灵武煤田煤中镜质组与丝质组的甾萜类化合物对比研究

本文对灵武煤田含煤岩系延安组煤岩显微组分的甾萜类化合物作了对比研究．结果表明,同一沉积环境中镜质组与丝质组的甾萜类化合物特征及不同沉积环境中同一显微组分（镜质组或丝质组）的甾萜类化合物特征有着规律性的变化．     

Paleo‐fires and Atmospheric Oxygen Levels in the Latest Permian: Evidence from Maceral Compositions of Coals in Eastern Yunnan,Southern China

Inertinite maceral compositions of the Late Permian coals from three sections in the terrestrial and paralic settings of eastern Yunnan are analyzed in order to reveal the paleo-fire events and the atmospheric oxygen levels in the latest Permian. Although the macerals in the studied sections are generally dominated by vitrinite, the inertinite group makes up a considerable proportion. Its content increases upward from the beginning of the Late Permian to the coal seam near the Permian-Triassic boundary. Based on the microscopic features and the prevailing theory that inertinite is largely a by-product of paleo-fires, we suggest that the increasing upward trend of the inertinite abundance in the latest Permian could imply that the Late Permian peatland had suffered from frequent wildfires. Since ignition and burning depend on sufficient oxygen, a model-based calculation suggests that the O2 levels near the Wuchiapingian/Changhsingian boundary and the Permian-Triassic boundary are 27% and 28% respectively. This output adds supports to other discoveries made in the temporal marine and terrestrial sediments, and challenges the theories advocating hypoxia as a mechanism for the Permian-Triassic boundary crisis.     

显微组分大分子结构演化差异性及其动力学机制——研究进展与展望

显微组分物理化学性质是影响煤炭清洁高效利用和煤储层物性的重要因素,已经认识到决定显微组分性质的根本原因在于其大分子结构。为了揭示显微组分大分子结构演化特征及其控制因素,从显微组分大分子化学结构与物理结构、大分子结构演化的构造应力效应、煤变质全阶段大分子结构演化特征等方面,总结了国内外研究进展,分析了存在的不足。指出由于富镜质组煤的广泛分布和重要工业用途使之成为煤结构研究的主要对象,惰质组的研究则相对缺乏,阻碍了对煤特性的全面认识。提出“煤变质作用的热-应力条件决定显微组分结构演化、惰质组与镜质组大分子结构演化具有差异性”的研究思路,采用惰质组/镜质组高温高压模拟和热模拟实验并与自然序列变质-变形煤对比,研究显微组分结构演化特征及其控制因素。定量刻画显微组分大分子结构与温压条件的关系,揭示构造应力对显微组分化学结构和纳米孔隙结构的控制,确定煤变质全过程中惰质组大分子结构的演化路径,建立惰质组大分子动力学模型。上述研究成果将充实对煤微观结构演化及其控制因素的全面认识,为煤炭清洁高效利用和煤储层物性评价提供基础依据。      

煤炭显微煤岩组分与工业分析关系研究

通过分析宁夏各煤田中部分具有代表性煤矿勘查阶段钻孔煤岩煤样测试数据,研究了煤的显微煤岩组分与工业分析之间的关系。随着煤中有机组分、无机组分含量的变化,煤的灰分、挥发分、固定碳发生变化。煤中有机组分含量大于90%时,煤中灰分与黏土类含量存在正相关,挥发分与惰质组和壳质组含量均存在正相关,且惰质组含量影响更大;有机组分含量小于90%时,煤中灰分与惰质组和黏土类含量均存在正相关,且惰质组含量影响更大,挥发分与壳质组含量存在正相关。煤中固定碳含量受镜质组含量影响最大,二者存在正相关。     

煤中显微组分的成烃演化实验

热解模拟实验揭示,镜质组的生烃作用与其起始成熟度有关,如果初次生烃中止,成熟度 (再次生烃起始成熟度)尚未超过生油高峰阶段 (R=0.9%),则再次生烃有可能显著提高煤的生烃潜量,且以起始成熟度在生烃高峰处的升高幅度为最大。在有机显微组分中:壳质组的生烃量最大,生烃范围最集中;镜质组次之;惰质组最少。      

Secretinite—reflectance and chemical data from two high volatile bituminous coals (Upper Carboniferous) of North America

Secretinite—a maceral of the inertinite group as recognized by the ICCP in 1996—is a noncellular maceral of seed fern origin. New reflectance data indicate that this maceral has primary anisotropy with bireflectances of 0.4% to 0.9% in high-volatile B bituminous (Ro=0.6%) Carboniferous coal of North America. The highest reflectance is in cross-section as opposed to longitudinal section. Characteristic feature of secretinite is the virtual absence of Si and Al, unlike that in associated vitrinite. This indicates the absence of submicron aluminosilicates in secretinite and their presence in vitrinites. Secretinite is highly aromatic as indicated by low O/C ratios and high contribution of aromatic hydrogen bands detected by FTIR analysis.     

Organic petrography and geochemistry of inertinite-rich mudstones, Jakobsstigen Formation, Upper Jurassic, northeast Greenland: Indications of forest fires and variations in relative sea-level

The lower-middle Oxfordian Jakobsstigen Formation, Wollaston Forland, northeast Greenland, consists mainly of stacked coarsening-upward successions of offshore to shoreface heteroliths, sandstone and rare foreshore sandstones. The units are separated by thin, laterally extensive sheets of terrigenous carbonaceous mudstones, which have been subjected to organic petrographic and geochemical studies. The mudstones are thermally immature, with maturities corresponding to R₀ in the range 0.35–0.50%. The mudstones contain very high proportions of allochthonous inertinite, subordinate huminite, char and negligible proportions of liptinite. Inertinite reflectance distributions are markedly bimodal, with maxima at approximately 1.73 and 4.91% R_m. Both pyrolysis yields and solvent extract yields are low. The distributions of n-alkanes are markedly light-end skewed and show a pronounced predominance of even-numbered compounds in the lower carbon number range. Biomarker-distributions feature a dominance of C₂₉-steranes, slight enhancement of extended hopanes and αββ-steranes, low proportion of tricyclic triterpanes and very low hopane/sterane ratios. Sedimentological, organic petrographical and geochemical evidence suggests that the regular alternation between marine and terrestrial depositional environments during deposition of the Jakobsstigen Formation was related to low-amplitude, high-frequency changes in relative sea-level and local climate. The mudstones were deposited during early rise of relative sea-level in shallow, flat-bottomed lakes or lagoons on a broad coastal plain. The lakes acted as traps for fine elastic sediment and for predominantly windborne inertinite, generated by wildfires in the hinterland. High rates of evaporation rendered the lakes mildly saline, hampering their colonization by vegetation other than cyanobacteria and halophilic microorganisms. Similarly, saline porewaters excluded higher plant vegetation from emergent areas. Upon continued rise of the relative sea-level, the lakes were gradually flooded and their deposits became covered by sandy shallow marine sediments. The larger areas covered by shallow marine waters during periods of high relative sea-level led to a more humid local climate and to lower frequency of wildfires. During falling relative sea-level, the marine deposits were eroded and partially removed and the cycle subsequently repeated upon renewed rise in relative sea-level. Hence, minor changes in relative sea-level gave rise to the regular alternation of two vastly different depositional environments, as well as to marked variations in local climate.