25 Mesozoic coal-bearing basins in Junggar-Xing 'an active belt and Tianshan-Chifeng active belt.

The tectonic evolution history of Junggar-Xing 'an active belt in the southern margin of Siberia plate and Tianshan-Chifeng active belt in the northern margin of Tarim-North China plate is a history of the occurrence and development of ancient Asian oceans and the formation and development of ancient Asian continents. The formation of continental basement has experienced three stages: continental core-primitive ancient land-continental cratonization. In the formation and evolution stage of continental basement in the late Neoarchean, the metamorphic rock series of Mashan Group in Jiamusi Block experienced a strong change after Wutai Movement, and the ancient continental core was further solidified. In Proterozoic, the original ancient land was consolidated and expanded around Jiamusi and other land cores, which laid the foundation for the final formation of Tarim and North China ancient land. There are three aulacogen in Jiamusi massif in Mesoproterozoic, namely Mudanjiang, Yilan and Taipingling, and clastic-carbonate mixed volcanic rocks are formed in Daxinganling, Xilinhot, Beishan, Yili and Middle Tianshan. Jinning movement expanded and solidified the original ancient land, forming the ancient land blocks of North China and Tarim, which are much larger than today. The ancient Asian ocean was in the stage of continental margin accretion and evolution, and the continent began to disperse from Sinian to early and middle Ordovician. Since Phanerozoic, marginal rift systems have appeared in Tarim and North China. Due to the expansion of the seabed, Altai, Junggar, Yili, Middle Tianshan, Xilinhot, Nensong and Jiamusi, which originally belonged to Tarim and North China, separated from Tarim and North China and drifted northward, forming a large piece of land with different sizes in the ancient Asian ocean between Siberia and Tarim. Since Ordovician, the continental margin has gradually merged in the form of terrane through the contraction of ocean crust and the proliferation of mainland. It has gone through several stages: continental dispersion, plate activity and ocean recession. In the late Variscan period, from the Middle Carboniferous to the Early Permian, the north and south continents gradually collided from west to east on the northern line of hubbell Ga-Xilamulun in Ilya, completing the docking of Siberia and Tarim-North China, forming a unified northern Asian continent.

The ancient Asian continent experienced the complex process of basement formation and continental margin accretion and evolution, and the compressional and extensional environments appeared alternately, which led to the linear structure development of Junggar-Xing 'an active belt and Tianshan-Chifeng active belt, strong magmatic activity and complex metamorphism, and became the main folded orogenic belt between the two continents. Sandwiched between the north and south continents, micro-landmasses and linear folded orogenic belts in different periods interweave with each other, forming a series of mountain systems and great basin in northern Asia. Chinese mainland is in an arc structure around Siberia, with northwest in the west, northeast in the east and south in the middle. Located in the Junggar-Xing 'an active belt of the North Siberian plate, From north to south, there are Altai-Ergon Caledonian fold belt and Erqis-Xiguituqi Hualixi fold belt, Junggar micro-landmass (including Paleozoic continental margin accretion fold belt of West Junggar, junggar block, Bogda-Halike middle and late Hualixi continental margin accretion fold belt) and Xilinhot micro-landmass (including late Hualixi continental margin accretion fold belt of Xiwuzhumuqin Banner, Xilinhot landmass and Zhesibao-Wulan). Tianshan-Chifeng active belt located in the south of Tarim-North China plate, from north to south, is the Paleozoic continental margin accretion fold belt of Ilya Habega-Jueluotag, the Ili-Issyk Kul micro-block (including Ili block and Jelke Paleozoic continental margin accretion fold belt), the Middle Tianshan block, the Beishan rift belt, and the Wenduer Temple-Xilamulun Paleozoic continental margin accretion fold belt. These structural units are generally divided into super-lithospheric faults or lithospheric faults, and some faults are developed for a long time, which control the evolution of structural framework. The main faults in this area are Erqis-Delbays dry lithosphere fault, Karamay-Erlian lithosphere fault, Dunhua-Mishan lithosphere fault and Yilan-Lan Shu lithosphere fault, among which the Habega-Xilamulun lithosphere fault in Yilan is the suture line between Siberia plate and Tarim-North China plate.

The stage of Tethys activity along the Pacific coast is characterized by continental margin activity and intracontinental block ups and downs. After the Variscan period, due to the subduction of the Pacific plate to the west, the Indian plate and the Siberian plate were pressed north and south, and the tectonic activity in the west was dominated by block ups and downs, while the eastern part was involved in the active zone of the Pacific continental margin, with strong tectonic magmatism. Foreland depression zone, continental tectonic-magmatic "activation" zone and continental marginal active zone were formed in the NE-NE sunny zone, superimposed on the continental accretion zone of ancient Asia.

