Twenty-five Mesozoic coal-bearing basins in the Junggar-Xing'an active zone and Tianshan-Chifeng active zone

The tectonic evolution history of the Junggar-Xing'an active zone on the southern edge of the Siberian plate and the Tianshan-Chifeng active zone on the northern edge of the Tarim-North China plate is a story of the occurrence and development of the ancient Asian Ocean and the formation and development of the ancient Asian continent. history. The formation of the continental basement went through three stages: continental core - primitive ancient continent - continental cratonization. During the formation and evolution stage of the continental basement in the late Neoarchean, the metamorphic rock series of the Mashan Group in the Jiamusi Massif was strongly modified by the Wutai Movement, and the ancient continental core was further solidified. In the Paleoproterozoic, the primitive ancient continent was consolidated and expanded around the Jiamusi and other continental cores, which laid the foundation for the final formation of the Tarim and North China ancient continents. During the Mid-Neoproterozoic period, three rift troughs such as Mudanjiang, Yilan, and Taipingling appeared in the Jiamusi Massif, and clastic-carbonate rocks intercalated with volcanic rocks formed in the Daxinganling, Xilinhot, Beishan, Yili, and Central Tianshan Mountains. The Jinning Movement expanded and solidified the original ancient continent, forming the North China and Tarim ancient continents that were much larger than today. During the accretionary evolution stage of the continental margin of the ancient Asian Ocean, the continents began to separate from the Sinian to the early Middle Ordovician. Marginal rift systems have appeared in the Tarim and North China ancient continents that have been consolidated since the Phanerozoic. Due to seafloor expansion, the Altai, Junggar, Ili, Zhongtianshan, Xilinhot, Nensong, Jiamusi and other microcontinental blocks that originally belonged to Tarim and the North China ancient continent have successively It separated from the Tarim and North China continents and drifted northward to form blocks of various sizes in the vast ancient Asian ocean between the Siberian ancient continent and the Tarim ancient continent. Since the Ordovician, through the subduction of oceanic crust, continents have accreted and gradually merged into the northern and southern continental margins in the form of terranes. After experiencing several development stages of continental separation, plate activity, and oceanic decay, in the late Variscan period from the Middle Carboniferous to the Early Permian, the northern and southern continents gradually collided from west to east at the Yilinhaberga-Xilamulun The northern line completes the connection between the Siberian continent and the Tarim-North China continent, forming a unified northern Asian continent.

The ancient Asian continent experienced a complex process of basement formation and continental margin accretion and evolution. Compressive and extensional environments alternated, resulting in the development of linear structures in the Junggar-Xing'an active zone and Tianshan-Chifeng active zone, and intense magmatic activity. , the metamorphism was complex, and it became the main fold orogenic belt between the two continents. Under the control of the northern and southern continents, microcontinental blocks and linear fold orogenic belts of different periods were intertwined and inlaid, forming a series of mountain systems and large basins in northern Asia. Mainland China presents an arc-shaped structural pattern surrounding the Siberian landmass, with the west trending northwest, the east trending northeast, and the central part protruding southward. It is located in the Junggar-Xing'an active belt belonging to the Siberian plate in the north. From north to south are the Altai-Ergun Caledonian fold belt and the Irtysh-Xiguitu Banner Variscan fold belt. The Junggar microcontinent (including the western Junggar Paleozoic continental margin accretionary fold belt, Junggar block, Bogdo-Khallik mid-late Variscan continental margin accretionary fold belt), Xilinhot microcontinent (including West Ujimqin Banner late Variscan continental margin accretionary fold belt, Xilinhot massif, Zhesi Aobao-Ulanhot late Variscan continental margin accretionary fold belt), Nensong-Jiamusi microcontinent (including Nensong massif, Yichun-Yanshou Caledonian fold belt, and Jiamusi massif). It is located in the Tianshan-Chifeng activity zone belonging to the Tarim-North China plate in the south. From north to south is the Yilin Haberga-Jueluotage Paleozoic continental margin accretionary fold belt, and the Ili-Issyk-Kul microcontinent (including the Ili block , Halke Paleozoic continental margin accretionary fold belt), Central Tianshan massif, Beishan rift zone, Wendurmiao-Xilamulun Paleozoic continental margin accretionary fold belt. These structural units are generally divided by superlithospheric faults or lithospheric faults. Some faults develop over a long period of time and control the evolution of the structural pattern. The main faults in the area include the Irtysh-Derbugan supralithosphere fault, the Karamaili-Eren supralithosphere fault, the Dunhua-Mishan lithospheric fault, and the Yilan-Shulan lithospheric fault, among which the Ilinha fault The Beerga-Xilamulun superlithosphere fault is the suture line between the Siberian plate and the Tarim-North China plate.

The stage of Tethys activity in the Pacific Ocean was characterized by continental margin activity and intracontinental block lifting and subsidence.

After the Variscan period, due to the westward subduction of the Pacific Plate, the north-south compression of the Indian Plate and the Siberian Plate, the tectonic activity in the west was mainly manifested as block fault lifting, while the east was involved in the Pacific continental margin active zone, and the tectonic magmatic activity was intense, forming the North Plateau. The east-northeast oceanic foreland depression zone, continental tectonic-magmatic "activation" zone and continental margin activity zone are superimposed on the ancient Asian continental accretion zone.

