川北晚三叠世须家河期古气候及成煤特征

川北晚三叠世须家河组植物化石含量丰富，根据喜湿植物，喜热植物在各段的厚分含量统计，须家河组整个沉积阶段气候温暖，潮湿与干旱（或半干旱）气候交替出现。喜湿与喜热植物纵向变化曲线图说明，从须Ｉ段至Ｖ段喜湿植物含量逐渐增高，喜热植物含量逐渐减少，随着湿度增大，温睛度下降则有得盱的形成，须Ⅲ段与须Ｖ段沉积阶段，为最佳成煤时期。须家河组可划分为２个煤组，３次成煤期，４种类型沉积环境，３种类型成煤植物。

PALEOCLIMATE AND COAL-FORMING CHARACTERISTICS OF THE LATE TRIASSIC XUJIAHE STAGE IN NORTHERN SICHUAN

There are abundant fossil plants in the Late Triassic Xujiahe Formation in northern Sichuan. According to the statistics of the percentages of thermophilic and hygrophilous plants in various members, the warm humid climate alternated with the arid (or semi-arid) climate throughout the deposition stage of the Xujiahe Formation. As shown by the chart of the vertical change of thermophilic and hygrophilous plants, the contents of thermophilic plants gets higher progressively and the content of hygrophilous plants gets lower from the first member to the fifth member of the Xujiahe Formation. Moisture increase and temperature decrease were favorable for coal formation. The deposition stages of the third and the fifth members were the best coal-forming periods. Two coal measures, three coal-forming stages, four kinds of sedimentary environments and three types of coal-forming plants may be distinguished on the basis of a study of the Xujiahe Formation.