The net primary productivity of early Permian peatland and their control factors: evidenced by the no. 6 coal seam of Jungar coalfield in North China

摘要

Purpose - The purpose of this paper is to take the early Permian no.6 coal seam in Jungar coalfield of North China as an example, this paper studied the net primary productivity (NPP) level of the early Permian peatland and its relationship with the atmospheric environment at that time, analyzed the influence of the atmospheric environment, and discussed its control factors. Design/methodology/approach - First, geophysical logging signals were used for a spectrum analysis to obtain the Milankovitch cycle parameters in the no. 6 coal seam, including the eccentricity (95 ka); obliquity (35.6 ka); and precession (21.2 ka). These were then used to calculate the accumulation rate of the residual carbon in the no. 6 coal seam, which was determined to be between 49.44 and 50.57 gC/(m~2 • a). The carbon loss could be calculated according to the density and residual carbon content of the no. 6 coal seam. Then, the total carbon accumulation rate of the peatland was further derived as being between 64.91 and 66.40 gC/(m~2·a). Also, the NPP of the peatland was determined to be between 129.82 and 132.8 gC/(m~2·a). Finding - The result showed that the NPP of the early Permian peatland area was lower than that of the Holocene at the same latitude, and also lower than that of the later Permian of South China. Originality/value - This study's comprehensive analysis indicated that the temperature and humidity conditions, along with the oxygen and carbon dioxide levels in the atmosphere, were the main control factors of the NPP of the early Permian peatland. Also, wildfires were found to play a role.