After the unification of the northern Asian continent at the end of the Early Permian, the Late Permian-Triassic was a period of filling and filling. The mountainous areas suffered strong erosion, and the basins rapidly received molasse-like and lacustrine clastic accumulation. . The Indosinian movement in the east was very strong, pushing the Late Triassic-Early Jurassic oceanic crust segment adjacent to the Xihot Fold Belt in the Pacific Ocean to the east to the Wanda Mountains. The Dunhua-Mishan fault shifted significantly to the left, medium-acidic volcanic rocks erupted, and granite emplaced. In the Early and Middle Triassic, there were sporadic intercontinental intermountain fluvial and lacustrine sand and mudstone deposits. In the Late Triassic, the intracontinental intermountain discontinuous fluvial and lacustrine sand and mudstone deposits are still scattered. The Dajianggang Formation in Jiutai, Jiuzhong, Jiuzhong is intracontinental coal-bearing debris. In the Hunjiang River, there are marginal sea coal-bearing clastic rocks and sea-continent alternating phase coal-bearing clastic rocks intercalated with tuffaceous clastic rocks. From the Jurassic to the middle to late Early Cretaceous, the eruption of medium-basic to medium-acidic volcanic rocks and the intrusion of granite were accompanied by the development of large faults and deep faults, forming a series of fault basins, some of which further evolved into large depression basins, such as Jurassic and Cretaceous Period rift basins are spread across the Northeast Asian continent. Larger basins include the Songliao Basin, Sanjiang Basin Group, Hailar Basin Group, and Erlian Basin Group in eastern mainland China. The western part of the continent is pushed northward by the Indian Plate and southward by the Siberian Plate, which is characterized by ups and downs of block faults, forming a northwest-trending intracontinental fault-shaped basin. In the Early and Middle Triassic, it was fluvial and lacustrine sand and mudstone deposits, and in the Late Triassic The early and middle Jurassic were fluvial and lacustrine facies sand and mudstone deposits containing coal and oil shale, the early and middle Jurassic were fluvial and lacustrine facies coal-bearing sand and mudstone deposits in intracontinental depressions, and the late Jurassic were fluvial and lacustrine facies sand and mudstone deposits without coal. The Cretaceous was a variegated clastic rock deposit of intraterrestrial fluvial and lacustrine facies. The Mesozoic basins have good inheritance, and the coal accumulation period was from the Late Triassic to the Early Cretaceous. The larger ones include the Junggar Basin, Ili Basin, Turpan-Hami Basin, and Badain Jaran Basin.

At the end of the Variscan Period, after the Siberian Ancient Continent was connected with the Tarim-North China Ancient Continent, the Junggar-Xing'an active belt and the Tianshan-Chifeng active belt at the fronts of the two ancient continents folded back and were uplifted during the Indosinian Period. In the state of erosion, during the Triassic, only Junggar, Tuha, and Yili in the west and Jidong in the east formed fault-depression basins, depositing intracontinental river and lake sand and mudstones, of which there was a coal-bearing rock series in Jidong. The Jidong basin group at the eastern end of the Tianshan-Chifeng active zone includes the Shuangyang, Jiaohe, Yanji, Hunchun and Dongning basins, covering the Permian strata. The prototype coal-bearing basin may be larger in scope or even connected into one. , the remaining basins (pieces) of later transformation are scattered everywhere. The Hunjiang basin sheet in the Liaodong uplift is capped on the Proterozoic metamorphic rock basement, and is coal-bearing sediments of marine and alternating marine and continental phases.

The Jurassic coal-bearing basins distributed in the Junggar-Xing'an active belt include the Junggar Basin, the Heshtuologai Basin, the Turpan-Hami Basin, the Santanghu Basin, and the Tianshuijing Basin. Distributed in the Tianshan-Chifeng active zone are the Yining Basin, Yurdus Basin, Yanqi Basin, Kumish Basin, and Beishan Basin Group. Among them, the Junggar, Tu-Ha, and Santanghu basins located in the northern part of the Tianshan fold belt were overthrown by the fold belts to form foreland depression basins. The Yurdus, Yanqi, and Kumish basins formed extensional and strike-slip systems with a parallel mountain trend. Fault basins, the Tianshuijing and Beishan basins located on both sides of the Altyn Tagh Fault Zone, have strike-slip compression or pull-off fault depression properties. The coal-bearing rock series is the Shuixigou Group, including the Badaowan Formation in the lower Lower Jurassic and the Xishanyao Formation in the lower Middle Jurassic, as well as the non-coal strata of the Sangonghe Formation between the two sets of coal-bearing rock series. The Badaowan Formation is fluvial and lake facies coal-bearing deposits, consisting of conglomerate, sandstone, sandy conglomerate, siltstone, and mudstone intercalated with coal seams.

