoclimatology, Palaeoecology, 1994, 106(1-4): 91-112. DOI: 10.1016/ 0031-0182 (94) 90005-1

[103] Glasspool I. J. and Scott A. C. Phanerozoic Concentrations of Atmospheric Oxygen Reconstructed from Sedimentary Charcoal [J]. Nature Geoscience, 2010, 3(9): 627-630. DOI: 10.1038/ ngeo923

[104] Jones T. P. Fusain in Late Jurassic Sediments from Witch Ground Graben, North Sea [J]. U.K, Mededelingen Nederlands Instituut voor Toegepaste Geowetenschappen TNO, 1997, 58: 93–103.

[105] Zhang J. L. and Di X. Y. The Study of Ground Fire and Smoldering: A Review [J]. Journal of Temperate, 2018, 1(3): 19-23. DOI: 10.3969/ j.issn. 2096-4900. 2018.03.004

[106] Shu L. F., Wang M. Y., Tian X. R, et al. Fire Environment Mechanism of Ground fire Formation in Daxing’ an Mountains [J]. Journal of Natural Disasters, 2003, 12(4): 62-68. DOI: 10.13577/ j.jnd. 2003.0411

[107] Rein G., Cleaver N., Ashton C, et al. The Severity of Smouldering Peat Fires and Damage to the Forest Soil [J]. Catena, 2008, 4(3): 304-309. DOI: 10.1016/ j.catena. 2008.05.008

[108] Wang H. R., Liang D., Zhan G. T, et al. Spontaneous Combustion Characteristics of Peat under Low Temperature [J]. Fire Science and Technology, 2018, 37(2): 171-174. DOI: 10.3969/ j.issn. 1009-0029. 2018.02.007



  • There are currently no refbacks.
Copyright © 2020 Dongdong Wang, Qiang Mao, Guoqi Dong, Shipeng Yang, Dawei Lv, Lusheng Yin

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.