华北西缘太原组火山事件沉积的发现及太原组地层对比

DISCOVERY OF VOLCANIC EVENT DEPOSITS AND STRATIGRAFIC CORRELATION OF TAIYUAN FORMATION IN WESTERN MARGIN OF NORTH CHINA

作者主要依据镜下岩矿特征，辅以岩石的野外产状与分布特点，并参考ＲＥＥ配分模式特征，首次发现华北西缘太原组存在３个火山事件层。根据火山事件沉积并结合最大海侵事件层对华北西缘太原组进行了区域对比．

ince 1965, the authors have found several beds of pyroclastic rock (acid or mediumacid crystal and vitric fragments), sed pyroclastic rock (tuffite) and pyroclastic sedimentary rock (tuffaceous limestone, tuffaceous sandstone, etc. ) in Taiyuan Formation of the western margin of North China. These beds belong to the early, middle and late volcanic event deposits of the Late Carboniferous respectively. These tuffs and tuffites are characterized by very thin beds and wide distribution. There are crystal fragments of indented quartz, chevron feldspar, darken biotite, fusiform and semi-plastic devitrified vitric fragments, and acid and medium--acid pyroclastic rock fragments. Their REE pattern also belongs to the pyroclastic type. On the basis of volcanic event deposits combined with maximum trangressive event deposits, the Taiyuan Formation in the western margin of North China was correlated regionally. The widest distribution of volcanic event beds is in the middle part of Taiyuan Formation. The middle part of the formation generally contains thick coalbeds. From the west to east, the thickness of the formation are obViously small,but their coal-bearing properties is better. The research results show that the volcanic event is mainly of eruption type. Pyroclasts were transported by winds, fell in water basin and deposited after hydrodynamic reworking with different strength. The volcanic ash might come from the north of Wuda district.