The largest and superimposed Tarim basin developed on the one of the three bigger craton, Tarim Craton, in China. The early Paleozoic is the heyday of its development and cratonization, and then changes to the different property basin. The reserved sedimentary strata of Neoproterozoicare recognized mainly in the local of outcrops periphery orogenic belts, but drilling core in the basin reveals them seldom. The proto-type of the initial Tarim Basinis always a mystery. The vast desert, huge-thickness of sedimentary strata, multiple tectonic movements, and a low quality of deep data are the keys to getting to know him. We comprehensive field outcrops, wells, seismic reflection profiles with higher SNRs and aeromagnetic data, recognized about 20 normal fault-controlled rifting depressions of the Cryogenian and Ediacaran, which scattered throughout the basin, and developed on the Precambrian metamorphic and crystalline basement. The structural framework is clearly different from that of the overlying Phanerozoic. The rifting depressions consist of mainly half grabens, symmetrical troughs and horst-grabens. From the northeast to southwest of the basin, they are divided into three rifting depression groups (RDG) with the WNW, ENE, and NW-trends that are mainly controlled by normal faults. From the Cryogenian to Ediacaran, most of the main inherited faults to active and eventually ceased at the end of the Ediacaran or Early Cambrian, while subsidence centers appeared and migrated eastward along the faults. They formed under the NNE-SSW oriented and NNW-SSE-oriented extensional paleo-stress fields (relative to the present) during the Neoproterozoic, and were accompanied by clockwise shearing. According to the analysis of the activities of syn-sedimentary faults, filling sediments, magmatic events, and coordination with aeromagnetic anomalies, the tectonic properties of the fault depressions are different and are primarily continental rifts or intra-continental fault-controlled basins. The formation of the rifting depression was associated with the initial opening of the South Altun-West Kunlun Ocean and the South Tianshan Ocean, which were located at the northern and southern margins of the Tarim Block, respectively, in response to the break-up of the Supercontinent Rodinia and the initial opening of the Proto-Tethys Ocean.Inthe RDG developedfluvial, shallow marine and carbonate platform facies, accompanied with multiple phases of magma activities and glaciations during the Cryogenian and Ediacaran. The structural architectures of interfaces between the Neoproterozoic and Cambrian are mainly angular and parallel unconformities in the RDG. Over the parallel unconformities in the RDGs are beneficial for the organic-rich and /or phosphorites of the Yuertus Formation of the Lower Cambrian. The main fault belts of RDGs also controlled the small platform margin and slope break belt of in the Cambrian. The Neoproterozoic and the Lower Cambrian petroleum systems of the basin might be controlled by the RDGs in the initiation of the Tarimcraton.

塔里木盆地新元古界的构造属性及结构构造长期以来存在争议,也是深层研究的重点及难题.通过区域探井和地震资料联合解释,结合航磁资料综合研究发现,塔里木盆地深层存在近20个大小不等的南华纪-晚震旦世裂陷.裂陷发育在前寒武纪变质结晶基底上,与上覆显生宙盖层构造格局迥异.受正断层控制呈半地堑、不对称地堑及垒堑相间的构造样式,从东北到西南可分为NWW、NEE、NW向展布的三个裂陷群,地层最大厚度可达4100m.从南华纪到震旦纪主要断裂继承性活动,断陷沉降中心沿断裂向东迁移,震旦纪末期至早寒武世断裂活动减弱至停止.断裂走向及沉降中心展布表明,新元古代塔里木陆块不同部位分别处于NNE-SSW、NNW-SSE向拉张古应力场(相对现今),并伴有顺时针旋扭作用.根据同沉积断裂的活动性差异、岩浆活动、裂陷充填沉积物及与航磁异常的协调性分析,裂陷的构造属性多以大陆裂谷及陆内断陷为主.裂陷的主要发育期在0.8～0.61Ga,其形成与南阿尔金-西昆仑洋、南天山洋的初始打开为响应,且是Rodinia超大陆主要裂解期的产物.

