新疆及邻区Pn速度层析成像

利用新疆及邻区2万多条Pn射线的走时资料,采用层析成像的方法反演该地区上地幔顶部的Pn速度结构.主要结果是:①新疆地区平均h速度为.2km/s,高于中国大陆地区的平均值(.0km/s),速度变化量从-0.3km/s到0.2km/s.②准噶尔盆地是明显的高Pn速度区,高速区与地貌形状吻合较好,最大值达.4km/s;塔里木盆地整体上呈现高速异常二者都可能与盆地是稳定地块、构造活动和变形较弱有关.③在盆地与山脉的交接带即主要的构造活动带,存在较低的Pn速度,可达7.9km/s.④塔里木南缘中部存在一显著的低速区,可能与岩浆活动和构造活动较强有关.⑤上地幔顶部波速各向异性整体上盆地中心较弱,边缘地带较强.新疆南部波速的各向异性可能是因印度板块对欧亚大陆的碰撞使地幔物质向北蠕动的结果.     

A finite difference study on the basement structure beneath the Tianshan Orogen

We use the Pg seismic phase along the Korla-Jimsar profile across the Tianshan orogen and the 3D finite difference method to inverse the velocity structure of the upper crust beneath the basement of this mountain. Based on the velocity structure, the Korla-Jimsar profile can be divided into three parts, i.e. the north edge of the Tarim basin, the Tianshan orogen, and the south margin of the Junggar basin. Within the Tianshan there is a pattern of four convexities and three concavities, which correspond to the southern Tianshan, the Yanqi basin, the middle Tianshan, the Turpan basin, and the Bogda Mountains. In the north edge of the Tarim basin, the basement is about 10km deep with small lateral variations of velocity. In the Tianshan the velocity varies greatly laterally. The basement depth of the Yanqi basin is 6 km, which becomes shallow rapidly northward, and almost to the surface at the middle Tianshan. South to Kumux there is a small intermountain basin, where the maximum basement depth is 3 km, and also turns very shallow near Kumux. The Luntai fault, which bounds the Tarim basin and Tianshan, has vertical dislocation of about 5 km. The Turpan basin is covered with so thick a sediment that its basement is 7 km deep. The boundary fault between the Tianshan and Turpan is the Bolohoro fault which is characterized by quick deepening basement and 7 km vertical dislocation. In the Junggar basin the basement is 8 km deep. On the Korla-Jimsar profile, the velocity distribution of the upper crust and the structure are featured by NS symmetry on both sides of the axis of the Middle Tianshan, consistent with the deep structure revealed by this profile. It means that the Tarim basin and the Junggar basin underthrust toward the Tianshan from south and north, respectively. Such a structural style is different from that of another profile, i.e. the Xayar-Burjing profile, suggesting that there may be an important tectonic boundary between these two profiles.     

New Early Cretaceous paleomagnetic results from Qilian orogenic belt and its tectonic implications

Lower Cretaceous red sedimentary rocks from the depositional basin of East Qilian fold belt have been collected for a paleomagnetic study. Stepwise thermal demagnetization reveals two or three components of magnetization from dark red sandstones. Low-temperature magnetic component is consistent with the present Earth Field direction in geographic coordinates. High-temperature magnetic components are mainly carried by hematite. The mean pole of 19 sites for high-temperature magnetic components after tilt-correction is λ=62.2°N, φ=193.4°E, A95=3.2°, and it passes fold tests at 99% confidence level and reversal tests at 95% confidence level. The paleopole is insignificantly different from that of Halim et al. (1998) from the same sampling area at the 95% confidence level. Compared with paleomagnetic results for North China, South China, and Eurasia, our results suggest that no significant relative latitudinal displacement has taken place between Lanzhou region and these blocks since Cretaceous time. Remarkably, the pole of Lanzhou shows a 20° clockwise rotation with respect to those of North China, South China, and Eurasia. Geological information indicates that the crustal shortening in the western part of Qilian is greater than that in eastern part. In this case, the clockwise rotation of sampling area was related to India/Eurasia collision, and this collision resulted in a left-lateral strike-slip motion of the Altun fault in north Tibetan Plateau after the Cretaceous.     

