The Paleozoic craton basin in North China was developed on a stable pre-Sinian basement. Before the Carboniferous-Permian coal-bearing basins developed, the early Paleozoic craton was formed. Extensive Caledonian movement caused the basin to rise to land in the late Middle Ordovician, and was denuded and leveled, and then fell again in the late Carboniferous to accept deposition. Before sedimentation, the basement was mainly carbonate rocks of Middle Ordovician, and the basin margin gradually changed into Cambrian, Sinian or older rock series. The denuded and leveled open coastal plain extends to the northwest-southeast direction. In the early Late Carboniferous (Benxi stage), the North China landmass was at the ancient latitude of 8 ~18 N, which belonged to a tropical-subtropical warm and humid climate. Seawater invaded in the east, forming lagoons and tidal flat deposits in the bay, adjacent to the open shallow sea in the southeast, forming quasi-carbonate platform deposits, and the wide and gentle tidal flat in the northeast, forming submerged swamps, and the coal accumulation conditions are generally poor. In the late Late Carboniferous (Taiyuan period), seawater still invaded from the southeast, and Xuzhou and Huainan were adjacent to shallow seas, forming quasi-carbonate platform deposits. The low hills and ancient lands south of Sanmenxia, Xinzheng and Huaiyang in the southwest are submerged by seawater. The northern margin of the ancient land continued to uplift, and the continental margin debris was continuously injected into the bay lagoon, forming delta front estuary bar deposits. Due to the warm and humid paleoclimate and lush vegetation, peat swamp deposits were formed in the low-lying areas of the broad and gentle delta plain. The seawater began to recede in the late Late Carboniferous, and the seawater that retreated to the southeast in the early Early Permian (Shanxi period) moved the lagoon to Juxian and Huainan. The northern part of Tangshan-Shijiazhuang line is a fluvial facies area, and the ancient land on the northern margin is the provenance. Pingquan and Beijing are the main rivers, forming braided rivers to the south, forming the eastern delta plain, starting from Linfen in the west and reaching Zhengzhou in the south, forming the western delta plain, and forming a vast delta plain facies area in the middle of North China. Between the two delta plains, the tidal action is obvious, and the tidal flat sedimentary facies belt is formed in Dongming area. Shanxi's paleoclimate is still warm and humid, with lush vegetation, forming a large area of peat swamp deposits. From the late Early Permian (Lower Shihezi Stage) to the early Late Permian (Upper Shihezi Stage), seawater has withdrawn, and only a few brief transgressions occurred in the middle and late Upper Shihezi Stage, and marine interbeds appeared, which had little impact. The whole basin is dominated by river facies and delta plain facies, and the delta plain facies keeps moving southward. In the lower Shihezi period, it retreated to the south of Sanmenxia, Puyang and Jinan, and in the upper Shihezi period, it retreated to the south of Zhengzhou and Xuzhou, and the inter-branch swamp also kept moving southward. At present, the paleogeomorphology is still high in the northwest and low in the southeast, and the ancient land in the northern margin is still the material source. The paleoclimate has gradually changed from warm and humid to dry and hot, and there is no well-developed peat swamp facies deposition. In the late Late Permian (Shiqianfeng period), continental lakes and rivers were all over the region. The central and northern parts are river facies areas, and the southern part is lake facies areas. Due to the uplift of Dabie ancient uplift, the provenance mainly comes from the southern margin of the basin. Sanmenxia, Xinzheng and Pingdingshan form a group of alluvial fans distributed intermittently in the northwest, which are staggered and vertically superimposed. Due to the hot and dry paleoclimate and undeveloped vegetation, good peat swamp deposits and coal measures strata were not formed.

The coal measures in the Carboniferous-Permian coal-bearing basin in North China are the Upper Carboniferous benxi formation and Taiyuan Formation, the Lower Permian Shanxi Formation and the Lower Shihezi Formation, and the Upper Permian Upper Shihezi Formation. The thickness of coal measures is 250 ~1000m.

