Striking liptinitic bark remains peculiar to some Late Permian Chinese coals

An unusual liptinite coal component has been reported in the Chinese literature over the past sixty years. It has been described as a maceral in the Chinese National Standard (1991), but it has not been named internationally. In Chinese literature it is called “barkinite”, on the basis of its morphological features and because it is believed to have originated as bark tissue.“Barkinite” occurs in Late Permian, marine-influenced coals and is best represented in the Changguang, Leping and Shuicheng Basins of southern China.The material originates from plant periderm or the bark of higher plants. However, “bark” contains a variety of substances, including resin and suberin, which are recognised as the precursors of the resinite and suberinite macerals. “Barkinite” is distinguished by (i) its thickness; individual pieces can be more than ten cells thick and several centimetres long and (ii) it fluoresces strongly at 0.6% vitrinite reflectance and loses its fluorescence at about 1.1% vitrinite reflectance.The reporting of “barkinite” from only Chinese coals may be due to its origin from Lepidodendron and Psaronius flora, which was common in the Northern Hemisphere during the Carboniferous, but which was isolated to China by the Late Permian. It is proposed that the remnant flora evolved into unique forms in China by the Late Permian. Lepidodendron and Psaronius remains, coupled with a strongly marine-influenced, peat-forming environment have given rise to “barkinite” and to its restricted distribution.     

Direct determination of the aliphatic carbon content of individual macerals in petroleum source rocks by near-infrared microspectroscopy

In order to determine the aliphatic carbon content in sedimentary organic particles near-infrared (NIR) microscope spectroscopy has been employed for the first time. An ordinary lens microscope photometer common for vitrinite reflectance measurements has been modified to detect hydrocarbon absorbance differences with a spatial resolution of about 30 μm.Microscopic studies of natural and artificial samples under reflected light condition were shown to be unsuitable for quantitative aliphatic C--- determination. Transmitted light measurements ofliptinites in polished thin sections, however, could be calibrated against synthetic polymer blends without exact knowledge of the sample thickness. In contrast to the established microscopic techniques for characterizing coal and petroleum source rocks NIR microspectroscopy is able to follow the chemical alterations of liptinites directly with comparatively low cost.