After the unification of the North Asian continent at the end of the Early Permian, the late Permian-Triassic was the filling period, and the mountainous area suffered from strong erosion, and the basin quickly accepted molasses and lacustrine debris accumulation. The Indosinian movement in the east is very strong, pushing the late Triassic-early Jurassic oceanic crust section of the Xihaote fold belt in the east to Wandashan. The Dunhua-Mishan fault moved to the left greatly, and intermediate-acid volcanic rocks erupted and granite emplaced. There were sporadic lacustrine sandstone and mudstone deposits in the early and middle Triassic, and there were still sporadic lacustrine sandstone and mudstone deposits in the late Triassic. Jiutai Dajianggang Formation in central Hebei Province is a continental coal-bearing clastic rock deposit, and Hunjiang has marginal sea coal-bearing clastic rocks and land-sea coal-bearing clastic rocks mixed with calcareous clastic rocks. From Jurassic to the middle and late Early Cretaceous, the eruption of intermediate-acid volcanic rocks was accompanied by granite emplacement, large faults and deep faults, forming a series of fault basins, and some of them further evolved into large depression basins. Jurassic and Cretaceous fault basins are all over Northeast Asia, and the larger basins are Songliao Basin, Sanjiang Basin Group, Hailaer Basin Group and Erlian Basin Group in the east of Chinese mainland. The western part of the continent is pushed northward by the Indian plate and southward by the Siberian plate, showing the ups and downs of fault blocks, forming a NW-trending intracontinental rift basin. In the early Middle Triassic, fluvial and lacustrine facies sandstone and mudstone were deposited, in the late Triassic, fluvial and lacustrine facies coal-bearing sandstone and mudstone were deposited, in the early Middle Jurassic, fluvial and lacustrine facies variegated clastic rocks were deposited, and in the late Jurassic and Cretaceous, coal-free clastic rocks were deposited. Mesozoic basins have good inheritance, and the coal accumulation period is from late Triassic to early Cretaceous. The larger basins are Junggar basin, Yili basin, Turpan-Hami basin and Badain Jilin basin.

At the end of Variscan, after the Siberian old land and Tarim-North China old land merged, the Junggar-Xing 'an active belt and Tianshan-Chifeng active belt, which were at the front of the two old lands, folded back and were in a state of uplift and denudation in Indosinian. In Triassic, only Junggar, Turpan-Hami, Yili in the west and Jidong in the east formed rift basins, which deposited sand and mudstone of inland rivers, among which Jidong had coal-bearing measures. Jidong basin group at the eastern end of Tianshan-Chifeng active belt includes Shuangyang, Jiaohe, Yanji, Hunchun and Dongning basins, which are covered by Permian strata. The prototype coal-bearing basin may be large or even complete, and the residual basins (slices) transformed in the later stage are everywhere. Hunjiang basin in Liaodong uplift is covered on Yuanguyu metamorphic basement, which is a coal-bearing deposit with alternating marine facies.

Jurassic coal-bearing basins are distributed in Junggar-Xing 'an active belt, including Junggar basin, Heshun Tuoluogai basin, Turpan-Hami basin, Santanghu basin and Tianshuijing basin. Yining basin, Yurdus basin, Yanqi basin, Kumish basin and Beishan basin group are distributed in Tianshan-Chifeng active belt. Among them, Junggar, Turpan-Hami and Santanghu basins located in the northern part of Tianshan fold belt were napped by fold belt to form foreland depression basins, and Yurdusi, Yanqi and Kumish basins formed extensional strike-slip fault basins parallel to mountains. Tianjing and Beishan basins located on both sides of Altun fault zone have strike-slip compression or pull-apart fault depression properties. The coal-bearing series is Shuixigou Group, including Badaowan Formation in the lower part of Lower Jurassic and Xishanyao Formation in the lower part of Middle Jurassic, and the non-coal-bearing strata of Sangonghe Formation between the two coal-bearing series. Badaowan Formation is a coal-bearing deposit of fluvial and lacustrine facies, which is composed of conglomerate, sandstone, glutenite, siltstone and mudstone sandwiched with coal seams.