The Junggar Basin is large in scope, with well-developed sedimentary lithofacies and relatively developed coal seams. The coal-bearing rock series are Badaowan Formation and Xishanyao Formation. The exposed rock strata around the basin are inconsistent. The Tuha Basin, located in its southeastern part, lacks the Badaowan Formation coal-bearing rock series on its southern edge, while its northern edge is more developed and consists of conglomerate, sandstone, mudstone, and carbonaceous mudstone intercalated with coal seams.

The lithology of the basin margin is relatively coarse, and becomes thinner toward the inside of the basin, with a thickness of 270-400 m, 540 m to the west, and 414 m to the east. The Aiweili Valley area in the west contains the best coal, with 18 layers and a thickness of 32.2 m, generally 5 ~9 layers, 9.8~15.4 m thick. The Xishanyao Formation is composed of conglomerate, siltstone, mudstone, and carbonaceous mudstone intercalated with coal seams. The deep part is dominated by fine clastic rock, which becomes thinner from north to south. The thickness is 1561 m in the east, and is generally 384 to 1000 m thick. The southern part of the basin contains coal. It has become better, with 26 to 63 coal layers and a coal seam thickness of 34.03 to 194.88 m. There are 20 to 34 minable coal layers with a thickness of 31.70 to 173.26 m. The coal content coefficient is as high as 30.

The Shuixigou Group of coal-bearing rock systems in the Heshtuologai and Santanghu basins are basically consistent with the Junggar Basin. The edge of the Heshtuologai Basin is thin and consists of coarse clastic rocks with poor coal content. The belly of the basin is thick and mainly composed of fine clastic rocks with good coal content. The Badaowan Formation is 372-747 m thick, contains 6-26 coal layers, is 4.0-48.3 m thick, and has 3-20 mineable coal layers, which is 13.70-35.70 m thick. The Xishanyao Formation is 484-1083 m thick, contains 10-46 coal layers, is 11.3-47.7 m thick, and has 6-21 mineable coal layers, which is 7.7-34.2 m thick. The northeastern part of the Santanghu Basin is thin and consists of coarse clastic rocks with poor coal content. The southwest part is thicker and mainly composed of clastic rocks with good coal content. The Badaowan Formation is 300-1000 m thick, contains 1-21 coal layers, 2.0-50.0 m thick, and has 2-14 mineable coal layers, 3.7-46.7 m thick. The Xishan Yao Formation is 60 to 1250 m thick, contains 1 to 10 layers of coal, and can be mined from 2 to 8 layers. The Shuixigou Group in the Yining Basin has interbedded conglomerate, sandstone, and mudstone interbedded with carbonaceous mudstone and coal seams in the lower part, with a thickness of 105 to 890 m; the upper part is interbedded with sandstone, conglomerate, and mudstone interbedded with carbonaceous shale and coal seams. Thickness 100~300 m. The northern edge of the basin contains the best coal, with 14 to 36 layers and a thickness of 54.9 to 116.3 m. Generally, there are 2 to 3 layers and a thickness of 2.4 to 84 m. The Shuixigou Formation in the Yurdus Basin is composed of conglomerate and sandstone interbedded with siltstone, mudstone and coal seams. It is 457-563 m thick, contains 2-3 coal layers, and is 2.6-8.4 m thick.

Distributed in the Yanqi Basin and Kumish Basin in the Tianshan-Chifeng active zone, the Jurassic coal-bearing rock system is consistent with the Tarim Basin, and is the Middle and Lower Jurassic Kelasu Group, and the Lower Harbin The Mangou Formation is a seam of coarse sandstone and conglomerate intercalated with siltstone, mudstone and coal. It is 120-350 m thick, contains 3-11 layers of coal, and is 0.8-20.1 m thick. It is in pseudo-conformable contact with the underlying Middle and Upper Triassic Xiaoquangou Group. . The Tashidian Formation in the lower part of the Middle Jurassic is a coal-bearing stratum, consisting of sandstone, siltstone, mudstone intercalated with conglomerate, carbonaceous shale, and coal seams. It is 520 m thick, contains 9 to 66 coal layers, and is 64.8 m thick.

The Middle and Lower Jurassic developed in the Tianshuijingdong Basin east of the Tu-Ha Basin and Santanghu Basin and the Beishan Basin Group (Gongpoquan Basin and Wutonggou Basin) in the Tianshan-Chifeng active zone The coal-bearing rock series are all Dashakou Group. The Dashakou Group was originally called the Longfengshan Group, also known as the Shapoer Group. The lower part of the lower series is missing, the upper part is the Jijigou Formation, the lower part of the middle series is the Shapoquan Formation, and the upper part is the Qingtujing Formation. The lower part of its lithology contains coal, the middle part is dark mudstone, and the upper part is variegated sand and mudstone deposits with a thickness of more than 1500 m, and is in unconformable contact with the underlying Permian system. Above it is the Shazaohe Formation, which is in unconformable contact with the overlying Lower Cretaceous Chijinbao Formation and Xinminpu Group.