The Tarim Basin is the largest, oil-bearing, superimposed basin in the northwest of China. The evolution and tectonic properties of the initial Tarim Basin have been hotly disputed and remain enigmatic. The Neoproterozoic basin is covered by a vast desert and a huge-thickness of sedimentary strata, has experienced multiple tectonic movements, had a low signal to noise ratios (SNRs) of deep seismic reflection data, all of which have posed critical obstacles to research. We analysed four field outcrops, 18 wells distributed throughout the basin, 27 reprocessed seismic reflection profiles with higher SNRs across the basin and many ancillary local 2D and 3D profiles and aeromagnetic data. We found about 20 normal fault-controlled rifting depressions of the Cryogenian and Ediacaran scattered throughout the basin, which developed on the Precambrian metamorphic and crystalline basement. The structural framework is clearly different from that of the overlying Phanerozoic. The rifting depressions consist of mainly half grabens, symmetrical troughs and horst-grabens. From the northeast to southwest of the basin, they are divided into three rifting depression groups with the WNW, ENE, and NW-trends that are mainly controlled by normal faults. The maximum thicknesses of the strata are up to 4100 m. From the Cryogenian to Ediacaran, most of the main inherited faults to active and eventually ceased at the end of the Ediacaran or Early Cambrian, while subsidence centres appeared and migrated eastward along the faults. They revealed that the different parts of the Tarim continental block were in NNE-SSW-oriented and NNW-SSE-oriented extensional paleo-stress fields (relative to the present) during the Neoproterozoic, and were accompanied by clockwise shearing. According to the analysis of the activities of syn-sedimentary faults, filling sediments, magmatic events, and coordination with aeromagnetic anomalies, the tectonic properties of the fault depressions are different and are primarily continental rifts or intra-continental fault-controlled basins. The rifting phases mainly occurred from 0.8–0.61 Ga. The formation of the rifting depression was associated with the initial opening of the South Altun-West Kunlun Ocean and the South Tianshan Ocean, which were located at the northern and southern margins of the Tarim Block, respectively, in response to the break-up of the Supercontinent Rodinia and the initial opening of the Proto-Tethys Ocean.

To obtain the state of in-situ stress during the exploration of dense gas reservoir under Tarim Basin，the anelastic strain recovery(ASR) and the methods of drilling induced tensile fractures(DITF) were applied to measure the in-situ stress at depth of 7 km. The results show that the maximum principle stress is close to vertical and the medium and the minimum principle stresses are close to horizontal in SN-X well at 6 293–6 955 m depth. The orientation of maximum horizontal principal stress is NE51°–NE79°. The normal faulting stress regime exists in the inner Tarim Basin caused possibly by the stress releasing after the orogenic period or the escaping structures of Tarim basin by the long distance effect of Himalaya collisional orogeny. The effectiveness of ASR method at the ultra-depth was confirmed by the close results from the ASR and DITF methods. The ASR method has the advantages of low cost，high efficiency，and no depth and temperature limitation，and hence，will have broad prospect of application at ultra-depth in scientific drilling，unconventional oil and gas exploration and geothermal development.

The in-situ stress state in the Tarim Basin, Northwest China, down to 7 km depth is constrained using the anelastic strain recovery (ASR) method and wellbore failure analysis. Results are consistent between the two methods, and indicate that the maximum principal stresses (σ1) are close to vertical and the intermediate and minimum principal stresses (σ2 and σ3) are approximately horizontal. The states of stress at the studied wellbore is in the normal faulting stress regime within the Tarim Basin rather than in the compressional tectonic stress regime as in the periphery of the Tarim Basin, which explains the presence of the normal faults interpreted in 3-D seismic profiles collected from adjacent areas. Our results demonstrate that the ASR method can be used for rocks recovered from depths as deep as 7 km to recover reliable stress state information. The in-situ stress measurement results revealed in this paper will help future development of the petroleum resources and kinematics study in the Tarim Basin.

