THE CHARACTERISTICS OF VOLCANIC EVENT DEPOSITS AND THEIR TEMPORAL-SPATIAL DISTRIBUTION OF BENXI AND TAIYUAN FORMATIONS IN NORTH CHINA PLATFORM(NCP)

From a study of a good number of coal fields and coal mines of the North China Platform, 12 volcanic event layers which can be grouped into 6 stages have been discovered by the authors in Benxi and Taiyuan Formations.These volcanic event deposits are wide spread in the region and consist mainly of turfs, tuffites and tuffaceous sedimentary rocks. There is some regularity in their temporal-spatial distribution.The volcanic fragments were probably from different volcanic sources to the north and south of North China Platform and the magma of volcanic matter was, maybe, from the lower crust.