The lithofacies palaeogeography of Benxi stage is dominated by bay lagoon subfacies, which are distributed in Shijiazhuang, Tianjin, Jinan, Handan and Shangqiu, with a NW-SE distribution, covering an area of 25× 104 km2. There are shallow coastal tidal flat subfacies around it, which are distributed in Jinxi, Beijing, Zhengzhou, Lu Yi and other places. Quasi-carbonate platform subfacies are only distributed in Yiyuan, Yanzhou and Xuzhou areas in the southeast, and are in the transitional zone from coastal to shallow sea. There are water-covered swamps, carbonaceous mudstone and thin coal seams on the beaches in the northeast coast, such as flaky water-covered swamps in Qinhuangdao, Wen 'an, Huanghua and Jiyang.

The lower member of benxi formation is grayish brown bauxite and bauxite mudstone with lenticular hematite layer, while the upper member is grayish black shale, silty shale with powder, fine sandstone, bioclastic limestone and thin coal seam, which is rich in fossils and 4.3~83.9 meters thick, and is unconformity with the underlying stratum. Tangshan area in the northeast of the basin is 40 ~ 60 m thick, and the Sanmenxia-Xinzheng-Huaiyang line in the south is missing. Generally, it does not contain minable coal seams, and the thin coal seams in Tianjin, Huanghua and Kenli are 2 ~ 6 m thick.

Lithofacies palaeogeography of Taiyuan period inherited the basic characteristics of Benxi period. With the expansion of transgression, the south of Huanghua-Baoding line is a vast and flat lagoon, and the sea water gradually becomes deeper from northwest to southeast. Xuzhou, Huaiyang and Huainan are shallow sea areas, forming quasi-carbonate platform subfacies, which are thin in northwest and thick in southeast. Due to the uplift of the ancient land in the northern margin, fluvial facies and delta facies deposits were formed. The fluvial facies is distributed in the north of Jinchang line, Chengde forms the main channel, and the rest are alluvial plain facies deposits. From south to north of Huanghua-Baoding line, delta plain and braided distributary channel deposits are distributed in Chengde, Tangshan, Jinghai, Kenli and Binxian. Beijing, Baxian, Tianjin, Tangshan, Kenli, Zhanhua and Qinhuangdao belong to the inter-branch plain and inter-branch swamp facies belt, and the thickness of coal seam accounts for 15% of the thickness of sedimentary rocks. South of Huanghua-Baoding line is lagoon facies area, where the delta front Shahekou bar deposits are distributed, and two estuary bar sedimentary facies zones are formed in Huanghua, Wen 'an, Baoding, Jinan and Laiwu.

Taiyuan Formation is composed of gray-black mudstone, gray bioclastic limestone, timely sandstone and coal seam, rich in plant fossils, 26.9~252 meters thick, and continuously deposited with the underlying benxi formation. Taiyuan Formation is the main coal-bearing stratum in the basin, which is widely distributed in the whole basin. It starts from Beijing and Shijiazhuang in the north and ends in Jinan and Xuzhou in the east, with a thickness of 140 ~ 200m, and becomes thinner to the southwest. Coal seams are distributed in the north of the 37 north latitude line, with a thickness of 15 ~ 35 m, with a maximum thickness of 45 m, which is generally 5 ~ 10 m in other areas. There are 7 coal-bearing layers in Tangshan in the north, with a thickness of13m; ; Dacheng coal-bearing 5 layers, 5 m thick. West Fengfeng coal-bearing 8 layers, 8.3 m thick. There are 7 coal-bearing strata in Zibo in the east, with a thickness of 6.5m. There are 8 coal-bearing strata in Yuxian in the south, with a thickness of 2.4m；: ; Weishi coal-bearing layer 6, 5.5m；; Thick; Huainan coal-bearing 1 ~ 9 layer, thickness1.9 m.

