Petrology, mineralogy and geochemistry of the Permian and Triassic coals in the Leping area, Jiangxi Province, Southeast China

Permian and Triassic coals from a series of mines in Jiangxi Province, China, exhibit a number of unusual geochemical, mineralogical, and petrographic characteristics. The high volatile bituminous Permian coals have high concentrations of the suberinite-like maceral "barkinite." The origin, and even the distinct character, of "barkinite" are in dispute and, consequently, it has not been recognized as a distinct maceral by the International Committee for Coal and Organic Petrology (ICCP). The Permian bituminous coals have relatively high concentrations of pyrite and marcasite. Otherwise, detrital minerals dominate their geochemistry. The Triassic coals, all from one mine complex, have higher rank (a Permian coal is also mined). Most samples straddle the low volatile bituminous/semi-anthracite boundary. The one semi-anthracite-rank Permian coal shows signs of incipient coking. A Triassic coal in the same fault block is coked by an igneous intrusions found in the mine. The coals have, in general, been dolomitized. Aside from the geochemical imprint of the dolomitization, trace element associations suggesting a contribution from a detrital mineral assemblage dominate the coals.