Distributed in the East Ujimqin Basin, Holingol Basin, and Xilinhot Basin north of the Xilinhot Massif in the eastern part of the Junggar-Xing'an active belt, the coal-bearing rock system lacks the lower Lower Jurassic, and the Lower Jurassic The upper and middle Jurassic are collectively called the Alatan Heli Group. The lower part is composed of sandy conglomerate, sandstone, and mudstone, 250 to 420 m thick, and does not contain coal; the upper part is made of mudstone, claystone, and fine sandstone intercalated with coal seams, and is 260 to 350 m thick. It contains 6 to 25 layers of minable coal and is 10.7 to 40 m thick. The lower part of the Xiwu Banner area contains 4 coal groups, and the coal seam is 20.7 m thick. The upper part has coarse lithology and does not contain coal.

The Songliao West Basin Group to the west of the Songliao Basin includes: Solon, Ulanhot, Zalut, and Linxi basins. The coal-bearing rock series is the Lower Jurassic Hongqi Formation, which is in unconformable contact with the underlying Permian and the overlying Wanbao Formation. , the upper Wanbao Formation coal-bearing seam is the lower part of the Middle Jurassic. The Hongqi Formation is a continental coal-bearing clastic rock deposit, with conglomerate, sandstone, and medium-acidic tuffaceous sandstone in the lower part, fine sandstone, siltstone, and coal seams interbedded in the middle, and siltstone, mudstone interbedded with sandstone, and thin coal seams in the upper part. Distributed in Wanbao, Linxi, and Zhalut areas, Tatayingzi in the north is 100 m thick, and Taipingchuan in the south is 780 m thick, with a maximum thickness of 1,300 m. It contains 22 layers of coal, 15 layers of mineable coal, and a single layer thickness of 1 to 1.5 m, with a maximum thickness of 2.55 m. The Wanbao Formation is composed of coal-bearing clastic rocks intercalated with intermediate-acidic volcanic rocks and pyroclastic rocks, with poor coal-bearing properties. The Songliao North Basin Group includes: Tahe, Huma, Heihe, and Dayangshu basins. The Jiufengshan Formation in the middle Upper Jurassic of the coal-bearing rock series is coal-bearing volcaniclastic rock and clastic rock intercalated with basalt, and is 43 to 400 meters thick. m. Distributed in the Huma-Heihe-Nenjiang area. Huola Basin contains 22 coal layers, with 4 mineable coal layers, with a single layer thickness of 0.14-22.99 m; Heibaoshan and Fungus Gas contain 15 coal layers, with 8 mineable coal layers, with a single layer thickness of 0.18-13.12 m; the big poplar contains There are 5 coal layers and 2 mineable coal layers, with a single layer thickness of 0.9 to 2.4 m.

The Songliao Basin is located in the eastern part of the Junggar-Xing'an active belt and the Tianshan-Chifeng active zone. It spans two tectonic units. The main body is located on the Nensong Massif, which is covered by Quaternary sediments. The upper overlying layer is mainly the depression overlay sedimentary layer from the Late Cretaceous to the Tertiary. Below it is the coal-bearing rock series from the Late Jurassic to the Early Cretaceous, covering the basement of the Pre-Sinian metamorphic rock and scattered Paleozoic rocks. Above the boundary and Triassic system. Drilling and geophysical prospecting have confirmed that there are four fault basin groups composed of north-northeast trending hidden belts, including Nenjiang-Yian-Qiqihar-Tailai-Taonan-Kailu North hidden belt, Baiquan-Laohugang-Daqing-Datong- Da'an-Tongliao-Naiman hidden zone, Qinggang-Zhaozhou-Songyuan-Qian'an-Changling hidden zone, Yichun-Suihua-Wangfu-Nong'an-Yangdachengzi hidden zone. The coal-bearing rock series in the Jurassic and Cretaceous rift basins are the Middle Jurassic Baicheng Formation, the Upper Jurassic Huoshiling Formation, and the Lower Cretaceous Shahezi Formation and Yingcheng Formation. The Baicheng Formation consists of conglomerate, sandstone, siltstone, mudstone, tuff, and thin layers of coal. The Huoshiling Formation is composed of volcanic rocks, pyroclastic rocks and clastic rocks intercalated with coal lines. The Jurassic fault basin in the western fault zone lacks the overlying Lower Cretaceous strata.

The Sanjiang Basin Group is located on the Jiamusi Massif in the Junggar-Xing'an active zone. It is a Yanshanian coal-bearing basin developed on the metamorphic basement of the Precambrian. A fault basin was formed in the Late Jurassic and the Early Cretaceous. In the early period, seawater invaded and the basin expanded. In the middle of the Early Cretaceous, the basin began to shrink. After the period, tectonic changes transformed the basin, and the basin was divided into multiple small sedimentary structural basins. The Jurassic remnant basins mainly include Hulin, Mishan and Jixi basins. The exposed strata include the Middle Jurassic Peide Formation, which is continental conglomerate, sandstone, coal seam and volcaniclastic rock. The Didao Formation of the Upper Jurassic consists of medium-coarse sandstone, fine sandstone, conglomerate, tuffaceous sandstone, and carbonaceous shale intercalated with thin coal seams, 0 to 630 m thick. The middle and upper Jurassic in the Hulin area are collectively called the Longzhaogou Group, including the Peide Formation of the middle Age and the Yunshan Formation of the upper part of the Upper Age. It is composed of alternating marine and continental phases of sandstone, siltstone, and mudstone interbedded with coal seams, and locally with rhyolitic horns. conglomerate. Yunshan and other places contain 7 to 22 layers of coal, with 3 to 4 minable coal layers, 6.77 m thick, and a single layer thick of 0.2 to 3.55 m, mainly thin coal seams.

