Except Silurian-Devonian and Lower Carboniferous strata, all strata in other periods are exposed (table 1- 1). Among them, the Mesoproterozoic, Cambrian, Ordovician, Carboniferous and Lower Cretaceous in Liupanshan are carbonate rocks.
Table 1- 1 Summary Table of Strata in Northern China
sequential
From the point of view of karst, this paper mainly summarizes the main characteristics and distribution law of soluble rock layers. According to the chemical composition of soluble rocks, this area can be divided into carbonate rocks, gypsum and rock salt. Carbonate rock is the most widely distributed soluble rock in this area, mainly deposited in Mesoproterozoic and Early Paleozoic, with a total distribution area of 685,000 km2. The Middle Ordovician in the eastern margin of Ordos Basin mainly produces gypsum and rock salt. In recent years, it has been found in Mizhi, Suide, Fugu and other places in northern Shaanxi. In addition, it is also distributed in some continental basins (such as Dawenkou basin in Shandong Province), mostly in the form of interlayer or thin layer.
1. Mesoproterozoic carbonate rocks
Mesoproterozoic. Including the Great Wall System, Jixian System, Qingbaikou System and Sinian System. Carbonate rocks mainly occur in Tuanshanzi Formation and Gaoyuzhuang Formation in the middle and upper part of Great Wall System, Wumishan Formation and Yangzhuang Formation in the middle and lower part of Jixian System and Tieling Formation in the upper part, Jingeryu Formation in the upper part of Qingbaikou System, and Sinian Ganjingzi Formation and Nanfen Formation in Fuzhou Bay area. Yanshan mountain range, northern Taihang mountain, Zhongtiaoshan area and the southwest edge of Ordos basin are the most developed, and the border area between Shandong, Anhui and Jiangsu and Luda are also distributed (Figure 1-2), which is a set of carbonate strata dominated by giant dolomite, with a total thickness of 505 ~ 9621m. Among them, dolomite and limestone of Gaoyuzhuang Formation in Great Wall System of Mesoproterozoic and flint dolomite of Wumishan Formation in Jixian System are the most stable, with the thickness exceeding 1000 m and the maximum thickness exceeding 3400 m.. Due to the later erosion and dissolution, the thickness of some areas may be less than 500 meters or even disappear. Although other formations are dominated by dolomite and limestone, they are slightly less stable, with more clastic rocks and smaller sedimentary thickness, generally 100 ~ 400 m, rarely exceeding 500m, Beijing Gaoyuzhuang Formation is 1005m, Wumishan Formation is over 2,200 m ... Jixian System gradually becomes thinner to the south, and Great Wall System is replaced by clastic rocks. The Great Wall System and Jixian System in the middle of this area are siliceous banded limestone with a thickness of 1230m. Qishan in Shaanxi, Jingfushan, Pingliang in Gansu and Qinglong Mountain in Ningxia are exposed in the southwest edge of Ordos Basin. Qishan is more than 2000 meters thick, Qianyang and Longxian are 500 ~ 700 meters, and Qinglong Mountain is 708 meters. ..
Neoproterozoic Qingbaikou carbonate rocks have small exposed area and thickness, and most of them are sand shale and impure carbonate rocks. Yishui and Yinan on the west side of Cangshan and Mu Yi faults in Shandong, and Zhuolu in the northwest of Hebei are dotted.
The Sinian system is mainly distributed in Yanshan, Xuhuai, Jiaoliao and western Henan, among which the carbonate rocks in Fuzhou Bay and Xuzhou in Dalian are thicker, the total thickness of argillaceous limestone and reef limestone in Wanlong Formation and Badaojiang Formation in Liaodong is more than 250m, and the Sinian strata exposed in Suxian to Sixian and Huainan-Fengyang mountainous areas in Anhui Province are mainly composed of calcium-magnesium carbonate deposits containing silicon. The lithofacies of Huainan and Huaibei are basically the same, but the lithology is slightly different. In the Sinian system from Yiyang to Pingdingshan in western Henan, the middle and lower parts are conglomerate, sand shale and argillaceous dolomite, and the upper part is moraine glutenite with a thickness of 544m m. The Sinian Tumen Formation in western Shandong is distributed in the Mu Yi fault zone and its west side, and is unconformity with Taishan Group.
2. Lower Paleozoic carbonate rocks
The early Paleozoic North China platform was divided into two parts, east and west, and the eastern part was dominated by carbonate deposits. The west is adjacent to Qinling and Qilian Trough, and the continuous sedimentary carbonate rocks, breccia and clastic rocks are mainly in the transitional stage of platform margin facies and basin facies. However, in the northern part of Ordos basin, Yimeng ancient land has been in sedimentary discontinuity.