Junggar basin has a large area, developed sedimentary facies and developed coal seams. The coal-bearing strata are Badaowan Formation and Xishanyao Formation, and the exposed strata around the basin are inconsistent. Located in the southeast of Turpan-Hami basin, the coal-bearing series of Badaowan Formation is missing in the southern margin and developed in the northern margin, with conglomerate, sandstone, mudstone and carbonaceous mudstone sandwiched with coal seams. The lithology of the basin edge is coarse, and it becomes thinner towards the basin, with a thickness of 270~400 m, 540 m in the west and 4 14 m in the east. The Aiweiergou area in the west has the best coal bearing, reaching 18 layer, with a thickness of 32.2 m, generally 5 ~ 9 layers and a thickness of 9.8 ~15.4 m. Xishanyao Formation is composed of conglomerate, siltstone, mudstone and carbonaceous mudstone sandwiched with coal seams. The deep part is dominated by fine clastic rocks, which gradually taper from north to south. The eastern part is the thickest 156 1 m, with an average thickness of 384 ~1000 m. The southern part of the basin is getting better and better, with 26 ~ 63 coal layers and a coal seam thickness of 34.03 ~ 6000 m.

The coal-bearing measures in Santanghu Basin, Shuntuoluogai and Shuixigou Group are basically the same as those in Junggar Basin. The marginal thickness of the Huoshuoluogai basin is small, which is coarse clastic rock with poor coal-bearing property, and the belly of the basin is thick, mainly fine clastic rock with good coal-bearing property. Badaowan Formation is 372~747 m thick, 6 ~ 26 coal-bearing layers, 4.0~48.3 m thick, and 3 ~ 20 layers can be mined, with a thickness of13.70 ~ 35.70 m. Xishanyao Formation is 484 ~ 1083m thick and coal-bearing/kloc-0. It can mine 6 ~ 2 1 layer, with a thickness of 7.7 ~ 34.2m ... Santanghu basin is coarse clastic rock with poor coal-bearing property in the northeast, and thick clastic rock with good coal-bearing property in the southwest. Badaowan Formation is 300 ~ 1000 m thick, contains coal 1 ~ 2 1 layer, is 2.0~50.0 m thick, and can mine 2 ~ 14 layer, with a thickness of 3.7 ~ 46.7 m. Xishanyao Formation is 60 ~/thick. Shuixigou Group in Yining Basin, the lower part is interbedded with conglomerate, sandstone and mudstone, sandwiched with carbonaceous mudstone and coal seam, with a thickness of105 ~ 890 m; The upper part is sandstone, conglomerate, mudstone sandwiched with carbonaceous shale and coal seam, with a thickness of100 ~ 300m. The northern margin of the basin contains the best coal, 14 ~ 36 layers, with a thickness of 54.9 ~ 1 16.3 m, generally 2 ~ 3 layers and a thickness of 2.4 ~ 84 m. Shuixigou Formation in Yurdusi Basin is composed of conglomerate, sandstone mixed with siltstone, mudstone and coal seam, with a thickness of 457~563 m, 2 ~ 3 coal-bearing layers and a thickness of 2.6 ~ 8.4 m. ..

Located in the Yanqi Basin and Kumish Basin in the Tianshan-Chifeng active zone, the Jurassic coal-bearing system is consistent with the Tarim Basin, belonging to the crassus Group of Middle and Lower Jurassic. The Lower Hamangou Formation is composed of coarse sandstone, glutenite mixed with siltstone, mudstone and coal seam, with a thickness of 120 ~ 350 m and coal content of 3 ~ 165438. Tashidian Formation in the lower part of Middle-Upper Jurassic is a coal-bearing stratum, with sandstone, siltstone and mudstone mixed with glutenite, carbonaceous shale and coal seam, with a thickness of 520m and 9-66 layers of coal and a thickness of 64.8m.. ..

The middle and lower Jurassic coal-bearing measures developed in the Dongshuijing basin in the east of Turpan-Hami basin, Santanghu basin and Beishan basin group (Gongpoquan basin and Wutonggou basin) in Tianshan-Chifeng active zone belong to Oyamaguchi group. Oyamaguchi Group was formerly known as Longfeng Mountain Group, also known as Shapor Group. The lower part of the lower series is missing, and the upper part is Jijigou Formation, the lower part of Shapoquan Formation and the upper part of Qingtujing Formation. Its lithology is coal in the lower part, dark mudstone in the middle part and variegated sandstone mudstone in the upper part, with a thickness greater than 1500 m, which is unconformity contact with the underlying Permian. Above it is Shazaohe Formation, which is unconformity contact with Chijinbao Formation and Xinminbao Formation of Lower Cretaceous.