The Jizhong Basin Group includes Shuangyang, Liaoyuan, and Huadian basins, located in the east of the Tianshan-Chifeng active zone and on the east side of the Songliao Basin. The basement of the Shuangyang Basin is composed of Carboniferous, Permian sedimentary rocks and Variscan granite, with the Late Triassic Dajianggang Formation coal-bearing rock series above it. The Jiuda Formation of the Upper Jurassic coal-bearing rock series is a lacustrine facies coal-bearing clastic rock deposit, with sandstone and mudstone intercalated with volcanic rocks and coal seams. It is 50 to 350 m thick, contains 2 to 4 layers of coal, and 1 to 2 layers of mineable coal. It is a thin coal seam with a thickness of 0.8 to 1.0 m.

The distribution characteristics of the Cretaceous coal-bearing basins in mainland China are not only very different from the Paleozoic craton coal-bearing basins, but also very different from the Triassic and Jurassic coal-bearing basins.

Cretaceous coal-bearing basins are mainly distributed in the Junggar-Xing'an active belt and the eastern part of the Tianshan-Chifeng active belt in the northeastern part of the continent and on the northern edge of the North China block. They are only scattered in the Gangdise-Tengchong active belt of the Tibetan-Yunnan plate. The Cretaceous coal-bearing basins are concentrated in the Early Cretaceous, and are mainly northeast-northeast faulted. Some of them overlap with the Late Jurassic faulted basins, or are covered by the late Cretaceous non-coal-bearing sediments. Layers overlap. Except for the Sanjiang Basin Group and the Cretaceous basin of the Tibetan and Yunnan Plate adjacent to the Wandashan Plate, which have alternating marine and continental facies deposits, the others are all continental facies deposits. Some basins contain volcanic rocks or pyroclastic rocks in the coal-bearing rock series.

The Hailar Basin Group is located in the eastern part of the Altai-Irtysh Paleozoic continental margin accretionary fold belt. To the north of the Irtysh-Derbugan fault zone is the Yanshanian sedimentary basin developed on the base of the Paleozoic fold belt. , the coal-bearing basin group spreads northeastward, including Manzhouli, Hulun Lake, Kulun Lake Basin, Ergun (left) Basin, Hailar North Basin, Xinbaoligedong-Bell Lake Hidden Zone, Hailar , Yakeshi Basin, Yimin-Xilinbeier, Honghuaerji Hidden Zone. The lower part of the basin is the Upper Jurassic Xing'anling Group, which is unconformable with the underlying Permian and pseudo-conformable with the overlying coal-bearing strata. The coal-bearing rock series is the Lower Cretaceous Zhalainuoer Group, which is divided into upper and lower groups. The upper Cretaceous strata are missing and covered by Cenozoic sedimentary layers. The Damoguaihe Formation in the lower part of the coal-bearing rock formation is a continental coal-bearing clastic rock deposit, 220 to 1050 m thick, with 5 to 20 layers of coal, 10 to 90 m thick, and a single layer 2 to 10 m thick. The main coal seam is located at The middle part of the coal-bearing section is 4 to 30 m thick, with a maximum thickness of 44.85 m. It is divided into three sections from bottom to top. The sandy conglomerate section is mainly distributed on the edge of the basin and is composed of conglomerate and sandy conglomerate intercalated with siltstone, mudstone and thin coal seams, with a thickness of 20 to 150 m. The silt-mudstone section is composed of mudstone and siltstone intercalated with fine coal. Sandstone and coal seams are 100-500 m thick; the mudstone section is mudstone, siltstone, silty mudstone intercalated with thin layers of medium-fine sandstone, siltstone, and local coal intercalation lines, 100-400 m thick. Zhalainuoer, Yimin, Dayan, Xihulitu and Baorixile have better coal content. The Yimin Formation in the upper part of the coal-bearing rock series is composed of mudstone, siltstone, and coal seams intercalated with sandstone and gritstone. It is 300 to 500 m thick and contains extensive coal. There are 3 to 4 coal groups, each coal group has 1 to 5 layers, and is 10 to 10 layers thick. 18 m, and the lower main coal seam is 10-50 m thick. Zhalainuoer, Yimin, Dayan, Huhenuoer and Honghuaerji contain better coal.