Cambrian and Ordovician in Lower Paleozoic are mainly composed of carbonate rocks. In Ordovician, transgression was further expanded and carbonate rocks were more widely distributed. Because Ordovician and CAMBRIAN are continuous deposits, lithofacies palaeogeography is inherited. Among them, Shanxi and south-central Shandong are concentrated outcrops of Cambrian-Ordovician.
Widely distributed in CAMBRIAN area (Figure 1-3). The lower series is dominated by purple shale and sandstone, mixed with argillaceous dolomite, belonging to impure carbonate rocks. Upward carbonate purity increases, and carbonate deposition continuity is good. The lower part of Middle Cambrian is mainly sandy shale and sandstone with limestone (for example, Changping Formation in Beijing, 50m thick, Zhushadong Formation in Shandong, 5m thick); The middle of Zhangxia Formation is dominated by thick oolitic limestone, and the argillaceous composition in the northwest of the work area increases obviously, becoming argillaceous limestone or calcareous shale. Upper Cambrian Gushan Formation and Changshan Formation are dominated by argillaceous banded limestone and bamboo-leaf limestone, while Fengshan Formation is dominated by medium-coarse dolomite, with a total thickness of104 ~1891m.
Figure 1-2 Distribution map of Mesoproterozoic strata exposed in northern China
Figure 1-3 Distribution Map of Cambrian Strata in Northern China
The Lower Ordovician, including Yeli Formation and liangjiashan Formation, is mainly composed of medium-thick microcrystalline dolomite with chert nodules and chert bands. In the Middle Ordovician, except for the loss of Yimeng ancient land in the southwest of Henan Province and the north of Ordos Basin, it was widely distributed in the whole region (Figure 1-4), in which the Xiamajiagou Formation, Shangmajiagou Formation and Fengfeng Formation were a set of carbonate rocks and sulfate rocks, with three obvious sedimentary cycles, and each group transited from micrite dolomite sandwiched with gypsum to leopard limestone and micrite limestone with a total thickness of 420 ~1. Dolomite, argillaceous dolomite and gypsum deposits occur in the south of Tongchuan-Baode-Shijiazhuang-Dezhou line and the north of Hejin-Xinxiang. The banded zone bordering the Chyi Chin geosyncline of the North China Platform on the southwest edge of Ordos Basin includes Sandaogou Formation, Zhuozishan Formation and Sandaokan Formation in the Table Mountain area, and its lithologic bottom is a cloud facies deposit containing argillaceous dolomite, and upward is a set of medium-thin dolomite or limestone with relatively simple lithology, lacking two or three cycles and gypsum layers. At the same time, Pingliang Formation (including Duanjiaxia Formation in Longxian County, Kerimoli Formation in Table Mountain Area and Wulali Formation) and Beiguoshan Formation in Upper Ordovician (Tangwangling Formation and Rushizhong Formation) are also deposited on Sandaogou Formation in this area. The lithology is shale and a small amount of carbonate rocks, mixed with tuff, flint dolomite and slope collapse conglomerate in turn.
3. Carbonate rocks of Middle-Upper Carboniferous
The Middle-Upper Carboniferous is a coal-bearing deposit with alternating sea and land. The middle series is dominated by mud shale and bauxite, while the upper series is mud shale mixed with sandstone and limestone, containing minable coal seams. During the construction of coal-bearing clastic rocks in the Middle-Upper Carboniferous, the carbonate interlayer is thin and the number of layers varies from place to place, such as Xuzhou area 15 and Yangquan area 6. The total thickness of the Middle-Upper Carboniferous is generally 40 ~ 350m ... The thickness of the junction zone between Ordos Basin and Chyi Chin geosyncline changes greatly, and there is no sediment in Qishan area of Weibei, while the thickness of the Middle Series in Wuda area alone can reach 400 ~ 1205 m.
4. Lower Cretaceous carbonate rocks
Under the influence of Mesozoic Yanshan tectonic movement in the southwest of Ordos Basin, a set of piedmont calcareous conglomerate is scattered at the bottom of Cretaceous in front of Liupanshan and west of Weibei, and its calcareous composition can reach more than 80% in some areas, directly overlying the Middle Ordovician, and the maximum thickness can reach more than 200 m.