通过汶川科学钻探钻孔地质实体(岩芯)的构造研究、非弹性应变恢复法(ASR法)地应力测试,结合区域构造和汶川地震NW向余震带的综合分析,提出沿映秀-北川断裂走向的狭窄范围内存在一组NW-SE向构造,其总体产状为:走向N48°W,倾角中等,与映秀-北川断裂带的总体走向和ASR地应力测试获得的一组最大主应力方位(侧伏方向224°)和最大水平应力方位(44°)接近垂直.NW-SE向构造,除少数发育为宏观的断裂构造外,多数表现为密集的裂隙系(或隐断裂)和隐伏断裂,以逆冲性质为主,局部略具左行走滑特征.映秀-北川断裂两侧相向倾斜的NW-SE向裂隙系表明其两侧存在有方向相反的运动,映秀-北川断裂属两侧具有不同形成机制和相向位移的双侧走滑型断裂.映秀-北川断裂的同震垂向位移受NE-SW向构造和NW-SE向构造双重因素制约,在汶川地震的主震带与NW向余震带叠置部位具最大的垂向位移量.从时间尺度分析,在汶川地震的全过程中,仅开始时刻表现为自NW→SE方向的强烈逆冲作用,随后的主要时间段内均表现为沿断裂带方向的运动和自SW→NE方向的逆冲.NW SE向构造的形成是龙门山深部应力和能量长期积聚的结果,强震发生时,初始时刻的自NW向SE方向的强烈挤压,瞬即转换成自SW向NE方向的运动和强烈挤压.NE-SW向挤压构造应力场,是由NW-SE向挤压作用长期积累和诱导,并叠置在区域NW-SE向主导的挤压构造应力场之上的局部构造应力场,但在发震后,它主导了地震能量自震源区沿断裂走向向NE方向的快速传递和扩展及NW向强余震的发生,地震能量在NE-SW向强烈挤压过程中得到最终释放.因此,映秀-北川断裂在地震的不同阶段,其性质存在差异,在地震宁静期或弱震期(应力积累和闭锁期)以自NW往SE方向的逆冲性质为主,兼有右行走滑特征,但在强震期(应力释放和解锁期),除发震时表现为强烈的继承性逆冲作用,随后即转化为以平行断裂带走向自SW向NE方向的快速运动和扩展及自SW往NE方向的逆冲作用为主.

Three-dimensional in-situ stress is measured by anelastic strain recovery method (ASR) in Scientific Drilling well in Tengchong of Yunnan province. ASR method is an economic and practical new method, which is developed for three-dimensional in-situ stress measurement at great depth in recent years. In-situ stress state is obtained in depth from 720 m to 1098 m by ASR method. The results of measurement show that the maximum and intermediate principal stress is nearly horizontal, and the minimum principal stress is nearly vertical. The direction of the maximum horizontal stress is from 30° to 45°. Measurement results by ASR are compared with the focal mechanism solution. Comparison shows that the results by ASR are in good agreement with focal mechanism solutions. The stress state is conducive to strike slip movement for high-angle faults and to thrust movement for low-angle faults. This stress state is consistent with activity nature of earthquake faulting in Tengchong area. The results are meaningful for study in earthquake mechanism in Tengchong area.

Stress state around an earthquake fault is a key parameter to understand mechanisms of the fault rupturing. We tried to determine three-dimensional in-site stress orientations by anelastic strain recovery (ASR) measurements. As a case study, we applied this core based ASR method to two drill core samples retrieved from Wenchuan Earthquake Fault Scientific Drilling Project Hole-2. The core samples used for ASR experiments are chloritized diorite classified as a crystalline rock and retrieved from depths of 1,444 and 1,469 m in the hole-2, respectively. Anelastic strains of a core sample in nine directions, including six independent directions, were measured after its in situ stress was released by drilling. We obtained anelastic strain variation with time due to relaxation after its stress release. Then, the three-dimensional principal orientations of the in situ stress tensor at the two depths were successfully determined by determining the three dimensional principal orientations of the anelastic strain tensor. Our preliminary results showed both the stress regimes at the two depths are nearly strike slip faulting stress regime, and the maximum horizontal stress orientations are northwest–southeast or north-northwest–south-southeast. In addition, the results also suggested that the ASR method is applicable and useful for such in situ stress measurements in deep drilling projects.