It is distributed in Dongwuzhumuqin Basin, Holingol Basin and Xilinhot Basin to the north of Xilinhot Block in the east of Junggar-Xing 'an active belt. The absence of coal-bearing measures in the lower part of Lower Jurassic, the upper part of Lower Jurassic and Middle Jurassic are all called alatan Heli Group. The lower part is composed of glutenite, sandstone and mudstone, with a thickness of 250~420 m and no coal. The upper part is mudstone, claystone and fine sandstone sandwiched with coal seams, with a thickness of 260-350m, of which 6-25 minable seams are thick10.7-40m ... There are 4 coal groups in the lower part of Xiwuqi area, with a thickness of 20.7 m, coarse lithology and no coal in the upper part. The Songliao Basin Group in the west of Songliao Basin includes Suolun Basin, Wulanhaote Basin, Zhalute Basin and Linxi Basin. The coal-bearing series is the lower Jurassic Hongqi Formation, which is in unconformity contact with the underlying Permian and the overlying Wanbao Formation, and the coal-bearing seam of Wanbaobao Formation is the lower part of Middle Jurassic. Hongqi Formation is a continental coal-bearing clastic rock deposit, with conglomerate, sandstone, intermediate-acid tuffaceous sandstone, medium-fine sandstone and siltstone interbedded with coal seam in the lower part and siltstone and mudstone interbedded with sandstone and thin coal seam in the upper part. It is distributed in Wanbao, Linxi and Zalute States, with the thickness of Tata Yingzi 100 m in the north and Taipingchuan's thickness of 780 m in the south, with the maximum thickness of 1.300m, 22 coal-bearing layers, coal mining 15 layers and single layer thickness of1~ 65438+. Wanbao Formation is coal-bearing clastic rock, mixed with intermediate-acid volcanic rocks and pyroclastic rocks, with poor coal-bearing property. The northern part of Songliao basin group includes Tahe, Huma, Heihe and Dayangshu basins. Jiufengshan Formation in the middle of Upper Jurassic coal-bearing system is coal-bearing pyroclastic rock and clastic rock mixed with basalt, with a thickness of 43 ~ 400 m ... distributed in Huma-Heihe-Nenjiang area. There are 22 layers of coal in Huola basin, and 4 layers can be mined, with a single layer thickness of 0.14 ~ 22.99 m; Heibaoshan and Muerqi contain coal 15 layers, and 8 layers can be mined, with a single layer thickness of 0.18 ~13.12m; Poplar contains 5 layers of coal, 2 layers can be mined, and the thickness of single layer is 0.9 ~ 2.4 m.

Songliao basin is located in the east of Junggar-Xing 'an active belt and Tianshan-Chifeng active belt, spanning two tectonic units. Its main body is located in Nensong block, which is covered by Quaternary sediments. The overlying strata are mainly the Late Cretaceous-Tertiary depression caprock deposits, and the lower strata are the Late Jurassic-Early Cretaceous coal-bearing measures. The caprock is the pre-Sinian metamorphic basement and the scattered Paleozoic and Triassic. Through drilling and geophysical exploration, four fault basin groups composed of NE-trending concealed belts were identified, including Nenjiang-Yi 'an-Qiqihar-Tailai-Taonan-Kailubei concealed belt, Baiquan-Laohugang-Daqing-Datong-Daan-Tongliao-Naiman concealed belt, Cyclobalanopsis-Zhaozhou-Songyuan-Gan 'an-Changling concealed belt and Yichun-Changling concealed belt. The coal-bearing strata in Jurassic and Cretaceous fault basins are Baicheng Formation of Middle Jurassic, Huoshiling Formation of Upper Jurassic, Shahezi Formation and Yingcheng Formation of Lower Cretaceous. Baicheng Formation consists of conglomerate, sandstone, siltstone and mudstone mixed with tuff and thin coal. Huoshiling Formation consists of volcanic rocks, pyroclastic rocks and coal-bed clastic rocks. The Jurassic fault basin in the western fault zone lacks the overlying strata of the Lower Cretaceous.

Sanjiang basin group is located in Jiamusi block in Junggar-Xing 'an active zone, which is a Yanshanian coal-bearing basin developed on Precambrian metamorphic basement. The faulted basin was formed in the late Jurassic, expanded in the early Early Cretaceous and began to shrink in the middle of the Early Cretaceous. After menstruation, the basin transformed into several small sedimentary tectonic basins. Jurassic residual basins mainly include Hulin, Mishan and Jixi basins. The exposed stratum is Peide Formation of Middle Jurassic, which is continental conglomerate, sandstone, coal seam and pyroclastic rock. Didao Formation of Upper Jurassic is composed of medium coarse sandstone, fine sandstone, conglomerate, tuffaceous sandstone and carbonaceous shale sandwiched with thin coal seams, with a thickness of 0 ~ 630 m ... The middle and upper Jurassic in Hulin area are all called Longzhaogou Group, including Middle Peide Formation and Upper Yunshan Formation. It is composed of sandstone, siltstone and mudstone intercalated with coal seams, and locally intercalated with rhyolitic breccia. Yunshan and other places contain 7 ~ 22 layers of coal, and 3 ~ 4 layers can be mined, with a thickness of 6.77 m and a single layer thickness of 0.2~3.55 m, mainly thin coal seams.