5. Paleogene carbonate rocks
It is mainly distributed in Tailai Basin and Dawenkou Basin in Shandong Province, and the second and third members of Guanzhuang Formation (E3) in Xintai, Mengyin and Pingyi areas. It is calcareous cemented calcareous conglomerate and marl, containing gypsum lenses, with a total thickness exceeding 1000 m, belonging to a set of foothill facies and lacustrine facies deposits. The limestone conglomerate in Xiazhang area of Dawenkou Basin in Tai 'an is 300 ~ 400 m, and the sunrise water can reach 1000m3 or more. The formation of Shangquanzhuangquan is closely related to the aquifer.
In addition, there is a set of conglomerate near Beijing Wali-China Geo University. The lithology of conglomerate is variegated conglomerate, such as gray, dark gray, khaki and purplish red. , with gravelly clastic structure. Gravel composition is mainly dolomite, flint and siliceous banded dolomite, accounting for about 80% ~ 90%. Followed by quartzite, marble, argillaceous limestone, and occasionally phyllite, oolitic limestone and volcanic rock. The conglomerate is covered by Quaternary, with a distribution length of about 8km, a width of about 2km and an area of about 16km2. This layer is considered to belong to Jurassic.
Second, the structural profile.
The north China platform is inner mongolian axis in the north, Chyi Chin geosyncline in the south and west, and the southeast is affected by the northward movement of the southeast side of the Tan-Lu fault, so the Carboniferous system is connected with the Yangtze platform from the south. It existed as an independent platform for a long time before the late Paleozoic, and was combined with Siberian platform and Yangtze platform at the end of the late Paleozoic and early Mesozoic.
Figure 1-4 Distribution map of Ordovician strata exposed in northern China.
Figure 1-5 Schematic diagram of the division of secondary structural units of North China Platform
The Indosinian movement began in the Late Triassic, and the North China platform entered the activation stage again, experiencing Yanshan movement and Himalayan movement. Especially since the Himalayan movement, the North China platform has suffered many strong collisions of the Indian plate and long-term compression and subduction of the Pacific plate, resulting in severe structural deformation. The present tectonic and geomorphological pattern is mainly controlled by Yanshan movement and Himalayan movement. As a primary structural unit, the North China Platform is divided into eight secondary structural units according to structural differences (Figure 1-5). They are Helan-Liupantai fold belt, Ordos platform depression, Shanxi fault uplift, Yanshan platform fold belt, Liaodong platform uplift, North China fault depression, Luxi fault uplift and Huai Yu platform fold belt.
1. Helan-Liupantai fold belt
From the point of geomechanics, Helan-Liupantai fold belt is a ridge with Qilu-Helan mountain structure, and the southern part of it is compounded with Longxi spiral structure. In the west, it is bounded by Qingtongxia-Guyuan fault in front of the North Liupan Mountain, which divides the North China platform and the Chyi Chin geosyncline, and the Aselang fault, which divides the Ordos Basin, is distributed in a north-south belt, with a width of 50 ~ 100 km from east to west and a length of more than 600 km from north to south. In addition to Liupanshan Mountain and Helan Mountain, there are Table Mountain, Qinglong Mountain, Wuyun Mountain and Longshan Mountain, which constitute the north-south ancient backbone belt. On the east side of this structural belt is the most stable Ordos block. During Yanshan period, under the strong thrust from west to east, a fault structure developed along the X joint (east side) of the early south-north anticline profile, which made the old strata on the west side of the wellbore overlap with the new strata on the east side, and often made the east wing missing (Figure 1-6).
Figure 1-6 Table Mountain-Bayin Aobao Structural Profile
The Helan-Liupantai fold belt consists of several main faults extending north and south, including Qinglongshan-Dangjiazhao fault, Qingtongxia-Guyuan fault, Chedao-Aselang fault and a series of secondary faults and associated fold structures (Table Mountain anticline in the north, Kabuqi anticline, Gundersen anticline, Qinglongshan anticline in the middle, Weizhou syncline, Jiulianshan anticline and Taitongshan in the south).
Each main thrust fault forms a nappe, and the peak of each nappe is mostly a uplift anticline, with old strata exposed and strong structural deformation, and the tail end is a depression syncline, with new strata exposed and weak structural deformation. From the peak end of uplift anticline to the tail end of nappe depression, it is characterized by gentle slope in landform and gentle three-dimensional syncline or monocline in structure, and there is no obvious boundary between them (Figure 1-6).
In the north-south direction, the tectonic belt is generally inclined to the north and to the south. Archean strata are widely exposed in the northeast and gradually inclined to the south, and most areas are covered by Mesozoic and Cenozoic. However, because some main thrust faults tend to gradually decrease and disappear to the south, and a new fault appears at the same time, there are four inclined terraces in the north-south direction in this area.
Carbonate rocks in this area are mainly distributed in the west wing of the north-south Longgang anticline.