In situ stress state becomes more and more significant with in-depth research on geodynamics and energy development. However, there has not been an economic and effective method developed to determine deep three-dimensional in situ stress. The Anelastic Strain Recovery (ASR) method is a newly developed technique that can determine three-dimensional in situ stresses. After the 12 May 2008 M s8.0 Wenchuan earthquake, the ASR method was used for the first time in mainland China to measure the in situ stresses in the WFSD scientific boreholes in Sichuan Province, China. In this paper, the basic procedure of the ASR method is introduced in detail and the compliances of ASR for boring cores are investigated. The results show that the maximum principal stress direction was NW64° at a measured depth (MD) of 1173 m (vertical depth 1151 m) in WFSD-1. The ratio of shear mode to the volume mode compliance of ASR was 2.9. And the three principal stresses at 1173 m MD in WFSD-1 are 43, 28 and 25 MPa. Combined with stress measurement results determined using other in situ measurement methods along the Longmenshan fault zone, the directions of the maximum horizontal principal stress changes from E-W to NEE-SWW to NWW-SEE when moving from NE to SW along the Longmenshan fault zone. This change is in agreement with the stress regime of the Longmenshan fault zone of the Wenchuan Earthquake, which supports a stress regime consisting predominantly of thrusts in the southwest and strike-slip in the northeast.

The Wenchuan Earthquake Fault Scientific Drilling Project was implemented rapidly after the great 12 May 2008 earthquake (Mw 7.9) to better understand rupture mechanisms of the seismic faults. The first borehole of the project, WFSD-1 was located in Hongkou Township, Dujiangyan City, Sichuan Province, China on the hanging wall of the Yingxiu–Beichuan fault, which underwent large dextral and vertical displacement during the earthquake. The near-vertical borehole was 1201m long. In-situ stresses were measured in rock samples from depths between 424 and 1173m drilling depth by the anelastic strain recovery (ASR) method. The average trend of the maximum principal stress σ1 was N309° (ranging from N291° to N325°), rotated with increasing borehole depth from NW–SE to WNW–ESE. The magnitude of the in-situ maximum principal stress was estimated to be 35.3MPa at the depth of 1173m. The relations between horizontal and vertical stresses are vertical stress σv>maximum horizontal stress σH>minimum horizontal stress σh at depths above 424m, σH>σh>σv at depths from 424m to 800m, and σH>σv>σh below the depth of 800m. These indicate that the stress states are in a normal faulting stress regime above 424m; a reverse faulting regime from 424m to 800m and a dextral strike-slip regime below 800m. The stress measurements from WFSD-1 are consistent with the focal mechanism solution in which the mainshock was dominated by thrusting accompanied by dextral strike-slip motion. The orientations of σ1 are roughly consistent with the tectonic displacement direction of the Longmenshan area, which provides further evidence of NW–SE movements representing compression of the Songpan–Ganzi block toward the Sichuan basin.

According to the GPS data, the fault-slip model for MW9.0 earthquake in March 2011 was inversed by using the finite element method. On the basis of the inversion, co-seismic displacement and stress fields were calculated, and the distribution of displacement and stress was given. The results show that fault-slip was up to 25 m. Northeast Japan was moved eastward by 1~6 meters, and the maximum displacement in the epicentral area was up to 24.25 m. After the earthquake, the surface was uplifted by about 5.6 meters near the epicenter. There was a depression area of 0.8 meters in the east coast of Northeast Japan. The calculated co-seismic surface displacement is consistent with GPS measurements. Stress was changed by the earthquake, resulting in the decrease of the post-earthquake stress. Stress change was about 9.9 MPa near the epicenter, 32 MPa in the depths, and less than 4.4 MPa in Northeast Japan. Earthquake-induced stress changes were mainly horizontal stress, whereas vertical stress changes were very small.

The variation of in situ stress before and after earthquakes is an issue studied by geologists. In this paper, on the basis of the fault slip dislocation model of Wenchuan Ms8.0 earthquake, the changes of co-seismic displacement and the distribution functions of stress tensor around the Longmen Shan fault zone are calculated. The results show that the co-seismic maximum surface displacement is 4.9 m in the horizontal direction and 6.5 m in the vertical direction, which is almost consistent with the on-site survey and GPS observations. The co-seismic maximum horizontal stress in the hanging wall and footwall decreased sharply as the distance from the Longmen Shan fault zone increased. However, the vertical stress and minimum horizontal stress increased in the footwall and in some areas of the hanging wall. The study of the co-seismic displacement and stress was mainly focused on the long and narrow region along the Longmen Shan fault zone, which coincides with the distribution of the earthquake aftershocks. Therefore, the co-seismic stress only affects the aftershocks, and does not affect distant faults and seismic activities. The results are almost consistent with in situ stress measurements at the two sites before and after Wenchuan Ms8.0 earthquake. Along the fault plane, the co-seismic shear stress in the dip direction is larger than that in the strike direction, which indicates that the faulting mechanism of the Longmen Shan fault zone is a dominant thrust with minor strike-slipping. The results can be used as a reference value for future studies of earthquake mechanisms.