天山造山带岩石圈密度与磁性结构研究及其动力学分析

库尔勒—吉木萨尔剖面横跨塔里木盆地北缘、天山造山带和准噶尔盆地南缘.沿剖面完成了重磁联合反演,获得了岩石圈二维密度结构与二维磁性结构.结果发现,塔里木盆地与准噶尔盆地向天山造山带对冲.在地壳范围内,塔里木盆地北缘与准噶尔盆地南缘的平均密度较高,天山造山带的地壳平均密度较低.天山造山带具有较高的磁化强度,尤其表现在准噶尔盆地南缘至天山造山带中部的整个地壳范围内,预示着天山南北可能具有不同的构造演化历史、构造运动方式以及构造运动强度.在塔里木盆地与天山造山带以及准噶尔盆地与天山造山带的接触部位的上地幔顶部分别发现了低密度体,推测在塔里木盆地由南而北向天山造山带“层间插入与俯冲消减”,以及准噶尔盆地由北而南向天山造山带俯冲的过程中塔里木盆地北缘和准噶尔盆地南缘下地壳物质被带进天山造山带上地幔顶部.库尔勒—吉木萨尔剖面岩石圈二维密度结构与磁性结构为天山造山带的构造分段提供了岩石圈尺度的依据.     

新疆地区S波分裂研究h

利用国家地震台网及中国地震局ldquo;十五rdquo;期间在新疆地区布设的宽频地震台站记录到的远震波形数据,采用最小能量法和旋转相关法分别对SKS、 SKKS震相进行了偏振分析,计算了台站下方介质各向异性的分裂参数:快波的偏振方向（phi;）和慢波延迟时间（delta;t）．研究结果表明,塔里木盆地北缘、天山造山带和阿尔泰造山带大多数台站的快波偏振方向与台站下方构造走向方向接近,其快慢波分裂延迟介于0.8——1.8 s之间. 这与印度 欧亚碰撞导致的岩石圈缩短有关．相比而言,塔里木盆地和准噶尔盆地内部的各向异性强度明显要弱,表明其自前寒武形成以来并没有经历强烈的变形作用．阿尔金断裂带附近台站下方各向异性快波方向与断裂带的走向具有很强的相关性,表明该断裂已经切穿整个岩石圈．      

塔里木盆地中生代古地磁研究及构造意义

采用主成分分析方法、线性谱法和LINFIND方法，分离了塔里木盆地中生代岩石的多磁成分，并采用岩石磁学和褶皱检验等方法研究了剩磁稳定性．对于塔里木盆地三叠系、侏罗系的岩石其携磁矿物以磁铁矿为主，具有两组次生磁性成分和一组原生剩磁成分；原生剩磁成分的解阻温度为550℃，而两组次生成分的解阻温度分别为175－250℃和300一375℃，可能为生物剩磁和次生氧化形成的剩磁．白垩纪岩石的携磁矿物以亦铁矿为主，同样具有两组次生剩磁和一组原生剩磁；两组次生剩磁分别为现代地磁场的粘滞剩磁和岩石变形过程中形成的构造剩磁．塔里木盆地中生代早期极移不明显，处于一个相对平静时期；侏罗纪至白垩纪盆地则主要表现有一定规模的南移，伴有顺时针旋转运动。盆地白垩纪的古纬度与现在纬度相比，仍存在17°－20°左右的纬度等，这一纬度差是通过白垩纪以后塔里木板块的北向漂移和板块北部造山带的压缩及边界的大型走滑作用来缩小；另外，压实作用也可能是由垩纪磁倾角变低的一个原因。     

