Abstract: Repeated subduction of SN ocean crust under the North China continental crust and encroachment of sea water,and frequent rise and fall of the continental crust and alternate emergence of land and sea that created a swampy environment from early Paleozoic to late Permian contributed to the formation of conditions favourable for coalification.The difference of the magnitude of uplifting and subsidence between the southern and northern parts of North China and the ultimate downsinking of its central part laid the foundation of a depositional center in Central North China during the middle and early Triassic.It is pointed out that while they had undergone different process of development,the geologic structures of middle and lower Triassic owed their character to events occurring during the Carboniferous and Permian periods.The coal gas of Carboniferous and Permian periods was closely related to the Triassic Basin because the katogenic metamorphism of coal beds was largely completed by theend of Triassic.But,subsequent tectonic episodes occurring in the Triassic Bssin brought about many changes in its geologic features.All these must be taken into account in the study and exploration for coal gas.It is believedthat the most promising area for coal gas exploration is in the south of the Longhai railway where the thickness of coal measure approaches 1,000 meters.

摘要： 华北地区从早古生代时期至晚二迭世末期,经受几次南北向洋壳对华北陆壳的俯冲消减以及海水侵入,陆壳抬升与沉降频繁,海陆交替频繁,多次出现沼泽环境,给成煤造成有利条件。华北的南部及北部抬升与沉降的幅度不完全一致,但最终是南北部隆起,中部下沉,因此,华北中部是中下三迭统的沉积中心。中、下三迭统与石炭二迭系在发育史上既有不同点,又有明显的继承性。石炭二迭系煤成气之所以与大型三迭系盆地有密切相关,是因为煤层之一次深成变质主要完成于三迭纪末,但三迭系盆地在燕山期及喜山期又遭到了许多新的构造运动的影响,产生了许多新特点,已不是原来的盆地面貌,对煤成气进行勘探与研究中,对所有构造运动的影响均应加以考虑。在华北地区一般认为找气最有希望的地区是陇海线以南的南华北,该区煤系地层(太原组-上石盒子组)发育,厚度近千米,煤层累厚10-50米,成气物质雄厚,而北华北煤系地层(本溪组-山西组)厚度不足300米,煤层累厚5～25米,成气物质基础不如南华北煤系地层。