The lithofacies palaeogeography of Shanxi period is mainly characterized by the sedimentary facies of delta plain. In the late Taiyuan, the seawater retreated southward, and the lagoons in the bay retreated to Juxian, Xuzhou, Huainan and Fuyang. North of Tangshan-Shijiazhuang line is a fluvial facies area, with main rivers including Yanqing, Beijing, Chengde and Funing, flood plain distribution area and alluvial fans in Chaoyang area. The south of Tangshan-Baoding line is a delta plain distribution area, with braided branch channels developed and inter-branch marshes distributed in the south of Tangshan-Shijiazhuang. In the low-lying and humid area of the delta plain, the forest vegetation is lush, forming peat bogs, which vertically alternate with the inter-branch plain and branch canals, and are the main coal-forming facies zones. Between the north and south delta plains is a tidal flat facies area, on which is a coastal swamp, which is distributed in Huixian, Hebi, Lankao and other places.

Shanxi Formation is gray-black mudstone, sandy mudstone and silty sandstone, sandwiched with carbonaceous mudstone and coal seam, with stable lithology and rich plant fossils, with a thickness of 23 ~ 99.8 meters, which is in integral contact with the underlying Taiyuan Formation. Shanxi Formation is also the main coal-bearing stratum, which is widely distributed in the basin. Bounded by Beijing, Shijiazhuang, Kaifeng and Huainan, it is 60 ~ 80 m thick in the east and thinner in the west. Coal seams are widely distributed, but the thickness varies greatly. Coal seams are distributed in the east and south of Taihang Mountain. Generally, when sandstone is developed at the bottom, the coal seam is thicker. The coal seams in Tangshan, Huanghua, Linqing, Zhengzhou, Pingdingshan and Huaiyang are 79 m thick, with a maximum of 13 m and 3 ~ 5 m in other areas. Tangshan in the north contains 6 layers of coal, 6.5m；; Dacheng has two coal-bearing strata with a thickness of1m. There are 4 coal-bearing layers in the west of Fengfeng, with a thickness of 7.8m. There are 3 coal-bearing strata in the east of Zibo, with a thickness of 5.0m There are 8 coal-bearing strata in the south of Yuxian, with a thickness of 4 ~ 7m；. Weishi coal-bearing second floor, 9m; Thick; Huainan coal-bearing layer 2 is 5. 1 m thick.

The lithofacies palaeogeography of Lower Shihezi Stage is dominated by fluvial facies and delta plain facies. The northern part of Anyang-Taian line (36 north latitude) is dominated by river facies, and the southern part is dominated by delta plain facies. The main rivers south of Anyang and Taian lines are Sanmenxia-Mianchi, Yixian-Fengfeng, Quyang-Nangong-Taian, Beijing-Huanghua-Weifang, Pingquan-Liujiang and Nanpiao-Jinxi. The river flows from the northwest to the southeast, with broad floodplain deposits, lush vegetation in low-lying and humid areas and sporadic flood swamp facies zones. Alluvial fan deposits are developed in Chaoyang and Nanpiao on the southern margin of the northern ancient land. In the delta plain sedimentary facies area south of Anyang-Taian line, braided distributary channels crisscross Hebi, Dongming, Laiwu, Xiayi, Huainan and Queshan. There are inter-tributary plains and inter-tributary swamps deposited between tributaries, and the distributary channels, inter-tributary plains and inter-tributary swamps alternately overlap and cross each other in the longitudinal direction. Inter-branch swamp facies belts are mainly distributed in Lu Yi, Huaiyang, Suxian and Fengtai areas, and the cumulative thickness of coal seam is 6 ~ 18m.

The Xiashihezi Formation consists of yellow-green and yellow-gray mudstone, sandy mudstone with medium and fine sandstone and carbonaceous mudstone. From bottom to top, it consists of two lithologic sections, coarse to fine, with a thickness of 67 ~ 2 17 m, which is in integral contact with the underlying Shanxi Formation. In Beijing, Tianjin, Tangshan, Xingtai, Jinan, Zhengzhou and Xuzhou, the thickness of the first line is relatively large, which is 120 ~ 160m. Coal seams are mainly developed in Xuzhou-Zhengzhou (south of 34 30 ′ north latitude), with a thickness of 4 ~ 19 m, and the thickness increases from north to south. There is generally no coal seam in the north, but there are thin coal seams in parts of Shenxian, Beijing, Huimin, Wen 'an and Tangshan, with a thickness of 1 ~ 2 m ... Tangshan has 5 coal-bearing layers and a thickness of1.34m; ; Dacheng coal 1 layer, 0.5m thick; Yuxian coal-bearing line 4; Weishi coal-bearing second floor, 0.63 m; Thick; The area from Huaiyang to Lu Yi is 8 ~ 12 m thick, and the maximum thickness is16 m; ; Huainan coal-bearing 10 layer, thickness 19.2 meters.