中国西南思茅地体中部白垩纪古地磁结果及陆内地壳变形特征

对我国西南地区思茅地体中部巍山和五印地区白垩纪地层进行了详细的岩石磁学和古地磁研究,获得了两个地区的高温剩磁分量并通过了褶皱检验.巍山剖面特征剩磁方向为Ds=64.3°,Is=48.5°,k=54.6,α₉₅=4.7°;五印剖面特征剩磁方向为Ds=15.4°,Is=44.8°,k=212.0,α₉₅=4.6°.通过思茅地体磁偏角变化与兰坪-思茅褶皱带构造线迹变化的相关性分析,确定思茅地体内部差异性旋转变形受控于思茅地体弧形构造带的形成和演化.通过青藏高原东南缘走滑断裂带活动年代分析,确定兰坪-思茅褶皱带蜂腰构造部位形成于两期构造事件,早期构造变形与东喜马拉雅构造结北北东向挤压缩进有关,后期构造变形与川滇微地块发生顺时针旋转时南向挤出运动有关.以华南板块稳定区白垩纪古地磁极为参考极,计算得出巍山和五印相对于华南板块分别发生了10.5°±6.0°和3.8°±4.9°的南向运移量.通过选取思茅地体内部构造形态较稳定的巍山和普洱地区白垩纪古地磁极为参考极,计算得出五印相对于巍山和普洱分别发生了3.4°±5.0°和3.1°±5.4°的北向纬向运移,表明五印和和巍山之间自印亚碰撞以来经历了较大规模的北向地壳缩短变形作用.     

Large N-S convergence at the northern edge of the Tibetan plateau? New Early Cretaceous paleomagnetic data from Hexi Corridor, NW China

Nine Early Cretaceous paleomagnetic sites have been collected in the Yumen area of the Hexi Corridor (NW China). Magnetic directions isolated at lower temperatures fail the fold test, and lie close to the geocentric axial dipole field direction before tilt correction. High temperature components are carried by magnetite and/or hematite, all with normal polarity, and pass the fold test. The average paleomagnetic pole from the nine sites is at λ=75.5°N, φ=169.9°E (A₉₅=7.7°). These results are consistent with those from other areas of the North China block (NCB), but significantly different from those from the Qaidam Basin on the southern side of the Qilian Mountains. They suggest that: (1) the Yumen region behaved as a rigid part of the NCB since at least the Early Cretaceous; (2) 740±500 km of north-south directed convergence has taken place between the NCB and Qaidam, within the Qilian Mountains and (3) extrusion of Qaidam was accompanied by a 23±5° relative rotation with respect to North China. This is larger than implied by the maximum left lateral slip on the Altyn Tagh fault system. The same data imply some 1000±800 km of Cenozoic motion between the Tarim and NCB blocks, which were so far believed to have formed a rigid entity since at least the Jurassic. One interpretation could be that all Tarim and Qaidam Cretaceous paleomagnetic samples from red beds, but not those from Yumen and the NCB, suffered significant inclination shallowing, as observed in Cenozoic red beds from Central Asia. So far, we do not find support for this possibility. Possible tectonic interpretations include: (1) the existence of a large, as yet uncharted, tectonic discontinuity between Tarim and the NCB in the vicinity of the desert corridor near 95-100°E longitude; (2) the occurrence of significant deformation within southwestern Tarim, to the north of Yingjisha where paleomagnetic sites were obtained, or (3) persistent clockwise rotation of Tarim with respect to the NCB, for at least 20 Ma, at the rate found for current block kinematics.     

滇西兰坪盆地白垩纪-早第三纪古地磁结果及其地质意义

通过对滇西兰坪盆地白垩系地层的古地磁采样和室内退磁研究,揭示出一组高温特征分量,９５％正倒转检验和９９％置信度下的正褶皱检验,说明这组高温分量很可能代表岩石形成时的原生剩磁．对比国际标准地磁极性年表,发现南新组与阿尔比期、赛诺曼期和土仑期相当,而虎头寺组则相当于晚白垩世的三冬期和康尼阿克期．与中国东部的白垩纪古地磁数据比较．进一步证实了晚白垩世华南与印度支那地块存在明显的纬度差,这一事实说明了印度支那地块在印度板块与欧亚板块的碰撞及进一步挤压下,印度支那地块在早第三纪沿红河大断裂走滑千余公里,并伴随着１５　－２０　的顺时针旋转．     

Syn-tectonic sedimentation and its linkage to fold-thrusting in the region of Zhangjiakou,North Hebei,China