Jizhong basin group is located in the east of Tianshan-Chifeng active belt and Songliao basin, including Shuangyang basin, Liaoyuan basin and Huadian basin. The basement of Shuangyang Basin is Carboniferous and Permian sedimentary rocks and Variscan granite, on which there are coal-bearing strata of Dajianggang Formation in Late Triassic. Nine groups of Upper Jurassic coal-bearing series are lacustrine coal-bearing clastic rocks, sandstone and mudstone mixed with volcanic rocks and coal seams, with a thickness of 50 ~ 350 m and 2 ~ 4 coal-bearing layers, with exploitable 1 ~ 2 layers and a thin coal seam of 0.8 ~1.0 m. ..

The distribution characteristics of Cretaceous coal-bearing basins in Chinese mainland are different not only from Paleozoic craton coal-bearing basins, but also from Triassic and Jurassic coal-bearing basins. Cretaceous coal-bearing basins are mainly distributed in Junggar-Xing 'an active belt and East Tianshan-Chifeng active belt in the northeast of the mainland and the northern margin of North China block, and only sporadically distributed in Gangdise-Tengchong active belt of Tibet-Yunnan plate. Cretaceous coal-bearing basins are concentrated in the early Cretaceous, mainly NE-NNE fault basins, and some of them overlap with late Jurassic fault basins or late Cretaceous non-coal-bearing sedimentary caprocks. Except Sanjiang basin group adjacent to Wandashan plate and Cretaceous basin of Tibet-Yunnan plate, the rest are continental deposits, and some basins contain volcanic rocks or pyroclastic rocks in coal-bearing measures.

Hailaer basin group is located in the eastern part of Altai-Irtysh Paleozoic continental margin accretion fold belt, and the northern part of Irtysh-Delbays dry fault belt is a Yanshanian sedimentary basin developed on the basement of Paleozoic fold belt. Coal-bearing basins are distributed in northeast direction, including Manzhouli, Hulun Lake, Krulun Lake Basin, Ergon (left) Basin, Northern Hailar Basin, Ligedong-Beierhu Concealed Zone in new castle, Hailar and yakeshi. The lower part of the basin is the Upper Jurassic Xing 'anling Group, which is unconformity with the underlying Permian and pseudo-conformity with the overlying coal-bearing strata. Coal-bearing rock series belongs to Zhalainuoer Group of Lower Cretaceous, which is divided into upper and lower groups. It lacks upper Cretaceous strata and is covered by Cenozoic sediments. Damoguaihe Formation in the lower part of coal-bearing strata is deposited by continental coal-bearing clastic rocks, with a thickness of 220 ~ 10~90 m, 5 ~ 20 coal-bearing layers, a thickness of/kloc-0 ~ 90 m and a single layer thickness of 2 ~10 m. The main coal seam is located in the middle of coal-bearing section, with a thickness of 4 ~ 30 m. It is divided into three sections from bottom to top. The glutenite section is mainly distributed at the edge of the basin and consists of conglomerate, glutenite mixed with siltstone, mudstone and thin coal seam with a thickness of 20 ~150m. Silty mudstone section is mudstone, siltstone mixed with fine sandstone and coal seam, with a thickness of100 ~ 500m; Mudstone section is mudstone, siltstone, silty mudstone mixed with thin medium-fine sandstone, siltstone and local coal seam, with a thickness of 100 ~ 400 meters ... Zhalainuoer, Yimin, Dayan, Xihulitu and Baorixile have better coal content. The upper Yimin Formation of coal-bearing series is composed of mudstone, siltstone, sandstone and glutenite, with a thickness of 300 ~ 500m, containing 3 ~ 4 coal groups, each with 1 ~ 5 layers, with a thickness of10 ~/8m, and the lower main coal seam is 10 ~ 500. Zhalainuoer, Yimin, Dayan, Huhonuoer and Honghuaerji have better coal content.