The lithofacies palaeogeography of the Upper Shihezi period is similar to that of the Lower Shihezi period, with river facies and delta plain facies as the main facies. Sediments from lagoons and tidal flats in the bay have disappeared. The northern part of Zhengzhou-Xuzhou line is river deposit and the southern part is delta plain deposit. The rivers north of Zhengzhou-Xuzhou line flow from northwest to southeast, including Chaoyang, Jinxi, Chengde, Tangshan, Beijing, Zibo, Linqing and Xuzhou. Floodplain is distributed between rivers, and flood swamp deposits are rarely distributed. The south of Zhengzhou-Xuzhou line is a delta plain facies distribution area, braided tributary channels flow from northwest to southeast, tributary plains and inter-tributary swamps are distributed between tributary channels, and Pingdingshan-Huainan area is an inter-tributary swamp distribution area, mostly flaky, and the coal seam is 7 ~ 20 m thick.

The Upper Shihezi Formation is brownish red and yellowish green mudstone, light brown and grayish yellow medium-fine sandstone, with a thickness of130 ~ 625m, which is in integral contact with the Lower Shihezi Formation. Wide distribution, large thickness, lithology with the characteristics of fine top and thick bottom. Shijiazhuang, Zhengzhou, Xuzhou and Jinan are relatively thick, ranging from 400 m to 500 m. Mudstone in southern Handan and Zaozhuang is relatively developed, with a thickness of150 ~ 400 m. There is no coal seam in northern and central parts, mainly distributed in Pingdingshan and Huainan, with a thickness of 5 ~18.6 m. There are 24 layers of coal in southern Yuxian, with a thickness of 7. ; Weishi coal-bearing stratum11.7m; Thick; The coal-bearing strata in Huainan are 1 1 and the thickness is18.6 m.

The lithofacies palaeogeography of Shiqianfeng period was dominated by inland lake and river facies deposits, and the delta deposits basically withdrew. Shallow lake subfacies are distributed in Linqing, Handan, Dongming and Xuzhou, and mudstone and marl are developed, accounting for 10% ~ 16% of the total area. The shallow lakes located in the southwest corner of this area are developed with underwater alluvial fans, alluvial bodies alternately superimposed and sandstone layers developed, with a thickness of140 ~ 200m. Rivers dominate the central and northern parts. The main rivers are Pingquan, Tangshan, Dacheng and Yishui, and there are broad floodplains between the rivers.

Shiqianfeng Formation is a non-coal measures stratum and a good regional caprock, which is distributed in the whole basin. The lithology is brownish red and purplish brown mudstone, light brown and brownish gray medium-long sandstone, with grayish green mudstone, medium-thin marl and mudstone in the middle and upper part, with a thickness of 70 ~ 387 m, which is in integral contact with the underlying Upper Shihezi Formation and the overlying Lower Triassic Liujiagou Formation. The thickness south of Anyang-Zaozhuang line is relatively large, ranging from 250 to 300 m.

Carboniferous-Permian coal-bearing basins in North China mainly contain coal-bearing measures such as Taiyuan Formation, Shanxi Formation, Xiashihezi Formation and Shangshihe Formation. The maceral of coal and rock is mainly vitrinite, followed by inertinite, and the content of crust is less. The coal and rock are mainly micro-mirror inert coal, followed by micro-mirror coal and dark bright coal.