The timing of the "Yanshanian Movement" and the tectonic setting that controlled the Yanshan fold-and-thrust belt during Jurassic time in China are still matters of controversy. Sediments that filled the intramontane basins in the Yanshan belt perfectly record the history of "Yanshanian Movement" and the tectonic background of these basins. Recognizing syn-tectonic sedimentation, clarifying its relationship with structures, and accurately defining strata ages to build up a correct chronostratigraphic framework are the key points to further reveal the timing and kinematics of tectonic deformation in the Yanshan belt from the Jurassic to the Early Cretaceous. This paper applies both tectonic and sedimentary methods on the fold-and-thrust belt and intramontane basins in the Zhangjiakou area, which is located at the intersection between the western Yanshan and northern Taihangshan. Our work suggests that the pre-defined "Jurassic strata" should be re-dated and sub-divided into three strata units: a Late Triassic to Early Jurassic unit, a Middle Jurassic unit, and a Late Jurassic to early Early Cretaceous unit. Under the control of growth fold-and-thrust structures, five types of growth strata developed in different growth structures: fold-belt foredeep type,thrust-belt foredeep type, fault-propagation fold-thrust structure type, fault-bend fold-thrust structure type, and fault-bend foldthrust plus fault-propagation fold composite type. The reconstructed "source-to-sink" systems of Late Triassic to Early Jurassic,Middle Jurassic and Late Jurassic to early Early Cretaceous times, which are composed of a fold-and-thrust belt and flexure basins, imply that the "Yanshanian Movement" in our study area started in the Middle Jurassic. During Middle Jurassic to early Early Cretaceous times, there have been at least three stages of fold-thrust events that developed "Laramide-type" basementinvolved fold-thrust structures and small-scale intramontane broken "axial basins". The westward migration of a "pair" of basement-involved fold-thrust belt and flexure basins might have been controlled by flat subduction of the western Paleo-Pacific slab from the Jurassic to the Early Cretaceous.     

Paleomagnetic constraints on the tectonic history of the major blocks of China duing the Phanerozoic

Paleomagnetic study of China and its constraints on Asia tectonics has been a hot spot. Some new paleomagnetic data from three major blocks of China. North China Block (NCB), Yangtze Block (YZB) and Tarim Block (TRM) are first reported, and then available published Phanerozoic paleomagnetic poles from these blocks with the goal of placing constraints on the drift history and paleocontinental reconstruction are critically reviewed. It was found that all three major blocks were located at the mid-low latitude in the Southern Hemisphere during the Early Paleozoic. The NCB was probably independent in terms of dynamics. its drift history was dominant by latitudinal placement accompanying rotation in the Early Paleozoic. The YZB was close to Gondwanaland in Cambrian, and separated from Gondwanaland during the Late-Middle Ordovician. The TRM was part of Gondwanaland, and might be close to the YZB and Australia in the Early Paleozoic. Paleomagnetic data show that the TRM was separated from Gondwanaland during the Late-Middle Ordovician, and then drifted northward. The TRM was sutured to Siberia and Kazakstan blocks during the Permian, however, the composite Mongolia-NCB block did not collide with Siberia till Late Jurassic. During Late Permian to Late Triassic, the NCB and YZB were characterized by northern latitudinal placement and rotation on the pivot in the Dabie area. The NCB and YZB collided first in the eastern part where they were located at northern latitude of about 6°—8°, and a triangular oceanic basin remained in the Late Permian. The suturing zone was located at northern latitude of 25° where the two blocks collided at the western part in the Late Triassic. The collision between the two blocks propagated westward after the YZB rotated about 70° relative to the NCB during the Late Permian to Middle Jurassic. Then two blocks were northward drifting (about 5°) together with relative rotating and crust shortening. It was such scissors-like collision procedure that produced intensive compression in the eastern part of suturing zone between the NCB and YZB, in which continental crust subducted into the upper mantle in the Late Permian, and then the ultrahigh-pressure rocks extruded in the Late Triassic. Paleomagnetic data also indicate that three major blocks have been together clockwise rotating about 20° relative to present-day rotation axis since the Late Jurassic. It was proposed that Lahsa Block and India subcontinent successively northward subducted and collided with Eurasia or collision between Pacific/Philippines plates and Eurasia might be responsible for this clockwise rotating of Chinese continent.     