Erenhot basin group includes Honggeer basin, East Wujimuqin-Erenhot and Helingele-Xilinhot concealed belt, Helingele, Bayanhua and Xilinhot basins, Daleinor-Su Nite and Su Nite-Wulijitu concealed belt, northern Wuchuan and Wuchuan basins, and Lige basin in new castle. Erlian basin group is located in the east of Inner Mongolia on the border between China and Mongolia, and it is distributed in the northeast, with a wide range, mainly distributed in the east of Junggar-Xing 'an active belt, in the south of Erqis-Delbays dry fault zone, and across Tianshan-Chifeng active belt and the northern edge of North China block. There are sporadic Jurassic strata exposed under Erlian Basin Group, which are coal-bearing strata of alatan Heli Group of Middle and Lower Jurassic, and the upper Jurassic Xing 'anling Group is in unconformity contact with the overlying coal-bearing strata. Bayanhua Group and Huolinhe Group of the Lower Cretaceous are the main coal-bearing strata, lacking the upper Cretaceous strata and covered by Cenozoic sediments. Bayanhua Formation is widely distributed, consisting of glutenite, sandstone, siltstone, mudstone and coal seam, with a thickness of 500～2000m ... It is divided into five lithologic sections, the coal-bearing section is located in the middle with a thickness of 82 ~ 3 16 m, and there are 48 coal-bearing layers with a thickness of 98.80m.. There are 1 ~ 3 coal seams in the west, and 1 ~ 2 coal seams can be mined with a thickness of1.1~ 25.3 m. The coal-bearing system in Huolinhe Basin is located at the eastern end of the basin group, which is called Huolinhe Group. It belongs to the continental coal-bearing clastic rock deposit with a thickness of 1700 m and is divided into six lithologic sections. The coal-bearing conglomerate section is located at the bottom and consists of conglomerate, glutenite and sandstone with a thickness of 225 m. The lower mudstone section is mudstone and siltstone with thin sandstone, with a thickness of100 ~ 500m; The lower coal-bearing interval is sandstone, coal seam, mudstone and siltstone, with 5 groups of dozens of coal-bearing layers, with a thickness of 10 ~ 100 m and a thickness of 300 ~ 600 m; ; The upper mudstone section is siltstone and mudstone with thin oil shale, with a thickness of150 ~ 350m; The upper coal-bearing section is sandstone, siltstone and coal seam, with a thickness of 400 m and 20 thin coal layers, with a thickness of 1m, which is unstable; Sandstone and mudstone section is located at the top, which is sandstone, siltstone and mudstone with a thickness of 250 m. The coal-bearing series of Wuchuan Basin is Guyang Formation of Lower Cretaceous, with conglomerate and glutenite mixed with thin mudstone and fine sandstone at the bottom, mudstone, shale, oil shale mixed with sandstone, gypsum layer and calcareous mudstone in the middle and upper parts, and two lignite layers in the middle, which can be mined for 4-7 layers, with the maximum thickness of 5- 18m.

After Yanshanian, Hailaer Basin Group and Erenhot Basin Group were located in the continental tectonic-magmatic "activation" zone of coastal Pacific tectonic domain, belonging to Daxing 'anling-Taihang-Wulingshan uplift zone. After the early Cretaceous coal-bearing measures were deposited, the uplift zone rose regionally and the sedimentary cover was missing in the late Cretaceous. The Lower Cretaceous strata are directly covered by Cenozoic sediments, and the coal-bearing measures are not deeply buried, and the degree of coal metamorphism is low, mainly lignite. The coal-bearing strata are shallow and lack of regional coverage.

Songliao basin is located in the east of Junggar-Xing 'an active belt and Tianshan-Chifeng active belt, and the main body of the basin is located in Nensong block. During Indosinian period, the uplift of the block suffered denudation, and an intermontane depression was formed locally in the Late Triassic. In the early Yanshan period, it was a small intermontane depression, forming coal-bearing volcanic rocks and clastic rocks. After the Middle Jurassic, there was a strong tectonic change, and after the Late Jurassic, it was a basin development stage, which experienced two stages and two cycles. The first Yanshan cycle includes the early rifting period of Huoshiling in late Jurassic, the deep rifting period of Shahezi-Yingcheng in early and middle Cretaceous, the rifting transition period of Denglouku in late early Cretaceous, the main depression period of Quantou-Nenjiang in late Cretaceous and the shrinking period of Sifangtai-Mingshui Basin in late Cretaceous. The second Himalayan cycle includes the early rift period of Paleogene and the late Oligocene-Quaternary depression period. Mesozoic coal-bearing basins were mainly developed in deep rifting period and early rifting period. Cretaceous coal-bearing basin is a superimposed fault basin based on Jurassic fault basin. The coal-bearing measures are Shahezi Formation in the lower part of Lower Cretaceous and Yingcheng Formation in the middle. The southern part of the basin is called Shahai Formation and Fuxin Formation. There are good coal-bearing strata around the basin, and the buried depth in the middle of the basin is different. These two sets of coal-bearing measures have been drilled by deep oil and gas wells. Since Mesozoic, Songliao basin has been in the continental tectonic-magmatic "activation" zone in the coastal Pacific tectonic domain, and has been in a stable subsidence state since the late Yanshan period, which is a part of Songliao-North China-Jianghan subsidence zone. The caprock deposits formed in the Denglouku Formation in the late Early Cretaceous and its later depression are favorable conditions for the preservation of coal-bearing basins, which are conducive to the formation, evolution and preservation of coalbed methane.