The areas where the vitrinite content of Taiyuan Formation is more than 95% are Jiyuan, Zhengzhou and Lu Yi, while the inertinite content is less than 5%, and the crust content is low. The vitrinite content is 80% ~ 95%, and the inertinite content is 5% ~ 20%, which are distributed in Handan, Xuzhou, Huainan and Pingdingshan. The vitrinite content in Xinwen and Xingtai areas is 80% ~ 95%, and the inertinite content is 20% ~ 10%, with a trace of chitin. The vitrinite in Tangshan area is 50% ~ 80%, and the inertinite group is 50% ~ 20%. In some areas, the crustacean content is above 5%, such as Tianjin 5% and Nanpiao 7.5%. The total content of vitrinite and inertinite is more than 95%, the content of chitin is less than 5%, and the content of inertinite is more than 50%. For example, the content of inertinite in Xishan, Beijing is 63.5%, and the highest is 80.5%.

The vitrinite content of Jiyuan and Zhengzhou Shanxi Formation is more than 95%, up to 99.5%, and the inertinite content is less than 5%, without crust formation. The vitrinite content is 80% ~ 95%, the inertinite content is 5% ~ 20%, and the trace chitin content is distributed from Shijiazhuang to Pingdingshan. Vitrinite accounts for 50% ~ 80%, inertinite accounts for 50% ~ 20%, and chitin accounts for 2% ~ 4%, which are distributed in the east-west zone of Tangshan. The content of vitrinite and inertinite is more than 95%, and the content of inertinite is more than 50%, such as 65.5% of Jingxi inertinite. The contents of vitrinite in Huainan, Xuzhou and Jining are 50% ~ 70%, inertinite 20% ~ 40% and chitin 5% ~ 10%.

The vitrinite content of Xiashihezi Formation and Shangshihe Formation in Jiyuan and Zhengzhou is 80% ~ 95%, and the inertinite content is 10% ~ 20%, without shell formation. The vitrinite content in Pingdingshan, Huainan and Xuzhou is 50% ~ 80%, inertinite is 10% ~ 30%, and chitin is 8% ~ 12%.

After the formation of the Carboniferous-Permian coal-bearing basin in North China in the Variscan period, it experienced post-Indosinian sedimentary construction and structural deformation and transformation, and at the same time exposed, buried deeply and thermally evolved under the influence of magmatism, causing thermal metamorphism (coalification, alkylation) or destruction of coal strata. Through the study of sedimentary history, tectonic history and thermal evolution history, it is considered that the Carboniferous and Permian coal-bearing series in North China experienced two processes: thermal metamorphism of coal and rock and thermal metamorphism of magma. Deep metamorphism occurred from Late Carboniferous to the end of Middle Triassic or at the end of local Triassic, with a sedimentary thickness of 2000 ~ 4500 m and a duration of130 ~150ma, which is regional equilibrium metamorphism. The coal seams of Taiyuan Formation and Shanxi Formation can reach lignite rank in the Late Permian, gas and fertilizer rank in the Middle Triassic, and some of them are long flame rank. In the late Indosinian period, the difference rose and fell, and the gas-fertilizer coal rank remained in the missing area of Upper Triassic, and the coal rank further rose in the falling area. When the overburden reaches 3500~4500 m and the paleogeothermal temperature is 130 ~ 150℃, lean coal is formed. At the end of Triassic, Tongxu, Jincheng and Yangquan formed an arc-shaped metamorphic belt of coke and lean coal bending to the southwest, reaching the rank of lean coal locally. Mud hills are located in the east and north, Xuzhou, Handan and Baoding are all gas-fat coal, and Wen 'an area is long-flame coal. From the Middle Jurassic to the Early Cretaceous, the tectonic changes were frequent and intense, and only some areas accepted Jurassic and Cretaceous sediments with different thicknesses. Most areas are in the uplift and denudation period of 100 Ma, and the deep metamorphism is limited to Mesozoic fault depression. Due to the superposition of deep structure and magmatism, the metamorphic degree of most strata has deepened. Most of them are annular, banded or banded, and the metamorphic zone of coal and rock is narrow, and the gradient of coal quality changes greatly, and even natural coke appears. By the end of Cretaceous, the arc-shaped lean coking coal belt formed in the northwest of Tongxu has been thermally deteriorated into lean coal and anthracite, and its scope has also been expanded. Others, such as Zhanhua, Cangxian, Dezhou, Liaocheng and Qiuxian, entered the ranks of coke and lean coal due to the superposition of Jurassic and Cretaceous. In Handan, Xuzhou, Luxi, Jingxi and other places, under the influence of magma, there are annular or banded metamorphic belts. During the Himalayan period, the Carboniferous-Permian basin in North China completely subsided again, and the Carboniferous-Permian coal-bearing measures were deeply metamorphic, and the coal seams that had become rocks and coal once again evolved from low metamorphic coal rank to high metamorphic coal rank. With the increase of coalification degree, the ability of pyrolysis of hydrocarbon gas is also improved, and the structure of coal is also changed. It is estimated that the Ro of coal and rock is 0.6% ~ 1.2%, and the buried depth of coal seam is more than 3,000 ~ 3,500m in Wuqing, Huanghua, Zhanhua, Dongying, Linqing, Dongming, Huangkou, Yanji, Niqiuji and Gu 'an, with an area of 2.6× 104 km2. Through statistical analysis, Tongxu, Jiaozuo, Jincheng and Yangquan are highly metamorphic zones dominated by anthracite, and the Ro is 2.0% ~ 3.0%, up to 6.3%. Coking coal, fat coal and gas coal change in turn in the west and south, and the east and north are wide and slow gas and fat coal areas. The Cenozoic fault depression overlapping areas such as Huanghua, Wuqing, Dongying, Linqing, Dongming and Huangkou form a semicircular gradient change zone with the same fault distribution. Huaibei, Xuzhou, Jingxi, western Henan and the east of Taihang Mountain are subjected to magmatic thermal metamorphism, with small metamorphic belt and high metamorphic degree, and natural coke can appear locally. Generally, it is annular and banded with magma, and the surrounding metamorphic degree also drops sharply.

