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In this contribution, we report the palynology, organic petrography and carbon isotopes for the #16 Seam in the Lower Cretaceous Yimin Formation of the Hailar Basin, Inner Mongolia, China. Eighteen palynological samples were collected from the coal seam as well as from intraseam partings and the immediate roof. Microfloras comprise a diverse assemblage of ferns, conifers, horsetails, lycopsids, bryophytes, ginkgoes and cycads. Conifer pollen is common, especially representative of Pinaceae (Pinuspollenites) as well as Cheirolepidiaceae (Classopollis) and Araucariaceae (Araucariacites, Chasmatosporite s); however, this material is interpreted as mostly derived from an upland source rather than from the mire-forming vegetation. An overrepresentation of conifer pollen may explain the relatively poor abundance and diversity of ginkgo and cycad pollen, compared to what is found in the macrofossil record. The palynological assemblage found in Seam #16 indicates a Barremian to Aptian age. Maceral composition, ash yields, and δ13C org signature of the coal suggest peat accumulation was controlled by a rising water table from flooding of the mire, coupled with significant ground (peat) fires and/or surface wildfires. These conditions resulted in high levels of detrital mineral matter and charcoal input, the latter represented by inertodetrinite in the coals. The top of the coal seam is characterised by a higher ash yield, lower δ13C org values and increased sphagnacean spores, which suggest the gradual drowning of the palaeomire. Although angiosperms were present in the Hailar Basin during the time that Seam #16 was accumulating, they are absent from the pollen found in this study. This may indicate that they were not yet adapted to the extreme conditions of the mire (e.g., acidity, anoxia), and unable to compete with the established mire vegetation. • Abundant fossil charcoal in the Seam #16 shows fire as an important part of palaeomire ecology. • Ash yields and δ13C org values indicate that flooding terminated the palaeomire. • Some pollen was likely derived from upland conifer forests and transported into the mire. • The absence of angiosperms reflects the harsh, palaeomire conditions. [ABSTRACT FROM AUTHOR]

Peat depositional environments, the sites where and conditions under which peat accumulates, significantly influence a resultant coal's physical properties, chemical composition, and coal utilization behavior. Recognition of peat depositional environments for coal is a challenging endeavor because coal's observed compositional properties not only result from a variety of geological processes operating during peat accumulation, but also reflect the influence of adjoining or external depositional sedimentary environments and alteration during later diagenesis and/or epigenesis. The maceral or microlithotype composition of any one layer of peat can be the product of years or decades of plant growth, death, decay, and post-burial infiltration by roots in addition to the symbiotic, mutualistic, parasitic, and saprophytic relationships with non-plant biota, such as arthropods, fungi, and bacteria. The overprint of increasing thermal maturation and fluid migration through time on the resulting coal can make these relationships difficult to recognize. Therefore, published models based on maceral composition alone must be used with great caution. Lipid compositions, even from lipid-poor low-rank coals, can provide important information about depositional environments and paleoclimate, especially if combined with the results of organic petrography and paleontological studies. Just as sulfur derived from seawater provides environmental clues, the ratios of two particularly relevant trace elements rather than a single trace element can be used to interpret peat depositional environments. Epigenetic minerals, as well as their corresponding chemical compositions should not be used for such a purpose; similarly, resistant terrigenous minerals deposited during peat accumulation in many cases should be used with considerable caution. The interactions of the biota present in the peat-forming ecosystem, often determined using palynological and geochemical proxies, and their interpretation in the context of geography and paleoclimate are important means for deciphering peat depositional environments. Overall, a combination of evidence from geochemistry, mineralogy, palynology, and petrology of coal and from stratigraphy, sedimentology, and sedimentary facies of related rocks is necessary for accurate and comprehensive determination of depositional environments. The need for interdisciplinary studies is underscored by peat compositional properties, which have been greatly affected by various processes during the syngenetic, diagenetic or epigenetic stages of coal formation. [ABSTRACT FROM AUTHOR]