Paleozoic strata are widespread in the Xishan Coalfield,Shanxi,the central part of Trans-North China Craton.The coalfield is composed of the Cambrian - Middle Ordovician epicontinental carbonate sediments,the Late Carboniferous to Early Permian coal-bearing marine and terrestrial sequence and the Late Permian to Triassic red beds and conglomerates.The Late Paleozoic strata include the Late Carboniferous Benxi and Taiyuan Formations,the Early Permian Shanxi and Xiashihezi Formations,and the Late Permian Shangshihezi and Shiqianfeng Formations.At the west of Xishan coalfield,the Huyanshan syenitic-monzonitic complex emplaced at 135～91Ma (Yang et al.,1989).