Strike–slip origin of Cretaceous Mazhan Basin, Tan-Lu Fault Zone, Shandong, east China

The Mazhan Basin, Shandong Province, China, is located between the main faults, F₃ and F₄, of the Tan-Lu Fault Zone. It is an elongated basin more than 60 km in length and 8 km in width and contains a series of typical continental sediments (the Upper Cretaceous Wangshi Group). This series was divided into three sedimentary facies associations: conglomerate facies association; sandstone facies association of alluvial fan to lake margin environment; and siltstone facies association of lacustrine origins. Their zonal distribution pattern may represent a contemporaneous heterotopic facies due to a lateral facies change from margins to axis of the basin. Their stratigraphic sequence becomes younger northward along the boundary faults. This suggests that the depocenter of the fan–lake system tends to migrate northward along F₃. From the asymmetric features (i.e. basin shape, lithofacies distribution, facies change) the Mazhan Basin can be explained by progressive subsidence at the Tangwu releasing bend of F₃ with sinistral strike–slip movement. Judging from the fission track (FT) ages from the Wangshi Group, it was concluded that a sinistral strike–slip movement along the main fault, F₃ of the Tan-Lu Fault in Shandong, has lasted until the Late Cretaceous. Its displacement is estimated to be larger than the migrated distance, 60 km, of the depocenter of the Mazhan Basin.     

Late Cenozoic stress states around the Bolu Basin along the North Anatolian Fault, NW Turkey

This study defines the Late Cenozoic stress regimes acting around the Bolu Basin along the North Anatolian Fault in northwestern Turkey. The inferred regional stress regime, obtained from the inversion of measured fault-slip vectors as well as focal mechanism solutions, is significant and induces the right-lateral displacement of the North Anatolian Fault. The field observations have also revealed extensional structures in and around the Bolu Basin. These extensional structures can be interpreted as either a local effect of the regional transtensional stress regime or as the result of the interaction of the fault geometries of the dextral Duzce Fault and the southern escarpment of the North Anatolian Fault, bordering the Bolu Basin in the north and in the south, respectively.The inversion of slip vectors measured on fault planes indicates that a strike-slip stress regime with consistent NW- and NE-trending σ_Hmax(σ₁) and σ_Hmin(σ₃) axes is dominant. Stress ratio (R) values provided by inversion of slip vectors measured on both major and minor faults and field observations show significant variations of principal stress magnitudes within the strike-slip stress regime resulting in older transpression to younger transtension. These two stress states, producing dextral displacement along NAF, are coaxial with a consistent NE-trending σ₃ axis. The earthquake focal mechanism inversions confirm that the transtensional stress regime has continued into recent times, having identical horizontal stress axis directions, characterized by NW and NE-trending σ₁ and σ₃ axes, respectively. A locally consistent NE-trending extensional, normal faulting regime is also seen in the Bolu Basin. The stress-tensor change within the strike-slip stress regime can be explained by variations in horizontal stress magnitudes that probably occurred in Quaternary times as a result of the westward extrusion of the Anatolian block.     

Earthquake Triggering along the Xianshuihe Fault Zone of Western Sichuan,China

Western Sichuan is among the most seismically active regions in southwestern China and is characterized by frequent strong (M 6.5) earthquakes, mainly along the Xianshuihe fault zone. Historical and instrumental seismicity show a temporal pattern of active periods separated by inactive ones, while in space a remarkable epicenter migration has been observed. During the last active period starting in 1893, the sinistral strike–slip Xianshuihe fault of 350 km total length, was entirely broken with the epicenters of successive strong earthquakes migrating along its strike. This pattern is investigated by resolving changes of Coulomb failure function (CFF) since 1893 and hence the evolution of the stress field in the area during the last 110 years. Coulomb stress changes were calculated assuming that earthquakes can be modeled as static dislocations in an elastic halfspace, and taking into account both the coseismic slip in strong (M 6.5) earthquakes and the slow tectonic stress buildup associated with major fault segments. The stress change calculations were performed for faults of strike, dip, and rake appropriate to the strong events. We evaluate whether these stress changes brought a given strong earthquake closer to, or sent it farther from, failure. It was found that all strong earthquakes, and moreover, the majority of smaller events for which reliable fault plane solutions are available, have occurred on stress–enhanced fault segments providing a convincing case in which Coulomb stress modeling gives insight into the temporal and spatial manifestation of seismic activity. We extend the stress calculations to the year 2025 and provide an assessment for future seismic hazard by identifying the fault segments that are possible sites of future strong earthquakes.     