An intramontane pull-apart basin in tectonic escape deformation: Elbistan Basin,Eastern Taurides,Turkey

The Elbistan Basin in the east-Central Anatolia is an intramontane structural depression in the interior part of the Anatolide-Tauride Platform. The Neogene fill in and around Elbistan Basin develops above the Upper Devonian to lower Tertiary basement and comprises two units separated by an angular unconformity: (1) intensely folded and faulted Miocene shallow marine to terrestrial and lacustrine sediments and (2) nearly flat-lying lignite-bearing lacustrine (lower unit) and fluvial (upper unit) deposits of Plio-Quaternary Ahmetçik Formation. The former is composed of Lower-Middle Miocene Salyan, Middle-upper Middle Miocene Gövdelidağ and Upper Miocene Karamağara formations whereas the latter one is the infill of the basin itself in the present configuration of the Elbistan Basin. The basin is bound by normal faults with a minor strike-slip component. It commenced as an intramontane pull-apart basin and developed as a natural response to Early Pliocene tectonic escape-related strike-slip faulting subsequent to post-collisional intracontinental compressional tectonics during which Miocene sediments were intensely deformed. The Early Pliocene time therefore marks a dramatic changeover in tectonic regime and is interpreted as the beginning of the ongoing last tectonic evolution and deformation style in the region unlike to previous views that it commenced before that time. Consequently, the Elbistan Basin is a unique structural depression that equates the extensional strike-slip regime in east-Central Anatolia throughout the context of the neotectonical framework of Turkey across progressive collision of Arabia with Eurasia. Its Pliocene and younger history differs from and contrasts with that of the surrounding pre-Pliocene basins such as Karamağara Basin, on which it has been structurally superimposed.     

帕米尔东北侧地壳结构研究

1998年在帕米尔东北侧伽师及其周边地区完成了两条深地震宽角反射/折射剖面. 结果表明,西昆仑、塔里木和天山在地壳速度结构、构造特征上显示出较大差异. 塔里木块体具有稳定地块的地壳结构特征,地壳平均速度较高(6.5km/s). 向南进入西昆仑,地壳明显增厚,厚度可达0km左右,且地壳平均速度偏低(6.0-6.2km/s),偏低的地壳平均速度主要来源于相对低速度的下地壳结构,反映了西昆仑褶皱系下地壳介质的特征. 向北进入天山后,地壳同样明显增厚,但增厚的程度低于西昆仑下,约为50-55km. 天山地壳同样具有明显低的平均速度(6.2km/s),显示了天山地壳相对"软"的特征,但天山地壳偏低的平均速度来源于广泛分布于中地壳的低速度层和速度偏低的下地壳. 在印度块体向北强烈推挤的作用下,该区地壳遭受强烈的不均匀变形,塔里木块体向南插入西昆仑下,向北插入天山下,形成了该区强烈地震频繁发生的深部构造环境.     

印欧大陆碰撞前亚洲大陆南缘古位置再研究:林周盆地上白垩统红层的古地磁新结果

拉萨地块林周盆地白垩系红层的古地磁数据一直都有较大争议.过去认为磁倾角变浅可能是造成这些分歧的主要原因.我们在林周盆地设兴组背斜两翼进行了系统的古地磁采样,15个采样点的特征剩磁分量在倾斜校正和倾伏褶皱校正后平均方向为D=339.3°,I=22.9°(α_(95)=5.1°).特征剩磁分量在大约69%展开时获得最大集中,表明其为同褶皱重磁化;此时平均方向为D=339.1°,I=27.3°(α_(95)=4.1°),对应的古地磁极为65.4°N,327.5°E(A_(95)=3.5°),参考点29.3°N/88.5°E的古纬度为15.0°N±3.5°.薄片镜下分析显示赤铁矿为次生矿物,岩石磁组构(AMS)也表现为过渡型构造变形组构.样品的特征剩磁方向应为重磁化的结果,E/I(elongation vs inclination)校正法显示特征剩磁方向并没有发生倾角变浅.根据区域构造,重磁化时代约为72.4±1.8 Ma到64.4±0.6 Ma.综合考虑拉萨地块东西部的古地磁数据以及地震层析成像资料后我们认为,碰撞前拉萨地块大约呈NW-SE向准线性分布,并处于~10°N-15.0°N;自~70 Ma以来,拉萨地块与稳定欧亚大陆之间至少存在1200±400 km(11.1°±3.5°)的南北向构造缩短量;印度大陆与欧亚大陆的碰撞不应晚于55 Ma.     

