Tarim movement (Z/Anz)
Jinning Movement in South China is an important tectonic movement in Late Proterozoic, which is represented by the unconformity between Sinian and Pre-Sinian. This movement may be related to a subduction and subduction activity in Tarim in late Proterozoic. The Neoproterozoic blueschist belt in Aksu is the relic of this subduction, and it has become the best preserved Precambrian blueschist in the world (Xiao Xuchang et al., 1990). Zhang et al. (199 1) believe that the northern margin of Tarim basin and the middle Tianshan, south Tianshan and Junggar-Kazakhstan plates converge to form a unified "Xinjiang ancient craton".
As for the time limit of Tarim movement, according to Xiao Xuchang and others' research on Aksu blue schist (1990), its metamorphic age is at least 800Ma, and Tianjin Institute of Geology and Mineral Resources has also obtained the metamorphic age of (962 12)Ma (according to Zhang et al. 19 1). The lower part of Sinian system in Keping Uplift is shallow sea-littoral feldspathic sandstone and sandstone with well-developed cross bedding, and the gravel composition of 2 ~ 3m conglomerate at the bottom is schist composition of Aksu Group, indicating that its angle is not integrated on greenschist facies metamorphic rock of Aksu Group (Zhang et al.,191; Xiao Xuchang et al.,1990; Chen Fajing et al., 1994), the bottom boundary of sinian system in this area should be 800Ma, so it is speculated that the time limit of Tarim movement is between 800 ~ 1000 Ma.
In Kuruktag area, the angle of Sinian slump gravity flow-turbidite facies clastic rocks and volcanic rocks is not integrated on the crystalline limestone of Qingbaikou Parganttag Group.
In the basin, seismic data reveal that the Sinian system is a set of dense reflection zones, which are located in the lowest part of the reflection of sedimentary caprock. Generally, there are 5-7 strong phases, which are connected intermittently and can be tracked and compared in the whole basin. Below it is the blank reflection or chaotic reflection of the pre-Sinian system. Therefore, the Tarim movement is characterized by the unconformity between Sinian and pre-Sinian reflections in the basin, which is extremely obvious in the whole Tarim basin, reflecting that the Tarim movement is very strong and affects the whole region. It is generally believed that the above-mentioned stably distributed reflection is the indication of the Upper Sinian series, and its thickness changes little, ranging from 400-1000 m. In some areas, there is still a set of reflection layers under this strong reflection wave group, suggesting that it may belong to the Lower Sinian series, but it is still difficult to accurately distinguish its attributes and distribution range.
Table 6-2 Comparison Table of Tectonic Movement, Strata and Seismic Wave Groups in Tarim Basin
(modified according to Chen Fajing et al. 1994)
The structural pattern of the top surface of the basement can be clearly seen on the buried depth map of the Sinian system in Tarim Basin (Figure 6- 15). In the northeast depression area, the minimum burial depth of Shaya uplift basement is about 5000m, Akkule basement is about 8000m, Caohu sag is as deep as14000m ... Maingard sag basement is16000m, and Awati fault depression basement is15500m. The Shuntuogole uplift between them is a "platform", and the buried depth of the basement is about1000 m. According to the data of Zhang Daquan et al. (199 1), the buried depth of the basement in Kuqa depression is 7000 ~ 9000m. ..
In the central uplift zone, the shallowest burial depth of Bachu uplift basement is about 4000m, Guchengxu uplift basement is about 5000m, Kartak uplift basement is about 6000m, and Tanggubasi sag basement is about10500m.
In the southwest depression area, the maximum buried depth of the basement of Yecheng Depression16000m, the maximum buried depth of the basement of Kashgar Depression17000m, and the shallowest buried depth of the basement of Maigaiti Slope is about 6000m. In the southeast fault uplift zone, the maximum buried depth of basement is only 5000 meters, which is the minimum buried depth of basement in the basin.
