The formation and evolution of the Tuha Basin can be divided into three stages as follows.
1. Late Permian-Triassic - the stage of formation of the foreland basin after the arc
The Hercynian movement led to the folding of the Carboniferous-Early Permian strata, which constituted the folded basement of the Tuha basin. Late Permian Tuha Basin around the boundary of the mountains to the south of the Jyolotag Mountain to the north of the backwash is dominated by the Jyolotag Mountain as a pre-arc accretionary fault body from south to north to the Turfan plate on top of the formation of its mountains in front of the back-arc foreland depression zone; the northeast edge of the formation of the Harlik Mountain and to the southwest of the extrusion; the north of the Bogdaha Rift Trough from the east to the west began to return to the north and south side of the foreland depression band **** with a centralized uplift band. From the remnants of the Permian, Triassic isothermal map analysis, in the line of the present central fault zone, the distribution of the nature of the island chain of ancient uplift, separating the basin into the north and south, the southern depression zone is shallow, seismic data analysis can be distinguished from west to east for the Tocxon Depression, the Ruxi low convexity, the Shanshan Depression, the Kumu convexity and Tarnan Depression, the stratigraphy of the overall southern thick and north, in the Late Permian and the Late Triassic there are two sedimentary interruptions There are two sedimentary discontinuities in the Late Permian and Late Triassic. According to the analysis of aeromagnetic data and seismic data, there are two to three depressions in the northern depression zone, namely, Taoshuyuanzi depression in the west, Aktash depression in the middle and Caohu depression in the east. Since the uplift of Bogda Mountain has not yet affected the whole Turpan depression, the scope of the two sides of the depression zone is larger than that of the present-day Tuha Basin. It is possible that the northwestern part of the basin had some kind of unified relationship with the Junggar Basin.
At this time, the Hami depression has an independent tectonic unit, and the north-east oriented fracture of Sidaogou on its west side controls the Late Permian-Triassic deposition of Hami, with a large thickness of deposition and a full range of stratigraphy, which is the most complete development of Late Permian-Triassic stratigraphy in the Tuha Basin.
2. Jurassic-Palaeoproterozoic - foreland basin formation stage
The Indo-Chinese movement at the end of the Triassic period was a strong tectonic movement in the basin with the nature of filling in and replenishing, which changed the tectonic appearance of the two foreland depression zones in the north and south of the basin since the Late Permian period, making the former Jurassic system in the basin the most complete development of stratigraphy. The former Jurassic system in the basin was stripped and flattened to form a quasi-plain. The Juelotag Mountains stopped their activities, and the southern depression zone was uplifted to form a regional slope, which constituted part of the southern basement of the basin and became the main source area for the deposition of the Cenozoic strata in the basin. The Turpan depression is unified into one. The northern part is affected by the uplift of Bogda Mountain, and the mountain front continues to subside and receive Jurassic deposits.
Early and middle Jurassic when the entire basin for the marsh, plains phase deposition. The depositional center of the Turpan depression gradually migrated from the west and south to the northern mountain front.
Toward the end of the Middle Jurassic, the northwest edge of the basin of the Kara Wucheng mountain uplift, in the western part of the depression to form the Burga Bulge and the Ira Lake - Kendeke high terrace belt, the northern depression belt became the main sedimentary belt of the Tuha Basin, accompanied by the uplift of the Bogda Mountain, began to enter the stage of the class of foreland basins. Foreland-like basin refers to the basin developed on the basis of the original foreland basin, and the sectional characteristics and sedimentary assemblage have similarities and some differences with the foreland basin. During this period, the northern Bogda Mountain washed from north to south, and the southern part formed a slope with gradual tilt, and developed a wedge-shaped stratum with northern thickness and southern thinness, and the depositional center was located in front of the northern mountain. At the end of the Jurassic period, with the uplift of the northwestern Kara Wucheng Mountains, a series of north-east oriented positive tectonic zones were produced, which divided the original unified depression into three small sub-depressions with north-east axes, namely, the western Shengjintai Depression, the central Qudong Depression, and the eastern Caohu Depression.
The Cretaceous-Palaeoproterozoic is the stage of basin equalization and subsidence, the Early Cretaceous depression is in the state of extrusion and uplift, in the surrounded by the mountains, the climate of the dry and hot conditions, the depression further contraction of the scope of the depressions, deposited a set of riverine deposits dominated by the red coarse clastic rocks, the western Torking area by the impact of the Irahu Fault tectonic subsidence, and once again became a depression, the east of the Hami area and the northern pre-mountain main depression. Hami area and the northern mountain front is mainly manifested as the extrusion of Bogda Mountain from north to south, the extrusion intensity is not large, only in the mountain front to form a series of parallel with the mountain trend of the extrusion of alluvial tectonics. The Shanshan Group and the Taoshuyuanzi and Grape Gully Formations, which are dominated by the fluvial and alluvial-floodplain phases, were widely covered with sedimentation, overlying the different layers of the underlying strata, and the depositional range was expanded to the whole basin, where the Tuha Basin was completely unified, not through the catchment of the lake basin, but through the connection of the extensive fluvial phases and the floodplain-alluvial fan.
3. Neoproterozoic to Quaternary - the formation of the New Tianshan Intermountain Basin stage
The uplift of the New Tianshan Mountains is related to the collision of a series of landmasses and the southern margin of the ancient Asian continent, and its final strong uplift is related to the collision of the Indian plate, this period, the Bogda Mountains form a "V" type uplift constitutes a "V" type uplift constitutes a "V" type uplift. During this period, the Bogda Mountain formed a "V-shaped uplift to form a fan-shaped structure, and to the Tuha Basin and Junggar Basin on both sides of the retrograde overturning, resulting in changes in the pattern of the depression of the Turpan Depression, from north to south, the strong extrusion stress in the north of the depression belt to produce along the Badaowan Formation, the Xishanyao Formation, two sets of coal strata of the large cover slip, and the front belt of the central backslope belt, the western part of the Flaming Mountain tectonic zone will be the early victory of the Jintai Depression into two. The western part of the Flaming Mountain tectonic belt divides the early Shengjintai depression into two, forming the Shengbei depression in the northern part of the mountain and the Shengnan depression in the southern part of the mountain. At the same time, due to the unevenness of the sliding action, four near-north-south translational faults were generated in the northern depression belt, which divided the depression belt into five blocks, and there were differences in the direction of the tectonic belt, local tectonic style, and quantity of the blocks, and the migratory changes of the secondary depressions were only terminated when the north-south and east-west tectonic patterns of the Turpan Depression were finalized. The Hami depression is less affected by the Bogda Mountain, and still maintains the net-like tectonic pattern of north-east and north-west tectonic intertwining.
With the Himalayan movement, the Bogda Mountain was strongly uplifted and washed away to the south, and correspondingly, a series of uplift and folding occurred in the basin, especially in the northern depression zone, which generally suffered from uplift and erosion. The Quaternary system in the basin is basically a set of flood-alluvial phase of millstone deposition, no lake basin development, marking the basin has entered the stage of extinction.
Figure 1-5 Tectonic hierarchy of the Tuha Basin (showing the basin structure)