塔里木柯坪塔格地区构造抬升的新证据——来自(U-Th)/He年龄的约束

柯坪塔格地区位于西南天山与塔里木盆地之间, 是塔里木地台的一部分, 其构造隆升与天山和塔里木盆地的演化密切相关. 本文首次将(U-Th)/He热定年技术应用于该地区构造抬升的研究, 对该区震旦系露头样品的磷灰石和锆石的(U-Th)/He进行了年龄测定和热史模拟, 结果表明柯坪塔格地区主要经历了4期构造抬升事件, 导致震旦系抬升至地表, 其中磷灰石(U-Th)/He年龄揭示了晚白垩世和中新世两期的构造抬升事件. 在早石炭世, 震旦系温度达到最大, 介于133~150°C之间, 结合沉积埋藏史得到当时的最大埋深是3400~3900 m. 在渐新世-中新世, 受印度-欧亚板块碰撞远程效应的影响, 柯坪塔格地区沿柯坪塔格-沙井子断裂向巴楚隆起上逆冲, 地层快速抬升遭受剥蚀. 在15~10 Ma时, 柯坪塔格地区震旦系已抬升至地表. 自早石炭世至今, 柯坪塔格地区总剥蚀量达6170 m. 柯坪塔格地区自中生代以来的构造-热演化史与塔里木盆地北缘是一致的, 但与天山及处于塔里木盆地内部的巴楚隆起的构造抬升过程存在差异. 中新世以后, 受喜山运动远程效应影响, 柯坪塔格和天山才同处于抬升状态; 而巴楚隆起在古近纪早期仍处于抬升剥蚀状态, 与柯坪塔格地区接受沉积相反. 本文利用(U-Th)/He热定年技术成功地揭示了柯坪塔格地区自震旦纪以来的构造-热演化史, 这些结果有利于人们对这一地区构造抬升的正确认识. 同时, 本研究对塔里木盆地的油气勘探及天山地区的构造研究具有指导意义.     

Mesozoic basin evolution and tectonic mechanism in Yanshan, China

The Mesozoic basins in Yanshan, China underwent several important tectonic transformations, including changes from a pre-Late Triassic marginal cratonic basin to a Late Triassic-Late Jurassic flexural basin and then to a late Late Jurassic-Early Cretaceous rift basin. In response to two violent intraplate deformation at Late Triassic and Late Jurassic, coarse fluvial depositional systems in Xingshikou and Tuchengzi Formations were deposited in front of thrust belts. Controlled by transform and extension faulting, fan deltas and lacustrine systems were deposited in Early Cretaceous basins. The composition of clastic debris in Late Triassic and Late Jurassic flexural basins respectively represents unroofing processes from Proterozoic to Archean and from early deposited, overlying pyroclastic rocks to basement rocks in provenance areas. Restored protobasins were gradually migrated toward nearly NEE to EW-trending from Early Jurassic to early Late Jurassic. The Early Cretaceous basins with a NNE-trending crossed over early-formed basins. The Early-Late Jurassic and Early Cretaceous basins were respectively controlled by different tectonic mechanisms.     

天山-帕米尔结合带的地壳速度结构及地震活动研究

利用流动地震台阵记录的地震数据,通过地震层析技术反演了天山—帕米尔结合带的P波速度结构,揭示出地壳结构的非均匀特征及其与地震活动的对应关系. 分析结果表明,天山和西昆仑的双向挤压导致塔里木西部边缘地壳严重变形,在山前地区形成基底隆起带,地壳深部则被断裂分割成为若干块体,有的块体可能卷入造山带内部;喀什坳陷地壳深部结构相对完整,变形程度较弱;天山和西昆仑的地壳结构显示出缩短增厚的波速特性,在与塔里木接壤的局部地区,壳幔边界附近存在热物质的侵入迹象. 大部分地震都发生在塔里木西部边缘的壳内高速块体周围,推测块体之间的相互作用和应力调整是导致天山—帕米尔结合带频繁发生地震的主要原因,伽师地震则与构造变形由天山向塔里木内部扩展以及该地区的地壳非均匀结构有关.     