Obviously, Figure 6- 15 reflects the final appearance of the Sinian bottom (or basement top) after various stages of tectonic movement, rather than the result of this stage of Tarim movement. However, the Tarim movement has obviously created the embryonic form of the present structural framework of the Tarim Basin, such as Shaya Uplift, Maingard Depression, Awati Fault Depression, Kartak Uplift and Tanggubasi Depression. Some basement fault zones and structural weak zones were also formed at this time, such as Luntai fault zone and Tumuhun fault zone, which greatly controlled the structural deformation of the caprock in the later period.
Figure 6- 15 Buried Depth Map of Sinian System in Tarim Basin
6.2.2 Caledonian Movement
(1) Early Caledonian Movement
In the first scene (/Z), the limestone, siliceous shale and phosphorite of the Lower Cambrian Yurtus Formation are not integrated on the dolomite of the Upper Sinian Qigebulake Formation, and the dolomite at the top of the latter develops ancient karst (Zhang et al., 199 1). Thin-bedded siliceous rocks, dolomites and phosphorus-bearing mudstones of the Lower Cambrian Xishan Bulake Formation can also be seen in the Kuruktag uplift, which are parallel unconformity on the massive gravelly sandstone and microcrystalline dolomite of the Upper Sinian Hangerqiaoke Formation. Well Sha 4 on Yakela Fault Uplift in Shaya Uplift reveals that the top of Sinian system is karst breccia dolomite, indicating that there is sedimentary discontinuity at the end of Sinian system. This tectonic movement was the first act of the early Caledonian movement, and it was named Keping Ascending Movement (Zhang et al., 199 1), which may be related to the global sea level decline (,1994). Within the basin, seismic data reveal that the Cambrian and Sinian systems are mostly in integral contact, and it is speculated that there is parallel unconformity in the uplift area controlled by the basement, but they are in integral contact in the depression. The structural morphology of the bottom of Cambrian in Tarim Basin is very similar to that of Sinian, which reflects their inheritance.
In the second act (0 1 1/), although the CAMBRIAN and Ordovician are in overall or parallel unconformity contact in the outcrop area at the edge of the basin, the CAMBRIAN and Ordovician are reflected as a whole in most areas of the basin, but there is an obvious undercutting and upwelling phenomenon between the CAMBRIAN and Ordovician in Maingard Depression, and the CAMBRIAN is rapidly thinning towards the subsidence center. This movement belongs to the second act of the early Caledonian movement.
The minimum buried depth at the bottom of Lower Ordovician in Shaya uplift is 6000m, and Awati fault depression is13000m; Manga sag reaches14000m; ; Shuntuoguole Uplift is still a "platform", and the bottom of the Lower Ordovician is about 8000 meters deep. The buried depth of Lower Ordovician in Bachu Uplift is 2500 ~ 6000m, that of Kartak Uplift is 4000m ~ 7000m, and that of Tanggubasi Depression is 8500m. The buried depth of lower Ordovician in Kashi sag is15500m, and that of Yecheng sag is145000m.
(2) Middle Caledonian Movement
In the first scene (O2-3/O 1), there is a continuous transitional integrated contact relationship between the middle and upper Ordovician and the lower Ordovician in the outcrop area of basin margin uplift. However, seismic data show that there is obvious disharmony between the middle and upper Ordovician and the lower Ordovician in the basin. For example, we can see that the reflection interface has a downward cut between the pile numbers of 825000 ~ 865000 in EW500 seismic profile. But on the whole, the scope of this tectonic movement is not large. It can be seen from the structural map of the bottom of the middle-upper Ordovician that the minimum buried depth of the bottom of the middle-upper Ordovician in Shaya uplift is 5000m, and there is a large area of strata missing area; Buried depth of Awati fault depression12000m; ; Manga sag12500m; ; Shuntuogole Uplift is still a "platform", and the bottom of Middle-Upper Ordovician is buried at a depth of about 7000m. Central uplift zone, buried depth of middle-upper Ordovician in Bachu uplift1500 ~ 5000m; TangGubas sag is 7500 meters. The buried depth of middle-upper Ordovician in Kashi sag is15000m, and the buried depth of Yecheng sag is14000m.