The in-situ stress state of seismogenic fault after a strong earthquake is one of the important parameters for understanding the mechanism of the earthquake.The Wenchuan earthquake Fault Scientific Drilling project(WFSD) is a rapid response to the 2008 Ms 8.0 Wenchuan earthquake,which provided the test rock core for recognizing the stress state of the depth of Longmenshan fault on the eastern margin of the Tibetan Plateau.This paper focuses on the measuring instruments and processes of the anelastic strain recovery method(ASR) for the deep in-situ stress measurement.The anelastic recovery strains of seven different deep cores are in the range of 424-1173m in WFSD-1.The direction and magnitude of principal stress were determined and estimated,respectively.The dominant azimuths of maximum principal stress are between NW69° and NW35°,and the magnitude of principal stress increases with the increasing depth.

The stress existing in the crustal rock mass is called in-situ stress. The ASR (short for anelastic strain recovery) technique is widely used in deep 3-D stress measurements of rocks in crustal drilling, especially in seismic fracture zones with complex geologic conditions and broken formations. The 3-D ASR measurement results of the well WFSD-1 show that there are major differences between the Longmenshan foreland abduction zone and its underlying Longmenshan foreland basin and overlying Songpan-Garze block in terms of structure and stress state. On the whole, during the Wenchuan Earthquake, the Longmenshan foreland obduction zone dig-played SW to NE "laminar" flow of deep materials along the inter-crustal detached layer, and then turned into rapid vertical extrusion along the Yingxiu-Beichuan fault in the upper crust; while the Songpan-Garze block on its west side showed SE to NW gravitational slipping, and the Longmenshan foreland basin on its east side showed NE to SW strike-slip or dextral rotation. There has not occurred apparent or large-scale intracontinental subduction of the Yangtze block toward the Longmenshan orogenic zone on the eastern margin of the Qinghai-Tibet Plateau since the Late Cenozoic. The rapid and vertical up-going flow and extrusion of deep high-temperature low-viscosity materials in the Longmenshan foreland obduction zone is the direct cause for the occurrence of the May-12 Wenchuan Earthquake, while the intensive compression and crustal thickening of the Longmenshan foreland area as well as accumulation of deep stress and seismic energy as a result of E-trending expansion of the Songpan-Garze block are the main cause inducing abrupt change of the deep-seated shift field and rapid vertical extrusion of materials. The latter is the necessary condition for the former and not the direct result. The orientation of the principal compressive stress obtained by the ASR stress measurement is exactly parallel to the shift direction of the GPS coseismal velocity field, which indicates that the in-situ stress measured with the ASR technique may actually reflect or most approach the tectonic stress state during the earthquake.

The principle and calculation procedures for a lower cost and effective core-based stress measurement technique called anelastic strain recovery (ASR) technique are described. And then an example of its application to the hole-1 of Wenchuan Earthquake Fault Scientific Drilling Project (WFSD-1) is shown. Three principal stress magnitudes and directions of the hole-1 at the tested depth were determined. The maximum sigma(1) and middle principal stress sigma(2) are nearly horizontal, and the minimum principal stress sigma(3) is nearly vertical. The azimuth of the maximum principal stress is NW. At the vertical depth of 746 meters, the magnitude is 25.2 MPa for sigma(1), 21.5 MPa for sigma(2), and 18.5 MPa for sigma(3). This stress state can be interpreted as the same stress regime to make Longmen Shan fault to generate thrust and dextral strike-slip movement, which is consistent with fault movement of Wenchuan 5.12 Earthquake. The results obtained by ASR can be compared with that by focal mechanism solutions and other stress measurement methods. The example shows that, ASR method has great practical value. Especially in the larger drilling depth and complex geology conditions, stress relief method and hydraulic fracturing method can hardly be implemented, while ASR can obtain reliable data with good adaptability.