The southern basin group of Songliao Basin, located in the uplift belt of the northern margin of North China landmass, including Fuxin Basin, Beipiao-Chaoyang Basin and Chifeng Basin, are all Cretaceous fault basins with NE-NNE distribution, and their formation age and mechanism are the same as those of Songliao deep fault basin. It is only because of the uplift and fold of the northern margin of North China block after the late Jurassic that the early Cretaceous sedimentary rocks are exposed, which is not conducive to the preservation of coal-bearing rock series. The early Cretaceous coal-bearing strata are Shahai Formation and Fuxin Formation, and the coal-bearing strata in the southern margin of Songliao Basin are also named after them. Shahai Formation is a continental coal-bearing clastic rock deposit, which is divided into three lithologic sections with a thickness of 578 ~1370 m. The lower conglomerate section is thick conglomerate, coarse sandstone mixed with fine sandstone and thin siltstone, with a thickness of 72m；. ; The middle coal-bearing section is coarse, fine and siltstone, with many thin coal seams and coal lines, and the thickness is145m; ; The upper mudstone section is mudstone, argillaceous siltstone mixed with sandstone and conglomerate, with a thickness of 371m. Fuxin basin contains 6 coal groups, with a total of 14 layers, and the coal seams are thin, except for one layer of 2 ~ 3 m, the others are all 0.8 ~1.2 m. Chifeng basin (Pingzhuang and Yuanbaoshan) is composed of conglomerate section, mudstone section and coal-bearing section, with a thickness of 1000 m. Kangping Formation consists of sandstone, glutenite mixed with mudstone, siltstone and coal seam, with a thickness of 300 ~ 670 m. Fuxin Formation is a coal-bearing coarse clastic rock deposit, which is in integral contact with Shahai Formation, with a thickness of 655 ~ 1200m. From bottom to top, it is the Gaode section, the Taiping section, the middle section, the Sunjiawan section and the Shuiquan section. The gaode section is siltstone and mudstone with gravel, with 2 ~ 3 thin coal seams in the upper part, with a thickness of 20 ~ 250 m; the other four sections are coarse gravel sandstone-sandstone siltstone interbed-coal seam-siltstone; the top water spring section contains 10 unstable thin coal, and the other three sections all contain extremely thick coal seams as the main coal-bearing sections. Each section of Fuxin basin contains coal, with the thickest thickness of 10 ~ 80 m, and most of them are coal seams larger than10 m. Pingzhuang and Yuanbaoshan in Chifeng basin have good coal-bearing properties, with three main coal seams with the thickness of 30 ~ 50 m and the maximum thickness of100 m.

North Hebei basin group is located in Tianshan-Chifeng active belt and the northern margin of North China block, including Zhangbei basin, Duolunxi basin, Guyuan basin and Weichang basin, which is a part of the whole NE-NE basin group, but the basins are scattered. Except for Duolunxi Basin, which is the same as Bayanhua Group of Erlian Basin Group, all other basins are Qingshilai Formation, with Jiufotang Formation of Upper Jurassic below and Shangjingzi Formation of Upper Cretaceous above, which belongs to coal-bearing clastic rock deposit of inland lake facies with a thickness of 242 ~ 1000 m and poor coal-bearing property. Guyuan basin has good coal-bearing property, with 34 coal-bearing layers and a thickness of 67.23 m, and the main coal seam is 0.84~57.73 m thick, with an average thickness of 22.83 m.