In the second act (S/O2-3), it can be seen that the grayish green sandstone, siltstone and mudstone of the Kepingtage Formation of the Lower Silurian are unconformity on the underlying Ordovician carbonate rocks in parallel or micro-angle (Zhang et al., 199 1). In Kuruktag uplift, the angle of Tushbrak Formation of Lower Silurian is unconformity in lower Ordovician, Silurian-Devonian may be missing in southeast fault uplift and Altun uplift, and Silurian is not exposed in Tiekelike uplift.
Seismic data show that most of the northern Shaya uplift lacks Silurian system, while the southern Shaya uplift can be seen where Silurian system covers the top of the uplift. In Kartak uplift, it can be seen that Silurian and Ordovician are unconformity contact (Chen Fajing et al.,1994); In Maingard sag, the over-cutting and under-cutting phenomena of the reflection interface can also be clearly seen.
The above characteristics show that the second act of the Middle Caledonian Movement is a strong and influential tectonic movement, which makes the uplift pattern caused by the Tarim Movement more obvious. This tectonic movement may be a reflection of the passive transformation of the southern and northern margins of the Tarim plate into active margins, which transformed the Tarim basin from a Cambrian-Ordovician intracontinental extensional basin into an intracontinental compressional basin (Tang, 1994) or an intracontinental flexural basin (Chen Fajing et al., 1994).
This movement made Shaya Uplift, Kartak Uplift and Ancient City Market Uplift bigger. Because Maingard sag is filled with the extremely thick Middle-Upper Ordovician, the buried depth at the bottom of Silurian system in this sag (9000m) is less than that in Awati fault depression (11500m). The buried depth at the bottom of Silurian system in Bachu uplift1000 ~ 4500m, and the buried depth in Tanggubasi sag is 5000m. The buried depth of Silurian bottom in southwest China is still greater than 13000m.
It should be pointed out that there are three Silurian missing areas in Tarim, which are located in Shaya Uplift, Kartak-Gucheng Xuuplift and the eastern part of Maigaiti Slope. Many oil and gas fields have been found in the first two Silurian missing areas, and the third Silurian missing area may also have a good oil and gas prospect, which should be paid attention to.
(3) Late Caledonian Movement
In Keping Uplift, it can be seen that the purple-red, yellow-green sandstone and mudstone of Tataheta Formation of Middle-Upper Silurian are parallel unconformity on the gray-green sandstone and mudstone of Lower Silurian, indicating the existence of late Caledonian movement in this area. In Kuluktag Uplift, sandstone of Shugouzi Formation of Middle and Lower Devonian is parallel unconformity on clastic rock of Tushibulake Formation of Lower Silurian. Inside the basin, seismic data reveal that the reflection interface between Silurian and Devonian is in an integral relationship from top to bottom; However, in Manjia sag, from the pile number of EW500 seismic profile between 8 18 ~ 880, it can be clearly seen that Devonian system is superimposed and unconformity on Silurian system, indicating that late Caledonian movement is still displayed in the basin.
6.2.3 Tianshan Movement
The time limit of Tianshan movement is roughly equivalent to the crustal tectonic movement from devonian period to Late Permian, and is equivalent to Hercynian movement or Variscan movement widely used in Europe. In recent years, when studying the late Paleozoic tectonic movement in Tatangkemu Basin, it is still generally called Hercynian Movement or Variscan Movement (Kang Yuzhu,1986; Zhang et al., 199 1, et al., 1994), which also shows the mixed phenomenon of Hercynian movement and Tianshan movement. However, considering the regional characteristics of tectonic movement, we agree to use the term Tianshan movement. Although the Tianshan movement can be divided into at least two acts, and at most it can be divided into 12 acts (Yellow River source, 1986), in Tarim Basin, according to drilling and seismic data, the Tianshan movement can be divided into early, middle, late and late stages.