2. Ordos Taiao
Ordos Tai 'ao is a giant tectonic basin with east-west asymmetry centered on Tian Huan syncline, which was gradually reduced from the Great North China Basin before the Late Paleozoic. On the east side is the west wing of anticlinorium in Luliang Mountain, and the stratum gently dips to the west; The western boundary is in high-angle fault contact with the Helan-Liupantai fold belt (Figure 1-7).
Figure 1-7 Schematic Diagram of East-West Geological Profile of Ordos Taiao
The carbonate rocks of Yimeng ancient land in the north are missing in this area, which are distributed in other areas, but buried by strata after the late Paleozoic. The burial thickness is shallow in the east and thick in the west, and the burial depth of syncline axis is over 4000m m. Carbonate rocks are only exposed on the west side of Lishi fault in the eastern margin.
3. Shanxi fault uplift
The west boundary of Shanxi fault uplift is Lishi fault, and the east boundary is Taihang piedmont fault, which was formed by the differential uplift of Mesozoic Indosinian and Yanshan periods and the shear-torsion of Himalayan period. Its topographic features can be summarized as "two mountains and one valley" in the northeast, and the regional geological structure is mainly controlled by anticlinorium Mountain in Luliang Mountain in the northwest, Qinshui syncline Mountain in the southeast and Fenhe Graben in the middle (Figure 1-8).
Figure 1-8 Schematic diagram of the east-west geological profile of Shanxi fault uplift
The strata of Luliangshan anticline, Archaean, Yuanguyu and Lower Paleozoic in the west are exposed along the axis and wings of the anticline, and there is no obvious boundary in the transition zone of Yishan slope in Ordos platform depression in the west.
Fenhe Graben (Wei Fen Graben) is developed in the middle of China, and consists of a series of NNE syncline fault basins, including Datong, Ding Xin, Taiyuan, Linfen, Yuncheng and Guanzhong Basin. Wei Fen Graben is mainly formed by inheriting the early east-west compressive fault and gradually expanding and descending under the Himalayan tension and torsion. The fault structures at the edge of the basin are controlled by modern geostress and early geological structures, and often take the form of ladder or graben-horst alternation. These faults are still in the active stage. The overall shape of Wei Fen graben and the local shape of some basins tend to be northeast-trending, while the south side is east-west. For example, Guanzhong Basin at the southernmost tip, Fenyang City on the south side of Taiyuan Basin and Shuoxian Basin on the south side of Datong Basin all show east-west trend and are controlled by nearly east-west compressive faults. For example, although the Zhangxingkou-Guanshan fault on the north side of Weihe Basin is a typical fault in the northern margin of Guanzhong Basin, the compressive fault plane where the Cambrian strata thrust above the Ordovician strata is still preserved in Kuishan area near its north side. The Shandi-Huangcaipo reverse fault that controls the outflow of Ma Po Shenquan and Xiakou Springs in the north of Fenyang City and the Gengzhuang fault in the north of Shuoxian Basin are all near east-west strike. This pattern shows that the Wei Fen Graben was developed on the basis of the early east-west compressive structure and under the extension of northwest-southeast direction in the later period.
Taihang Mountain uplift area in the east of Shanxi fault uplift is composed of Qinshui syncline, Fuping uplift (anticline) and Zanhuang uplift (anticline). The core of Qinshui syncline is mainly Triassic clastic rock; Archaean ancient metamorphic rock series are exposed in two other anticlines.
This area is the most exposed area of early Paleozoic carbonate rocks in northern China, mainly distributed along the two wings of the fold. The buried depth of carbonate rocks in the axis of Qinshui syncline and most graben basins can reach several kilometers to several kilometers.
4. Yanshan platform fold belt
The Yanshan platform fold belt includes two regions: Yanshan in the east-west direction and Liaoxi in the northeast direction. The geotectonic structure is located in the northern margin of North China Platform, adjacent to the Inner Mongolia axis in the north and the North China fault depression in the south. At the end of late Paleozoic, Indosinian and Yanshanian tectonic movements in this area left a large number of structural relics, especially Yanshan movement, which had the most far-reaching influence on the geological structure in this area. The results show that Mesozoic strata with a thickness of more than 35km are deposited in this area, and a large number of Mesozoic igneous rocks are distributed. The NE-trending fault-fold belt has large formation deformation and steep occurrence. The east-west compressive faults in Indosinian period changed into extensional faults after Yanshan period.