Late Paleozoic brachiopod faunas of the South Kitakami Belt, northeast Japan, and their paleobiogeographic and tectonic implications

Abstract    Late Paleozoic (Middle Devonian, Early Carboniferous and Middle Permian) brachiopod faunas of the South Kitakami Belt, northeast Japan, are closely related paleobiogeographically to those of the Xinjiang–Inner Mongolia–Jilin region, northwest–northeast China. This relationship suggests that the South Kitakami Belt was part of the trench or continental shelf bordering the northern and eastern margins of North China (Sino-Korea) during the Middle Devonian to Middle Permian times. Among the three models on the origin and tectonic development of the South Kitakami Belt, the strike–slip model is most consistent, but both the microcontinent model and the nappe model have considerable inconsistencies with the above paleobiogeographic and paleogeographic evidence.     

Late Mesozoic and Cenozoic wrench tectonics in eastern Australia: Insights from the North Pine Fault System (southeast Queensland)

The North Pine Fault System (NPFS) in SE Queensland belongs to a series of NNW-striking sinistral faults that displaced Paleozoic to Cenozoic rock units in eastern Australia. We have studied the geometry and kinematics of the NPFS by utilizing gridded aeromagnetic data, digital elevation models, and field observations. The results indicate that all segments of the NPFS were subjected to sinistral reverse strike-slip faulting. Restorations of displaced magnetic anomalies indicate sinistral offsets ranging from ∼3.4 to ∼8.2 km. The existence of a (possibly) Late Triassic granophyre dyke parallel to one of the fault segments, and the occurrence of NNW-striking steeply dipping strike-slip and normal faults in the Late Triassic-Early Cretaceous Maryborough Basin, indicate that the NPFS has likely been active during the Mesozoic. We propose that from Late Cretaceous to early Eocene, NNW-striking faults in eastern Australia, including the NPFS, were reactivated with oblique sinistral-normal kinematics in response to regional oblique extension associated with the opening of the Tasman and Coral Seas. This interpretation is consistent with the modeled dominant NNE- to NNW-directed horizontal tensional stress in the Eocene. The latest movements along the NPFS involved sinistral transpressional kinematics, which was possibly related to far-field contractional stresses from collisional tectonics at the eastern and northern boundaries of the Australian plate in the Cenozoic. This sinistral-reverse oblique kinematics of the NPFS in the Cenozoic is in line with ∼ESE to ENE orientations of the modeled maximum horizontal stress in SE Queensland.     

南海新生代海底扩张的构造演化模式: 来自高分辨率地球物理数据的新认识

根据高分辨率重、磁测网数据的分析,结合多波束海底地貌的构造解释,南海海盆新生代经历了两期不同动力特征的海底扩张,25 Ma的沉积-构造事件是其重要分界.早期扩张从约33.5 Ma开始至25 Ma停止,在东部海盆南、北两侧和西北海盆形成了具有近E-W向或NEE向磁条带的老洋壳,是近NNW-SSE向扩张的产物;晚期扩张从25 Ma开始至16.5 Ma结束,在东部海盆中央区和西南海盆形成了具有NE向磁条带的新洋壳,是NW-SE向扩张的产物.南海海盆分区特点明显,南北分区,东西分段.从南到北可进一步分为3个亚区,南、北亚区由早期扩张产生,而晚期扩张的中央亚区从东到西又可进一步分为6个洋段,中间均由NNW或NW向断裂分割,是扩张中脊分段性的表现.南海晚期扩张具有渐进式扩张的特点,虽然它们均于磁条带异常C5c停止扩张,但开始扩张的时间从东部的C6c(23.5 Ma),到中部的C6b(22.8 Ma),一直变新到西部的C5e(18.5 Ma).东部海盆与西南海盆之间的NNW向断裂是分割两海盆的边界断裂,不仅切割了磁条带异常,控制了两海盆不同的地球物理场特征,而且还使扩张中脊左行平移约95km,造成扩张中心和磁条带不连续.南海海盆扩张期间,其东部没有菲律宾群岛封闭,当时是一个面向大洋的港湾,与亚丁湾洋盆可以对比,是洋中脊向大陆边缘入侵的产物.     

Mechanisms of Cenozoic deformation in the Bohai Basin, Northeast China: Physical modelling and discussions

The Bohai Basin is a petroliferous Cenozoic basin in northeast China (Fig. 1(a)) and has apparent geo- metrical and kinematic similarities with the other Meso-Cenozoic extensional basins located along the eastern margin of the Eurasian Plate[1,2]. Its architec- ture and Cenozoic stratigraphy have been well under- stood from several decades of petroleum exploration. Previous studies have suggested that the Bohai Basinis a typical extensional basin and has two tectonic evolution phases, rift…     

Earthquake-induced soft-sediment deformation structures in the Mesoproterozoic Wumishan Formation,North China,and their geologic implications