(1) Early Tianshan Movement (C/D)
It refers to a tectonic movement at the end of Devonian and the beginning of Carboniferous. The source of the Yellow River (1986) is called Kumish Movement, and Zhang et al. (199 1) is called Akkule Movement. This tectonic movement may be related to the subduction and collision closure of the South Tianshan Ocean and the North Kunlun Ocean, and its time limit is not completely consistent in different regions. In the south of Kumish, southern Tianshan Mountains, it can be seen that carbonate rocks of Cao Aihu Formation of Lower Carboniferous are unconformity with clastic rocks and volcanic rocks of Bochengzi Formation of Upper Devonian (Yellow River source, 1986), and this tectonic movement is widespread in southern Tianshan Mountains. In the Kuruktag uplift, the purple clastic rocks and carbonate rocks of the Nugustubulake Formation of the Lower Carboniferous are unconformity covered on the underlying stratum. The angle of coarse clastic rocks in the Lower Carboniferous and Upper Carboniferous Sishichang Formation is unconformity with Devonian red clastic rocks. On the Bachu Uplift, the glutenite, mudstone and limestone of the Lower Carboniferous Bachu Formation are parallel unconformity on the sandstone, siltstone and fine conglomerate of the Upper Devonian Tage Formation in Kizil. In Tiekelike Uplift and Aqike in front of the mountain, it can be seen that the angle of purple molasse-type coarse debris of Zizlav Formation in the upper part of Upper Devonian is not integrated on the underlying stratum. In Kunlun Mountain, it can be widely seen that after the Upper Devonian orogeny, the angle of molasse-type coarse clastic construction is not integrated on the underlying stratum. Jiang Chunfa and others (1992) believe that in the late Late Devonian, Kunlun generally rose to become a continent, and may spread to Tarim, Tianshan, Junggar, Qaidam, Qilian Mountain and East Qinling of Kunlun, thus forming the Devonian China ancient land.
Shaya Uplift was influenced by the early movement of Tianshan Mountains, and the reflection interface between Carboniferous and Devonian was obviously incised and overhung. The underlying Devonian, Silurian, Middle-Upper Ordovician and Lower Ordovician all suffered from strong denudation, and the angle of the upper Carboniferous in the underlying strata was not integrated in different periods (Figure 6- 14), and the middle-upper Ordovician, Silurian and Devonian suffered from denudation.
The early movement of Tianshan Mountain is the most prominent in the central uplift zone, which is characterized by strong uplift, erosion and fault (block) activity. Devonian has suffered extensive denudation, and Silurian has also suffered strong denudation in Guchengwei Uplift, Kartak Uplift and the eastern part of Maigaiti Slope. The middle-upper Ordovician in Tazhong 1 Well and Tazhong 4 Well were also eroded, and the angle of the upper Carboniferous in the underlying strata in different periods was incomplete. This tectonic movement formed a series of fault block structures in Kartak uplift, mainly thrust fault block structures, which are favorable oil and gas trap structures.
The early Tianshan movement further uplifted Shaya Uplift and eventually formed Kartak Uplift. On the pre-Carboniferous geological map, we can clearly see the performance and scale of the early Tianshan movement in Tarim Basin (Figure 6- 16), and the Carboniferous system is widely superimposed on the underlying strata in different times.
To sum up, the early Tianshan movement may be related to the closed collision between the South Tianshan Ocean and the North Kunlun Ocean, and it is one of the most important tectonic movements in the geological history of Tarim Basin. The first quasi-flattening process in Tarim basin was caused, and the Carboniferous covered the underlying strata. Compared with the pre-Carboniferous period, the structural characteristics and deformation characteristics of Carboniferous period have changed greatly. One of the most striking signs is that Maingard Depression, Kartak Uplift, Gucheng Xuuplift and Tanggubasi Depression are no longer as conspicuous as they were in the early days, and the sedimentary centers began to move westward.