Sanjiang Jurassic-Cretaceous coal-bearing basin is located in Jiamusi block in the east of Junggar-Xing 'an active belt, which was formed in Yanshan period and based on ancient land block. After the late tectonic changes, its prototype basin was transformed into divided Hegang basin, Tongjiang concealed belt, Shuangyashan, Baoqingnan, Qitaihe-Mishan and Jixi basin. From early Jurassic to early Cretaceous, coal-bearing basins experienced early rifting, middle expansion and late contraction. Small faulted basins were formed in early Jurassic; The rift expanded in the Middle Jurassic, and coal-bearing clastic rocks and volcanic rocks were formed in the Peide Formation. In the middle of the late Jurassic, seawater invaded during the dripping period, forming coal-bearing deposits of marine and land-sea alternating phases. From the late Late Jurassic to the early Cretaceous, the basin expanded, and the coal-bearing clastic deposits of marine and marine facies spread and deposited in the sea area. In Chengzihe period of early Cretaceous, seawater began to shrink, forming the main coal-bearing measures in the basin. During the Muling period in the middle of Early Cretaceous, the shrinking seawater in the basin withdrew, forming continental and lacustrine coal-bearing deposits. The Cretaceous coal-bearing measures of Sanjiang Basin Group are continental coal-bearing clastic rocks of Chengzihe Formation of Lower Cretaceous, with a thickness of 500 ~1000 m ... The bottom is gravel and coarse sandstone, the middle is medium coarse sandstone, mudstone, coal seam and siltstone, and the upper is siltstone, fine sandstone and mudstone, sandwiched with coal seam and tuff. There are 20 ~ 60 coal seams, with a single layer thickness of 0.6 ~ 1.5 m and a maximum thickness of 9. 14 m, and 20 ~ 40 coal seams can be mined, with a thickness of1.07 ~ 23.13 m ... The middle of Lower Cretaceous is Muling Formation, which is integrated on Chengzihe Formation and unconformity with Shanghuashan Formation. Muling Formation is a continental lacustrine coal-bearing deposit, with fine sandstone and mudstone mixed with tuff and coal seam. The Boli and Jixi basins contain better coal, including 1 ~ 17 and 1 ~ 9, with a thickness of 3.78 ~ 7.77m. The sandstone of Zhushan Formation of Lower Cretaceous is mixed with mudstone, carbonaceous mudstone and thin coal seam, with a thickness of 930 ~ 1230m. There are 20 thin coal seams and coal lines, 2 ~ 3 layers can be mined, and 6 ~ 8 layers can be mined locally, with a thickness of 0.3~0.8 m, and the maximum thickness of a single layer is 15. 1 m ... During the Huashan period in the late Early Cretaceous, volcanic clastic rocks and coarse clastic rocks were deposited in the basin, with a thickness of 500 ~ 2000 m, and the Late Cretaceous Ilya. It is a set of variegated volcanic rocks and clastic rocks with a thickness of 200~600 m and unconformity with the underlying strata. Sanjiang basin group is located in Changbai-Zhuguang uplift belt, and it was in a state of regional uplift in the late Yanshan period. The shrinking basin, small subsidence range and thin sedimentary layer are not very beneficial to the thermal evolution and preservation of coal-bearing rock series. The strong tectonic activities in Yanshanian and post-Yanshanian are also very unfavorable to the preservation of coal-bearing rock series.

Jidong basin group is located at the eastern end of Tianshan-Chifeng active belt, including Dongning, Yanji, Wangqing, Jiaohe, Shuangyang and Liaoyuan basins. The basins are scattered and small, and they are also fault basins. Jurassic or Late Triassic coal-bearing measures exist under Cretaceous coal-bearing measures in some basins, and the preservation of fault basins is incomplete, and the superposition of upper and lower basins is imperfect. The lithology of each basin is different, and most of them are similar to the adjacent basins. Shuangyang Basin is close to Songliao Basin, and the coal-bearing strata are Yingcheng Formation of Lower Cretaceous and Chang 'an Formation below it. There are two coal-bearing layers, one with a thickness of 1 ~ 2 m and the thickest14.49 m. The coal-bearing measures in Dongning Basin belong to Naizishan Formation of Lower Cretaceous. The coal-bearing measures in Jiaohe Basin belong to Naizishan Formation, and continental coal-bearing clastic rocks are deposited. The lithology is thick at the bottom and thin at the top, with a thickness of 200~300 m and 20 layers of thin coal. The 8 ~ 12 layer is locally recoverable, with a thickness of 9.47 ~ 43 m, and the overlying Wulin formation is deposited by continental coal-bearing clastic rocks, with a thickness of 150 ~ 450 m, and the local coal-bearing mining is unstable. Chang 'an Formation, a coal-bearing series in Liaoyuan Basin, Yanji Basin and Wangqing Basin, is composed of coarse clastic rocks mixed with fine clastic rocks, with a thickness of 200~900 m, and an extremely thick coal seam with a thickness of 4 ~ 10 m and a maximum thickness of 33 m. ..

Liaodong basin group located in Liaodong uplift belt of North China block includes Fusongxi basin and Xinbin basin, in which the coal-bearing strata are Chang 'an Formation and Shahai Formation. Although the Liaodong basin group is located in the Liaodong uplift belt, they are all faulted coal-bearing basins formed in the late Yanshan period, which have the same genetic mechanism and similar geological structural characteristics as the Cretaceous basin group distributed in the northeast of Chinese mainland.