There are three sets of regional caprocks in Carboniferous-Permian coal-bearing basins in North China. Carboniferous and Permian mudstones are developed in the whole basin, with a thickness of 300~800 m and a maximum thickness of 930 m. Due to the later basin decomposition, the remaining thickness of each fault block is different. The caprock covered in the late period is mainly argillaceous rock with a thickness of 1000 m under Tertiary, with gypsum and salt layers locally developed, which are widely distributed and thick. The thickness of mudstone in Jizhong and Huanghua fault depressions is1000 ~ 4,000m, that in Linqing and Dongming fault depressions is 500 ~ 2,500m, that in Jiyuan and Huangkou fault depressions is 500 ~ 2,400m, and that in South North China Basin is 500 ~/kloc-0,000m. In addition, the variegated mudstone in the upper part of Xiashihezi Formation is 10 ~ 30 m thick, and the purple argillaceous rock in Shiqianfeng Formation is 50 ~ 200 m thick, all of which can be used as regional caprocks.

Refer to Atlas of China Coalbed Methane Basin, Map of Exploration Degree of Coalbed Methane in North China Basin, Lithofacies Palaeogeography Map of Benxi Stage of Late Carboniferous in North China Basin, Lithofacies Palaeogeography Map of Taiyuan Stage of Late Carboniferous in North China Basin, Lithofacies Palaeogeography Map of Shanxi Stage of Early Permian in North China Basin, Lithofacies Palaeogeography Map of Shihezi Stage of Permian in North China Basin, Carboniferous and Permian Residual Thickness Map of North China Basin and North China Benxi formation Coal Seam Thickness Map of Upper Carboniferous in North China Basin, Taiyuan Formation of Upper Carboniferous in North China Basin, Shanxi Formation of Lower Permian in North China Basin, Shanxi Formation of Lower Permian in North China Basin, Lower Shihezi Formation of Lower Permian in North China Basin, Lower Shihezi Formation of Lower Permian in North China Basin, Coal Seam Thickness Map of Upper Permian Upper Shihezi Formation in North China Basin, and Schematic Diagram of Coal-rich Belt Migration in Carboniferous and Permian Coal-bearing Basin in North China (prototype).