(2) Middle Tianshan Movement (P 1/C)
It happened at the end of Carboniferous, and it is also called Karabian in Indonesia (Yellow River source, 1986). In Beishan area, malachite-like purple conglomerate and sandstone of Carata Formation of Lower Permian are unconformity on limestone, sandstone and andesite porphyrite of Yantan Formation of Upper Carboniferous. The tectonic movement in this period was widespread in Tianshan and Junggar areas, accompanied by magmatic activity (Yellow River source, 1986). In Tarim basin and its surrounding uplift areas, Carboniferous and Permian are mainly in integrated contact, and some parallel unconformity contacts can be seen, which may be related to the further westward movement of sedimentary center and the decline of sea level. On the structural map of the bottom of the Lower Permian, a large slope appeared from Kartak and Maingard to Awati, and its buried depth increased from 2,500m to10000m, the buried depth of the bottom of the Upper Permian in Bachu Uplift was 500-3,500m, the buried depth of Kashi Depression was12500m, and the buried depth of Yecheng Depression was16000m.
Figure 6- 16 Pre-Carboniferous Geological Map of Tarim Basin
(3) Late Tianshan Movement (P2/P 1)
It occurred at the end of Early Permian, and was called Xinyuan Movement in Tianshan Mountains (Yellow River source, 1986) and Shaxi Movement in northern Tarim Basin (Zhang et al., 199 1). On the southern slope of Yalke and in front of the southern Tianshan Mountains, it is generally seen that the clastic rock angle after the orogenic period of the Biyoulebao Guzi Group of the Upper Permian is not integrated on the volcanic rocks of the Kurgan Formation or the Xiaotikanlike Formation of the Lower Permian. The upper and lower Permian in Keping Uplift are in contact with each other as a whole. The fluvial sandstone and mudstone of Shajingzi Formation are covered on the basalt and clastic rocks of Kaipaizleke Formation of Lower Permian as a whole. Shajingzi Formation itself spans the early and late Permian and is in contact with the mottled clastic rocks of the upper Permian and carbonate rocks and clastic rocks of the lower Permian in the southwest of Tatanku and Tiekelike Uplift as a whole.
The late Tianshan movement was obvious in the northern part of Tarim basin, and the crust was strongly uplifted and denuded, accompanied by strong faults, folds and magmatic activities, and the distribution range of Upper Permian further retreated to the southwest.
(4) Late Tianshan Movement (T/P2)
It happened at the end of Permian, which is a continuation of the late Tianshan movement. In front of the southern Tianshan Mountains, it can be seen that the Lower Triassic Ohobulak Group is parallel or slightly unconformity with the Upper Permian Biyulebao Guzi Group (Chen Fajing et al., 1994). In the northern part of Tarim Basin, especially in Shaya Uplift, the Triassic angle is unconformity in different strata of Paleozoic. Due to the intense erosion of Paleozoic strata, the superposition of unconformities caused by early Tianshan movement and late Tianshan movement can be seen in the northern part of Shaya uplift. For example, Yakela fault uplift, Carboniferous, Ordovician, Cambrian and Sinian Upper Triassic angle unconformity; The Triassic angle of Akkule uplift is not integrated on the Lower Ordovician and Carboniferous. In the east of Yakela Fault Convex (Erbatai and the east area), the Jurassic-Cretaceous system is unconformity in the pre-Sinian system; In Shaxi Uplift, the Jurassic-Cretaceous angle is not on the strata of different layers in Paleozoic (Figure 6- 17).