FOCAL MECHANISM SOLUTION AND TECTONIC STRESS FIELD CHARACTERISTICS OF THE MIDDLE TIANSHAN MOUNTAINS,XINJIANG

The middle part of the Tianshan Mountains in Xinjiang is located in the north-central part of the Tianshan orogenic belt, between the rigid Tarim Basin and Junggar Basin. It is one of the regions with frequent deformation and strong earthquake activities. In this paper, 492 M_S>2.5 earthquake events recorded by Xinjiang seismograph network from 2009 to 2018 were collected. The M_S3.5 earthquake was taken as the boundary, the focal mechanism solutions of the earthquake events in this region were calculated by CAP method and FOCEMEC method respectively. At the same time the focal mechanism solutions of GCMT recorded historical earthquake events in this region were also collected. According to the global stress map classification standard, the moderate-strong earthquakes in the region are mainly dominated by thrust with a certain slip component, which are distributed near the combined belts of the Tarim Basin, Junggar Basin, Turpan Basin and Yili Basin with Tianshan Mountains. The thrust component decreases from south to north, while the strike-slip component increases. The spatial distribution characteristics of the tectonic stress field in the middle section of the Tianshan Mountains in Xinjiang are obtained by using the damped regional-scale stress field inversion method. The maximum principal compressive stress in axis the study area rotated in a fan shape from west to east, the NW direction in the western section gradually shifted to NE direction, its elevation angle is nearly horizontal, in the state of near horizontal compression. The minimum principal compressive stress axis is nearly EW, and the elevation angle is nearly vertical. Influenced by large fault zones such as Kashi River, Bolhinur, Nalati, Fukang, the southern margin of the Junggar and the north Beiluntai, the local regional stress field presents complex diversity. Under the influence of the northward extrusion of Pamir and Tarim blocks, the whole Tianshan is shortened by compression, but its shortening rate decreases from south to north and from west to east, the stress shape factor increases gradually from west to east, the intermediate principal compressive stress axis exhibits a change in compression to extension. There are some differences in the characteristics of tectonic stress field between the north and south of Tianshan Mountains. The regional maximum principal compressive stress axis is 15° north by east on the south side, while it is nearly NS on the north side. The deformation of the Tianshan Mountains and the two basins on both sides is obviously larger than that in the inside of the mountain. Changes in the crustal shortening rate caused by the rotation of the rigid Tarim block and Junggar block to the relatively soft Tianshan block, as well as the uplifts of Borokonu and Bogda Mountains, the comprehensive influence of the material westward expansion constitute the stress field distribution characteristics of the north and south sides of the middle section of Tianshan Mountains. The recent two M_S6.6 earthquakes in the region caused the regional stress field to rotate counterclockwise. The post-earthquake stress field and the main source focal mechanism solution tend to be consistent. The seismic activity in the study area is week in the south and strong in the north. The focal depth is about 20km. Most strike-slip earthquakes occur near the junction belt of the Tianshan and Junggar Basin.     

塔里木盆地古生代古地磁结果及其构造地质意义

发表了塔里木盆地奥陶纪、志留纪、泥盆纪、石炭纪、二叠纪古地磁新数据，大部分数据通过了剩磁分离或一致性检验、倒转检验、极性对比检验、褶皱检验和烘烤检验．根据新的数据绘制了塔里木板块古生代视磁极游移曲线（ＡＰＷＰ），探讨了塔里木板块构造演化规律，强调了奥陶纪末的加里东构造运动及早海西构造运动的重要意义．     

DETERMINATION OF TECTONIC EVOLUTION OF A SEDIMENTARY BASIN FROM SANDSTONE COMPONENTS

1 INTRODUCnONThe comPonents of terrigenous sedimenop rocks indicate not only provenance information, but alsotoctOnic evolution of basin. The chdrical composition of the soure rOCks is probaby the major conttDon the chendstry of sedimentny rocks although this can be greaily modified by subsequent Processes(Rollinson l993). Thus, through exndning Petrological and chendcal comPosihons of tenigenoussedlinmp rocks, the comPonentS of the provenance or somee rOCks - which are conunnly a fun…