The Erenhot Basin Group includes the Honggeer Basin, the East Ujimqin-Erenhot, Holingrad-Xilinhot Hidden Zone, Holingrad, Bayanhua, Xilinhot Basin, Dalenol-Su Nite, Sunit-Ulijitu hidden zone, Wuchuan North, Wuchuan Basin, Xinbaolige Basin. The Erlian Basin Group is located in the eastern part of Inner Mongolia on the border between China and Mongolia. It spreads northeastward and has a wide range. It is mainly distributed in the eastern part of the Junggar-Xing'an active zone, south of the Irtysh-Derbugan fault zone, and across the Tianshan-Chifeng active zone. and the northern margin of the North China continental block. There are sporadic Jurassic strata exposed under the Erlian Basin Group, which are coal-bearing seams of the Middle and Lower Jurassic Alatan Heli Group. Above them are the Upper Jurassic Xing'anling Group, which is in unconformable contact with the overlying coal-bearing seams. The Lower Cretaceous Bayanhua Group and Huolinhe Group are the main coal-bearing seams, and the Upper Cretaceous strata are missing and covered by Cenozoic sedimentary layers. The Bayanhua Group is widely distributed and consists of sandy conglomerate, sandstone, siltstone, mudstone, and coal seams with a thickness of 500 to 2000 m. It is divided into 5 lithological sections. The coal-bearing section is located in the middle and is 82-316 m thick. It contains up to 48 coal layers and is 98.80 m thick. Shengli, Baiqinghua, Bayanbaolige, and Jilin Gol in the eastern part of the basin group have good coal content, with 2 to 7 coal groups, 6 to 11 coal layers, and more than 40 layers. The western part contains 1 to 3 layers of coal, 1 to 2 layers of mineable coal, and is 1.1 to 25.3 m thick. The coal-bearing rock series of the Huolinhe Basin located at the eastern end of the basin group is called the Huolinhe Group. It is a continental coal-bearing clastic rock deposit with a thickness of 1700 m and is divided into 6 lithological sections. The coal-bearing seams are located in the lower coal-bearing section and the upper coal-bearing section. .

The conglomerate section is located at the bottom and is composed of conglomerate, gritstone, and sandstone, with a thickness of 225 m; the lower mudstone section is composed of mudstone and siltstone with thin layers of sandstone, and is 100 to 500 m thick; the lower coal-bearing section is composed of sandstone, coal seams, mudstone, and silt. Sandstone contains 5 groups of dozens of layers of coal, 10 to 100 m thick, and the coal-bearing section is 300 to 600 m thick; the upper mudstone section is siltstone and mudstone intercalated with thin layers of oil shale, 150 to 350 m thick; the upper coal-bearing section is It is a seam of sandstone, siltstone, and coal, 400 m thick, containing more than 20 layers of thin coal, 10 m thick, and unstable; the sand-mudstone section is located at the top, and is sandstone, siltstone, and mudstone, 250 m thick. The coal-bearing rock series in the Wuchuan Basin is the Guyang Formation of the Lower Cretaceous. The bottom is conglomerate and sandy conglomerate intercalated with thin layers of mudstone and fine sandstone. The middle and upper parts are mudstone, shale and oil shale intercalated with sandstone, gypsum layer and calcareous mudstone. , the middle part contains two layers of lignite, and 4 to 7 layers of coal can be mined, with a maximum thickness of 5 to 18 m.

After the Yanshan period, the Hailar Basin Group and the Erenhot Basin Group are located in the continental tectonic-magmatic "activation" zone of the Pacific Ocean tectonic domain, belonging to the Greater Hinggan Range-Taihang Mountains-Wuling Mountains uplift zone, and were deposited in the Early Cretaceous coal-bearing rock series. Later, the uplift zone was regionally uplifted, and the Late Cretaceous sedimentary cover was missing. The Lower Cretaceous strata were directly covered by Cenozoic sediments. The coal-bearing rock series was not deeply buried, and the coal rock metamorphism was low. It was mainly lignite, and the coal-bearing seams were buried. It is shallow and lacks regional caprock, which is very unfavorable for the preservation of coal-bearing rock series.

The Songliao Basin is located in the eastern part of the Junggar-Xing'an active zone and the Tianshan-Chifeng active zone, and the main body of the basin is located on the Nensong Massif. During the Indosinian period, the block was uplifted and eroded, and intermountain depressions were formed locally in the Late Triassic. In the early Yanshan period, they were still small intermountain depressions, forming accumulations of coal-bearing volcanic rocks and clastic rocks. After the Middle Jurassic, there was a relatively strong After the Late Jurassic, the basin developed, which experienced two stages and two cycles. The first stage of the Yanshanian cycle includes the early rifting period in Huoshiling in the Late Jurassic, the deep rifting period in the Shahezi-Yingcheng period in the early to middle Early Cretaceous, and the rifting transformation period in the Dengluoku period in the late Early Cretaceous. , the main depression period from the Quantou-Nenjiang period in the Late Cretaceous and the basin shrinkage period from the Sifangtai-Mingshui period in the Late Cretaceous. The second stage of the Himalayan cycle includes the rifting period of the Paleogene and early Eocene and the depression period of the Oligocene to the late Quaternary. Mesozoic coal-bearing basins mainly developed in the deep faulting stage and early rifting stage. The Cretaceous coal-bearing basin is a superimposed rift basin inherited from the Jurassic rift basin. The coal-bearing rock series are the Shahezi Formation in the lower part of the Lower Cretaceous and the Yingcheng Formation in the middle part. The southern part of the basin is called the Shahai Formation and Fuxin Formation. , there are good coal-bearing seams on the periphery of the basin, and they are buried at different depths in the center of the basin. Deep oil and gas wells have drilled into these two sets of coal-bearing rock series. Since the Mesozoic, the Songliao Basin has been in the continental tectonic-magmatic "activation" zone of the Pacific Ocean tectonic domain. It has been in a state of stable subsidence since the late Yanshan period. It is a component of the Songliao-North China-Jianghan subsidence zone. The Dengluuku Formation in the late Early Cretaceous The covering-type sedimentary cover formed by its later subsidence is a favorable condition for the preservation of coal-bearing basins, and is beneficial to the formation, evolution and preservation of coalbed methane.