Figure 6- 17 Pre-Mesozoic Geological Map of Tarim Basin
Late Tianshan Movement and Late Tianshan Movement are a continuous movement process, which was discussed by Chen Fajing (1994). We believe that the late Tianshan movement is characterized by faults, folds and magmatic activities, while the late Tianshan movement is marked by uplift and strong erosion. These two tectonic movements are the strongest in Shaya uplift, which is the setting period of Shaya uplift, and gradually weaken to the south. At this stage, due to the erosion of the surface by various external dynamic geological processes, the fluctuation amplitude of the surface gradually decreased and the height difference decreased, which led to the second quasi-flattening process in Tarim Basin, especially Shaya Uplift (Tang, 1993). The result of long-term strong denudation is reflected in the structural deformation model, that is, in Shaya uplift and its adjacent areas, the closed range of Paleozoic buried hills is very small, generally only tens of meters, mainly distributed on the unconformity surface.
On the pre-Mesozoic top () buried depth map, the tectonic pattern of alternating uplift and depression in Paleozoic no longer exists, the deformation characteristics of caprock changed, and the Tarim Basin appeared a three-point world. One is that the Kartak-Gucheng market is the top of the structure, with a uniform slope in the direction of Awati-Kuqa and an east-west direction as a whole. At the top of the structure, the minimum buried depth of unconformity is only 2,000m, which increases to 7,500m in Awati, 9,000m in Kuqa Depression and 4,500-6,000m in Shaya Uplift. Secondly, Bachu uplift is the top of the structure, showing a unified slope in Kashi-Yecheng direction, and the overall direction is northwest. The buried depth of unconformity surface at the top of the structure is 0 ~ 2000m, Kashi sag is11000m, and Yecheng sag is 9500m. Third, the Beiminfeng-Luobuzhuang fault uplift is the top of the structure, which inclines to the direction of Tian-Ruoqiang, roughly northeast. The buried depth of the unconformity surface at the top of the structure is 250 ~ 2000m, and the buried depth increases to 5000m towards the piedmont depression.
6.2.4 Indosinian Movement
It happened at the end of Triassic, and it was a very important tectonic movement, which may be related to the collision between Qiangtang plate and Tarim plate, and almost affected the whole Tarim basin and its adjacent areas. In Kuqa depression, Jurassic is parallel unconformity on Triassic, and the contact surface is uneven. The top surface of Upper Triassic is generally eroded, and lenticular breccia can be seen at the bottom of Jurassic (Chen Fajing et al., 1994). Shaya uplift was influenced by Indosinian movement, and the top stratum of Halahatang Formation of Upper Triassic was missing, and the Lower Jurassic was parallel unconformity in Triassic. In the eastern part of Maingard sag and the slope of Peacock River, the Triassic and Palaeozoic suffered from strong erosion, and the Jurassic angle was not integrated in the underlying Triassic, Carboniferous, Devonian, Silurian and Ordovician. Under the influence of Indosinian movement, the Triassic denudation pinchout line is distributed along the connecting line between Shen 1 well and Shen-2 well in the western margin of Awati fault depression. The Triassic system is generally circular, with no obvious long axis direction, and structurally monocline inclined to the north. The Indosinian movement denuded most of the uplift of the basin, and retreated to the northeast corner of the basin and the surrounding foreland depression in Jurassic, and the Tarim basin appeared the third quasi-flattening state. In the southwest of China, Triassic and Jurassic are in parallel unconformity contact.