The geological structure pattern of Beijing can reflect the general situation of the tectonic movement of the Yanshan platform fold belt (Figure 1-9). Beijing is located in the western section of the North China Platform-Yanshan Platform Fold Belt. Today's main tectonic framework was laid by Yanshan movement and later transformed by Himalayan movement. A series of NE-NE uplifts and depressions are arranged alternately, and a group of nearly vertical extensional faults form the structural outline of Beijing area, namely Jingxi Uplift, Beijing Depression, Daxing Uplift, Dachang Depression and Yanqing Basin. The important faults include Yanhecheng-Nankou fault, Babaoshan fault, Nanyuan-Tongxian fault, Huang Zhuang-Gao Liying fault, Nankou-Sunhe fault, Yongdinghe fault and Shili Changshan fault. The main fold structures are Baihuashan-Jijishan syncline, Jiulongshan-Xiangyuliang syncline, Dashihe syncline and Beiling syncline.
Carbonate rocks in this area belong to Proterozoic and Cambrian-Ordovician, which are mostly found in discontinuous belts or fault blocks.
5. Liaodong Tailong
Liaodong Tailong is located in the eastern part of Liaohe River basin to the Yellow Sea, which is the southern extension of Changbai Mountain. This area is controlled by the sinistral Tanlu fault. The fault structures in this area are NNE and NNE, and NNE, and most of them are compressive faults. Carbonate strata are mainly distributed in the east-west composite syncline of Taizihe sag in the middle (Upper Paleozoic) and Fuzhou Bay area in the south (mainly Precambrian).
Figure 1-9 Structural Outline Map of Beijing
6. North China fault depression
The north and west sides of North China fault depression are separated by Yanshan platform fold belt and Shanxi fault uplift respectively, with Luxi fault uplift on the east and Xinxiang-Fengqiu-Lankao-Shangqiu-Mangshan NW-trending concealed fault on the south. After the Indosinian movement of the North China fault depression, it entered the active development stage of the continental margin, especially during the Yanshanian period, which made the fold faults very developed, accompanied by large-scale volcanic eruption and magma intrusion, and finally formed a series of secondary structures with alternating uplift and depression arranged in the northeast. Such as Jizhong Depression, Cangxian Uplift, Huanghua Depression, Chengning Uplift, Linqing Depression, Neihuang Uplift, Kaifeng Depression and Xu Tong Uplift. These faults and folds control the distribution and burial of carbonate strata.
The fault depression in North China mainly began to collapse in the early Cretaceous, and the carbonate rocks in the area mainly include Neoproterozoic (mainly distributed in the northern part of Cangzhou) and Early Paleozoic, all of which are buried under the loose layer, with a burial depth of 500 ~ 3000 m.
7. Luxi fault uplift
The western boundary of Luxi fault uplift can be divided into two parts, one part is Luzhong dome structure in the north, and the other part is Xuhuai arc structure in the south. The dome structure in central Shandong is composed of Mount Taishan, Lushan Mountain, Mengshan Mountain and Culai Mountain, and the central part is uplifted, and it gradually turns into hills and alluvial plains with some east-west Tailai Basin, Taozao Basin, Feicheng Basin, Yangzhuang Basin, Sishui-Feixian Valley and Xintai-Mengyin Valley in the northwest (Figure/KLOC-0 1- 10/0). The strata range from the middle Archean Taishan Group to the Early Paleozoic, Late Paleozoic and Meso-Cenozoic. The Xuhuai arc structure is composed of a series of composite folds striking northeast and protruding northwest, and compressive faults parallel to the fold axis, including Xiaoxian anticline, Sancha syncline, Huangcangyu-Laolongji anticline and fault structures parallel to the fold axis. After Paleozoic, the Tanlu fault in the east was in a state of continuous strike-slip movement from the east to the northeast, which had an important influence on the formation, development and evolution of the whole dome structure and became the power source of the basin and valley (the new stratum in southwest and the old stratum in northeast) in its interior.
Figure 1- 10 Geological Schematic Diagram of Luxi Fault Uplift
8. Yuhuaitai fold belt
The Yuhuaitai fold belt includes fan-shaped mountains, Xiong 'er Mountain, Waifangshan, Funiu Mountain and intermountain valleys, Huaihe Plain and Bagong Mountain in the southeast of Huainan from north to south, which is the residual vein of Qinling Mountain and the piedmont plain. This structure is located at the junction of North China Platform and Qinling Geosyncline. Macroscopically, this area is mainly composed of Mesozoic bulges and depressions controlled by large-scale and long-extending NW-trending faults (such as Zhongmu-Tongxu-Taikang fault, Jiyuan-Gongxian-Xuchang fault, Xin 'an-Yichuan-Wuyang-Xixian fault) and secondary east-west and northeast-east structural features. These structures compound and regulate each other, which controls the exposed distribution of carbonate rocks.