The Songliao South Basin Group, located in the uplift zone of the northern edge of the North China Block, includes the Fuxin Basin, Beipiao-Chaoyang Basin, and Chifeng Basin. They are all Cretaceous basins extending in a northeast-northeast direction. The formation age and mechanism of the fault basin are the same as those of the Songliao deep fault basin. It is only because the uplift zone on the northern edge of the North China continent was uplifted and folded after the Late Jurassic, and the sedimentary rock layers of the Early Cretaceous were exposed, which affected the coal-bearing rock series. The preservation is not very favorable. The coal-bearing rock series of the Early Cretaceous are the Shahai Formation and Fuxin Formation, and the coal-bearing strata on the southern edge of the Songliao Basin are also named after them. The Shahai Formation is a continental coal-bearing clastic rock deposit, divided into three lithological sections, 578 to 1370 m thick. The lower conglomerate section consists of thick layers of conglomerate and coarse sandstone intercalated with thin layers of fine sandstone and siltstone, 72 m thick; the middle coal-bearing section consists of thick, fine, and siltstone intercalated with multiple thin coal seams and coal lines, 145 m thick; the upper part is 145 m thick. The mudstone section consists of thin layers of mudstone, argillaceous siltstone intercalated with sandstone and conglomerate, and is 371 m thick. The Fuxin Basin contains 6 coal groups and 14 layers. The coal seams are thin. Except for one layer, which is 2 to 3 m, the others are 0.8 to 1.2 m. The Chifeng Basin (Pingzhuang, Yuanbaoshan) consists of conglomerate sections, mudstone sections, and coal-bearing sections, which are up to 1,000 meters thick. The coal-bearing section is 120 m, and the coal seams are thin and unstable.

Kangping is a seam of sandstone, sandy conglomerate intercalated with mudstone, siltstone, and coal, with a thickness of 300 to 670 m. The Fuxin Formation is a coal-bearing coarse clastic rock deposit, which is in integrated contact with the Shahai Formation and is 655 to 1200 m thick. From bottom to top it is the Gaode section, Taiping section, middle section, Sunjiawan section and Shuiquan section. The Gaode section is composed of siltstone and mudstone intercalated with gravelly sandstone, with 2 to 3 thin coal seams in the upper part, 20 to 250 m thick. The remaining four sections are all composed of gravelly coarse sandstone-sandstone siltstone interbeds-coal seams-siltstone to form a sedimentary cycle. The Shuiquan section at the top contains more than 10 layers of unstable thin coal, and the upper parts of the other three sections all contain extremely thick coal seams, which are the main coal-bearing sections. . All sections of the Fuxin Basin contain coal, with the thickest coal being 10 to 80 m, and most of them are coal seams greater than 10 m. Pingzhuang and Yuanbaoshan in the Chifeng Basin contain relatively good coal, and there are three main coal mining layers, 30 to 50 m thick, with a maximum thickness of 100 m.

The Mengzhong basin group in northern Hebei, located in the Tianshan-Chifeng active zone and the northern margin of the North China continental block, includes the Zhangbei, Duolunxi, Guyuan basin and Weichang basin. Although the basins are scattered, they are also Part of the entire northeast-northeast basin group. Except for the Duolunxi Basin and the Bayanhua Group of the Erlian Basin Group, the coal-bearing rock series is the Qingshili Formation, with the Upper Jurassic Jiufotang Formation below it and the Upper Cretaceous Shangjingzi Formation above it. It is an inland fluvial and lacustrine facies coal-bearing clastic rock deposit, 242 to 1000 m thick, with poor coal content. The Guyuan Basin has good coal content, with 34 coal layers and a thickness of 67.23 m. The main coal seam is 0.84-57.73 m thick, with an average thickness of 22.83 m.