The influence of Indosinian Movement on Mesozoic and Cenozoic petroliferous basins and tectonic framework in western China has been brilliantly discussed by some well-known scholars. Zhu Xia et al. (1983) regarded the Indosinian movement and the early Yanshan movement as the first stage of the reformation movement, and thought that the rifting fault in Tarim basin began in the late Triassic, the intermittent depressions in Qaidam and Turpan had been formed, and the western part of Qinling Mountains was closed by the Indosinian movement. Jiang Chunfa et al. (1992) pointed out that Indosinian movement and its opening and closing cycles only caused stratigraphic folds in East Kunlun area, but did not form obvious schistosity. The Indosinian movement at the end of the Middle Triassic not only slightly deteriorated the Middle Triassic and its underlying strata, but also unified the replacement bedding from Carboniferous to Middle Triassic and transformed the first-stage bedding from Mesoproterozoic to Early Paleozoic strata. The upper Triassic and Jurassic coal measures strata above the unconformity surface have not deteriorated, let alone displayed foliation, and the folds are wider. The Indosinian movement at the end of Late Triassic in West Kunlun resulted in the unconformity of marine Jurassic angle on the upper Triassic, and the Jurassic fold opened without showing metamorphism, while the lower Permian and upper Triassic formed closed folds and metamorphism with volcanic rocks. Therefore, the Indosinian movement is an important dividing point. Wang Hongzhen et al. (1990) believe that the collision between North Asia (Shitan, angara) and China-Korea-Tarim tectonic domain was completed in the late Hercynian-early Indosinian period; The last collision between China and Korea and Yangtze sub-tectonic domain occurred in Indosinian period; Obviously, the final closure of the whole Paleo-Tethys system and the formation of the United continent should be in Indosinian period. The first docking between Gondwana System and Eurasia took place during the Indosinian Movement, which made Qiangtang Block and the main part of Chinese mainland join together. To sum up, Indosinian movement is of great significance in the history of crustal evolution in Chinese mainland and its adjacent areas, and the crustal deformation caused by Indosinian movement shows certain continuity and inheritance with Hercynian period (Wang Hongzhen et al., 1990). The development of typical foreland depression in Tarim basin may have started after Indosinian movement, and the formation of a series of Jurassic sedimentary basins on the north and south sides of Tianshan Mountain and its interior is obviously the result of Indosinian movement.
6.2.5 Yanshan Movement
(1) Early and middle stage of Yanshan movement (K 1/J 1 or K 1/J)
It occurred at the end of early Jurassic and late Jurassic respectively, which may be related to the subduction and closure of the oceanic crust of the northern branch of the Middle Tethys and the northward merger of the Gangdise block and the ancient Asian continent. The Jurassic in Kuqa foreland depression is well developed, and the Lower Cretaceous Kapshaliang Formation is unconformity on the Jurassic in parallel or micro-angle. In Shaya Uplift and Maingard area, drilling data reveal that Jurassic only exists in the lower series, and the middle and upper Jurassic are missing. The lower Cretaceous is parallel unconformity on the lower Jurassic coal measures strata, which indicates that the early Yanshan movement and the middle Yanshan movement in this area are continuous. The structural form of the Lower Cretaceous is still a monocline inclined to the north, and its sedimentary range is much larger than that of Jurassic, which is generally characterized by overlapping unconformity contact with the underlying strata. In southwest China, the distribution of Jurassic and Lower Cretaceous is relatively limited, mainly developed in piedmont depression or pull-apart basin, and the Kizilsu Group of Lower Cretaceous is parallel or slightly unconformity with Jurassic.
(2) Late Yanshanian movement (K2/K 1 or E/K2)
It happened at the end of Early Cretaceous and Late Cretaceous respectively, which was equivalent to the second reform movement mentioned by Zhu Xia and others (1983). In this area, the upper Cretaceous and the lower Cretaceous are in an integrated or parallel unconformity contact relationship, and the micro-angle unconformity contact relationship can be seen locally. For example, in the crassus River, it can be seen that the glutenite of the Qomgram Group (K2-E) is not integrated on the red sandstone mudstone of the Lower Cretaceous Bashi Kichik Group (Chen Fajing et al., 1994). Seismic and drilling data reveal that there is mainly parallel unconformity contact between Upper Cretaceous-Paleogene and Lower Cretaceous in the vast area of central and northern Tarim.
In southwest China, the Upper Cretaceous Yingjisha Group and the Lower Cretaceous Kizilsu Group are in contact with each other in a whole or parallel unconformity, while the Lower Tertiary Kashi Group and the Upper Cretaceous Yingjisha Group are in parallel or angular unconformity, indicating that the late Yanshan movement in southwest China is stronger than the late Yanshan movement. Upper Cretaceous-Paleogene in southeastern China is parallel or unconformity with lower Cretaceous and underlying strata.
