James C. Hower, Susan M. Rimmer, Maria Mastalerz, Nicola J. Wagner. Migmatite-like textures in anthracite: Further evidence for low-grade metamorphic melting and resolidification in high-rank coals[J]. Geoscience Frontiers, 2021, 12(3): 101122. DOI: 10.1016/j.gsf.2020.12.004
Citation: James C. Hower, Susan M. Rimmer, Maria Mastalerz, Nicola J. Wagner. Migmatite-like textures in anthracite: Further evidence for low-grade metamorphic melting and resolidification in high-rank coals[J]. Geoscience Frontiers, 2021, 12(3): 101122. DOI: 10.1016/j.gsf.2020.12.004

Migmatite-like textures in anthracite: Further evidence for low-grade metamorphic melting and resolidification in high-rank coals

  • Previous studies demonstrated that melting, initiated by supercritical fluids in the 375-400℃ range, occurred as part of anthracite metamorphism in the Appalachian Basin. Based on the known behavior of vitrinite at high temperatures and, to a lesser extent, at high pressures, it was determined that the duration of the heating, melting, and resolidification event was about 1 h. In the current study, featureless vitrinite within banded maceral assemblages demonstratesthe intimate association of melted and resolidified vitrinite with anthracite-rank macerals. By analogy with metamorphosed inorganic rocks, such associations represent diadysites and embrechites, i.e., cross-cutting and layered migmatites, respectively. Even though the temperature of formation of the anthracite structures is several hundred℃ lower than that seen in metamorphosed inorganic rocks, anthracites are metamorphic rocks and the nomenclature for metamorphic rocks may be appropriate for coal.
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