The South Altun fault, lying between the Neoarchean-Paleoproterozoic high-grade metamorphic rocks of the Altun Group and the Meso-Neoproterozoic low-grade metamorphic rocks in the Altun hinterland, is a roughly E-W-trending and slightly S-dipping high-angle large thrust fault. It has undergone two tectonic evolution stages, i. e. ductile deformation and fragile deformation. The ductile shear zone took shape in the Late Cambian, and shearing was intensive during the Middle Ordovician-Silurian (468.4 similar to 412.2Ma). In Early-Middle Devonian, Early Carboniferous, Late Permian and Early Jurassic periods, the shear zone entered the ductile deformation stage dominated by high and medium temperatures. With the elapse of time, the deformation temperature continued to decrease, and shearing was obviously weakened. After the Early Jurassic, the fault completely entered the tectonic evolution stage dominated by fragile deformation. However, it is indicated by the 491.3 +/- 4.6 similar to 413.8 +/- 8.0Ma calc-alkaline granites widely distributed north of the fault and the 500 +/- 10 similar to 519 +/- 37Ma eclogite and amphibole-mylonite exposed on the south side of the fault that there had been a lithosphere-scale subduction from south to north along the fault before a thrust-type ductile shearing of north polarity occurred. Therefore, this fault is an important convergance and collision zone of Early Paleozoic plates in the Altun hinterland.

This paper aims to analyze the tectonic framework of the Tarim Basin using regional tectonics.There is a large scale E-W fracture tectonic belt in the center of the Tarim basin,called the Central Tarim tectonic belt or the Central Tarim fracture belt whose geometric plane roughly corresponds to the Central uplift belt of the Tarim basin.Its eastern section extends to connect a group of large-scale near-vertical E-W ductile shear zones and fault zones in the Altyn Tagh orogenic complex,and its western section extends to intersect the binding sites of the West Kunlun orogenic belt and South Tianshan orogenic belt.Regarding its profile,it presents a back-thrust (anticlinal thrust) fracture combination whose formation began in the Early Paleozoic period and whose intense activities continued until after the Triassic Period.The fracture belt,which comprises natural features caused by the geographic thrusting,slipping and vertical squeezing,includes the major oil-bearing zones of the Tarim basin.The E-W highly positive anomaly zone,located roughly at latitude 39°30′~40°,is a large-scale E-W tectonic complex rock zone formed with a crystalline basement and represented by basic granulites,mafic dykes,and granite rocks,as well as superimposed with a Late-Proterozoic-Early Paleozoic active continental margin magmatic arc.The areas from the foreland basin of South Tarim to the Central Tarim fracture belt (the Central uplift belt of Tarim) is distinguished by the basic characteristics of an E-W tectono-magmatic belt,and superimposed with NEE faulted structure(fault rifts and fault sags),whose fracture assemblages are analogous to the fracture assemblages of South Altyn terrene at the south of the Central Altyn fault.The range from the north of the Central Tarim fracture belt to the foreland basin of the northern Tarim is a region characterized by a long-term down-warping.The conjunction belt at the West Kunlun-Tarim basin is manifested as the northward thrust faulting of the West Kunlun Mountains,the intense compression of its piedmont zone,and the sharp subsidence of the foreland basin of South Tarim.On the other hand,the conjunction belt at the West Tianshan Mountains-Tarim basin is manifested as the southward thrust faulting of the South Tianshan Mountains and uplifting at the back of the foreland basin of the northern Tarim,due to the strong northward subduction of Tarim massif against the orogenic complex of Tianshan Mountains.In its present state,the Tarim basin is featured by complex tectonic stress bearing the extrusion towards the basin space,squeezed by both north and south sides,sinistral strike-slip at the east,and dextral strike-slip at the west.Therefore,the formation of the current tectonic framework of Tarim basin is basically result of the four different types of tectonic stress fields mentioned above,which have attached multiple,intense transformations and superpositions against the pre-existing E-W directional tectonic texture.