Upper Cretaceous-Paleogene belong to three independent foreland depressions, in which the deposits of Tabei and Southwest Tarim are superimposed on Kartak Uplift and Bachu Uplift, respectively, and are in overlapping unconformity contact with Lower Cretaceous and lower strata. The present Bachu uplift began to form in the late Yanshan period or the late Yanshan movement.
himalayaorogeny
(1) Early Himalayan Movement (N 1/E)
It occurred in the late or late Eogene, and was related to the subduction and closure of the main part of the Middle Tethys Ocean (that is, the ancient ocean between the Gangdise and the Himalayan block) and the collision between the Indian plate and the Eurasian plate (Wang Hongzhen et al., 1990). In the northern part of Tarim Basin, Miocene and the underlying Tertiary are in conformity or parallel unconformity contact (Zhang et al.,1991; Chen Fajing et al., 1994), but it can be seen from the center of the basin that the Miocene is unconformity in Paleogene and underlying strata. In Yecheng-Hotan area, southwest of China, Miocene Wuqia Group is in contact with Paleogene as a whole. However, in Kashi sag, the Sino-Singapore unification is generally parallel unconformity with gypsum or gypsum mudstone in different layers of Paleogene, and the local visible angle is unconformity contact. This tectonic movement caused strong subsidence in front of Tianshan and Kunlun mountains, accompanied by fault activity, and Bachu uplift basically formed and continued to uplift.
(2) Middle Himalayan Movement (N2/N 1)
It occurred at the end of Miocene, which was related to the further wedging of the Indian plate into the Eurasian plate, and was a strong tectonic movement. In Kuqa depression, the Kuqa Formation of Pliocene and Kangcun Formation of Miocene are parallel or unconformity (Chen Fajing et al., 1994). The Pliocene Artushi Formation and Miocene Wuqia Formation in Yecheng Depression are mainly in overall contact, while the Pliocene Artushi Formation in Kashi Depression is parallel or angular unconformity above Miocene Wuqia Formation.
Within the basin, the seismic data of Awati, Bachu and the west reveal that the reflection interface between Miocene and Pliocene has obvious undercutting and upwelling phenomena. Shajingzi, Aqia-Mutu earthquakes and the sub-Sandy-Mazatag fault zone continue to move, controlling the deposits on both sides of the fault. Bachu uplift is further uplifted, and the piedmont depression is further strongly flexed and settled.
(3) Late Himalayan Movement (Q/N2)
It happened at the end of Pliocene, when the Indian plate wedged into the Eurasian plate and the Qinghai-Tibet Plateau rose rapidly. Zhu Xia and others (1983) regarded it as the third reform movement. This tectonic movement caused the Tianshan Mountains and Kunlun Mountains to be strongly squeezed and shortened, greatly uplifted, and thrust into the basin. Before the southern Tianshan Mountains, the Quaternary angle of Kuqa Depression was unconformity in Tertiary, and there were strong folds and faults under the unconformity surface, forming a foreland fold thrust belt. Keping uplift formed imbricate thrust belt along the detachment surface of Lower Cambrian. The faults on both sides of Bachu uplift continued to move, and the uplift eventually formed, forming thrust nappe on the shaft of the uplift. There are also inherited activities in Shajingzi fault and Kalayurun fault around Awati fault depression. In front of Kunlun Mountain, due to Pamir's northward invasion, not only a strong compressive thrust was generated in the piedmont depression, forming a fold thrust belt, but also a large strike-slip component, which made the piedmont fold thrust belt unfold in a wild goose. In the southeast, Altun Mountain Uplift and East Kunlun Mountain overthrust into the basin, accompanied by strike-slip components. The Qira-Luobuzhuang fault zone in the front of the southeast fault uplift belt is active strongly, and the Beiminfeng-Luobuzhuang fault is finally finalized. In the abdomen of the basin, it is mainly manifested by weak regional uplift, fold and fault activity.