The Sanjiang Jurassic and Cretaceous coal-bearing basin is located on the Jiamusi Massif in the eastern part of the Junggar-Xing'an active belt. It is a Jurassic and Cretaceous coal-bearing basin formed in the Yanshan period with the ancient continental block as the base. After the prototype basin was transformed by subsequent structural changes, the divided Hegang Basin, Tongjiang Hidden Zone, Shuangyashan, Baoqingnan, Qitaihe-Mishan, and Jixi Basin were formed. From the early Jurassic to the Early Cretaceous, coal-bearing basins experienced early rifting, middle-term expansion, and late-stage shrinkage development stages. A small rift basin was formed in the Early Jurassic; the rift expanded in the Middle Jurassic, forming coal-bearing clastic rocks and volcanic rock deposits in the Peide Formation; seawater intruded during the Didao period in the middle Late Jurassic, forming marine and alternating sea-continental phases. coal deposits. The period from the late Late Jurassic to the early Early Cretaceous was the basin expansion period. The sea area expanded and deposited marine and alternating sea-continental coal-bearing clastic sediments. During the Chengzi River period in the Early Cretaceous, seawater began to withdraw, forming the main coal-bearing seam system in the basin. During the Muleng period in the middle of the Early Cretaceous, the basin shrank and seawater withdrew, forming terrestrial and lacustrine coal-bearing sediments. The Cretaceous coal-bearing rock system of the Sanjiang Basin Group is the continental coal-bearing clastic rock deposits of the Chengzihe Formation of the Lower Cretaceous, with a thickness of 500 to 1000 m. The bottom is conglomerate and coarse sandstone, the middle part is medium-coarse sandstone, mudstone, coal seam, and siltstone. The upper part is siltstone, fine sandstone, mudstone intercalated with coal seams, and there are tuff interlayers. It contains 20 to 60 layers of coal, with a single layer thickness of 0.6 to 1.5 m, and a maximum thickness of 9.14 m. It can mine 20 to 40 layers of coal, with a thickness of 11.07 to 23.13 m. The number of coal-bearing seams increases from west to east, and the thickness of the coal seams increases. The middle part of the Lower Cretaceous is the Muling Formation, which is integrated above the Chengzihe Formation and in unconformable contact with the upper Huashan Formation. The Muling Formation is an intracontinental lacustrine facies coal-bearing deposit, with fine sandstone and mudstone intercalated with tuff and coal seams. The Boli and Jixi basins contain relatively good coal, with 1 to 17 coal layers, 1 to 9 minable coal layers, and a thickness of 3.78 to 7.77 m. The sandstone of the Lower Cretaceous Zhushan Formation is intercalated with mudstone, carbonaceous mudstone, and thin coal seams, and is 930 to 1230 m thick. Containing more than 20 layers of thin coal and coal lines, 2 to 3 layers of coal can be mined, and 6 to 8 layers of coal can be mined locally, with a thickness of 0.3 to 0.8 m, and the maximum thickness of a single layer is 15.1 m. During the Huashan Period of the late Early Cretaceous, volcaniclastic rocks and coarse clastic rocks were deposited in the basin, with a thickness of 500 to 2000 m. During the Ilin period of the Late Cretaceous, there were intense tectonic activities and violent volcanic eruptions. It is a set of variegated volcanic rocks and clastic rocks, 200 to 600 m thick, and is unconformable with the underlying strata. The Sanjiang Basin Group is located in the Changbai-Zhuguang uplift zone. It is in a regional uplift state in the late Yanshanian period. The basin shrinks, the subsidence is small, and the sedimentary layer thickness is thin. It is not very beneficial to the thermal evolution and preservation of the coal-bearing rock series. The Yanshanian and later periods Strong tectonic activity is also detrimental to the preservation of coal-bearing rock series.

The Jidong Basin Group is located at the eastern end of the Tianshan-Chifeng active zone, including Dongning, Yanji, Wangqing, Jiaohe, Shuangyang, and Liaoyuan basins. It is scattered and small in area. It is also a fault basin. Some basins have Jurassic or Late Triassic coal-bearing rock series under the Cretaceous coal-bearing rock series. The fault basins are not completely preserved, and the upper and lower basins are not superimposed perfectly. The lithology of each basin is different, and most of them are similar to nearby basins. The Shuangyang Basin is close to the Songliao Basin. The coal-bearing rock series is the Lower Cretaceous Yingcheng Formation, and beneath it is the Chang'an Formation. It contains 2 layers of coal, with a single layer thickness of 1 to 2 m, and the maximum thickness is 14.49 m. The coal-bearing rock series in the Dongning Basin is the Lower Cretaceous Naizishan Formation. The coal-bearing rock series in the Jiaohe Basin is the Naizishan Formation, which is a continental coal-bearing clastic rock deposit. The lithology is coarse at the bottom and fine at the top. It is 200-300 m thick and contains more than 20 layers of thin coal. 8-12 layers are locally mineable. Thickness 9.47~43 m. The overlying Wulin Formation is a continental coal-bearing clastic rock deposit, 150 to 450 m thick, containing unstable locally mineable coal. The Chang'an Formation of the coal-bearing rock series in the Liaoyuan Basin, Yanji, and Wangqing Basins is composed of coarse clastic rock intercalated with fine clastic rock, 200 to 900 m thick, and the lower part contains extremely thick coal seams, 4 to 10 m thick, with a maximum thickness of 33 m.

The Liaodong Basin Group located in the Liaodong Uplift Belt of the North China Block includes the Fusong West Basin and the Xinbin Basin. The coal-bearing rock series in the Fusong West Basin is the Chang'an Formation, and the coal-bearing rock series in the Xinbin Basin is the Sandy Basin. Sea group. Although the Liaodong Basin Group is located in the Liaodong Uplift Belt, they are all faulted coal-bearing basins formed in the late Yanshanian period. They have the same genetic mechanism and similar geological structural characteristics as the Cretaceous basin group distributed in northeastern China.