Soft-sediment structures are key to defining seismites. Two soft-sediment deformation horizons, bounded by undeformed carbonate strata, have been found in the Wumishan Formation in the Jumahe region, 175 km southwest of Beijing. One is in the lowest part of Wumishan Formation; and the other is in the uppermost part of Litho-member I. The soft-sediment structures in these two horizons fall into three categories: mould-and-sag structures, hydraulic shatterings and liquefaction dikes. The mould-and-sag structures are divided into two types: one developed in tidal-flat sediments, accompa-nied by many liquefaction-related structures and characterized by autochthonous post-earthquake sediments in sags, and the other type developed in deep-water environments, is not associated with liquefaction structures, and is overlain immediately by seismogenic tsunamites. The hydraulic shat-terings are composed of pockets of fluidization conglomerate, sand intrusions, and syndepositional faults. The liquefaction dikes fall into two categories: hydraulic-fracturing dikes and lateral-spreading dikes. The former are steep, planar, and pinch out upwards. The latter are snake-like and characterized by no diapir-related drag structures in surrounding rocks. Examination of the attitudes and strati-graphic positions of these structures suggests that these soft-sediment structures are seismogenic, and consequently, are seismites. Most seismites in the Wumishan Formation are developed near the former western, margin fault of Yanliao rift. This occurrence suggests that they could be related to movements on this fault. Other geological implications are discussed.     

Late Holocene slip rate and average recurrence interval of great earthquakes on the Shangzhi segment of the Yilan‐Yitong Fault Zone,northeastern China: Constraints from paleo‐earthquakes and historical written records

The Yilan‐Yitong Fault Zone (YYFZ) is considered to be the key branch of the Tancheng‐Lujiang Fault Zone (TLFZ) in northeastern China. Although the Mesozoic and early Cenozoic deformation of the YYFZ has been studied intensively over the past century, few estimates of slip rate and recurrence interval of large earthquakes in the late Quaternary, which are the two most important parameters for understanding the potential seismic hazard of this crucial structure, were obtained. Based on integrated interpretations of high resolution satellite images and detailed geologic and geomorphic mapping, linear landforms were identified, including fault scarps and troughs, along the Shangzhi segment of the YYFZ, which exceeds 25 km in length. Synthesized results of trench excavations and differential GPS measurements of terrace surfaces indicate that two events (E1, E2) occurred along the Shangzhi segment during the late Holocene, which resulted in 3.2 ±0.1 m of total vertical co‐seismic displacement with clear features of thrust motion. ¹⁴C dating of samples suggests that event E1 occurred between 440 ±30 years BP and 180 ±30 years BP and that event E2 occurred between 4 090 ±30 years BP and 3 880 ±30 years BP, which indicates that the minimum vertical slip rate of the Shangzhi segment of the YYFZ has been approximately 0.8 ±0.03 mm/year during the late Holocene. Constraints from paleo events and the slip rate suggest that the average recurrence interval of major earthquakes on the YYFZ is 3 800 ±200 years. Historical documents in Korea show that event E1 possibly corresponds to the earthquake that occurred in AD 1810 (the Qing Dynasty in Chinese history) in the Ningguta area, which had surface‐wave magnitude (Ms) of 6.8–7.5. Studies of kinematics show that the right‐lateral strike‐slip with a reverse component has been dominant along the YYFZ during the late Holocene.     

基于重磁震资料的南海新生代盆地分布综合研究

作为西太平洋最大的边缘海,南海分布有30多个新生代沉积盆地,其蕴含着丰富的油气资源.但由于资料的限制,南海存在不同区域盆地研究程度不同,不同区域盆地面积差别较大,部分盆地只是坳陷而没有达到盆地的级别以及盆地外围可能存在凹陷等问题.南海新生代盆地分布问题制约了其油气分布规律、储量等基础地质问题的研究.本文以地震剖面数据为约束,以重力资料为主、辅以磁力资料,研究了南海新生代盆地分布及构造区划.通过提取新生代盆地及其构造单元引起的重力异常,结合地震剖面等资料反演了新生界底界面深度及新生界厚度.在充分调研已有盆地和构造单元划分方案的基础上,根据南海的地质及地球物理特征,确定了盆地及构造单元划分标准.以新生界厚度为基础并结合重、磁、震、地质等资料,进行地质-重磁震联合解释,将南海原有的36个盆地重新划分为24个盆地,盆地总面积扩大了约15万km2.研究表明,南海新生代盆地沉积层厚度在1.5~16 km之间,有6个北东东/北东向沉积坳陷带、2个近南北向沉积坳陷带以及1个三角沉积坳陷区;盆地展布方向主要为北东和北东东向,其次为北西和近南北向,呈现"南三北三"的分布特征.     

Accordant Summit Levels (ASLs) and Their Tectonic Deformation in the Denudational Areas of the North China Rift Zone

The North China rift zone,including the North China Plain rift zone and the middle Shanxi graben-rift zone,is a continental rift;geomorphologically,its most common and important characteristics are the multiple accordant summit levels (ASLs) in the denudational area.In this study three methods based on geomorphic analysis,that is,(1) unified topographic profiles,(2) cyclic knickpoints along longitudinal river profiles,and (3) depth contours of river downcutting,are used to identify the ASLs and analyze their tectonic deformation.The formation time of the ASLs is determined by geological and geomorphological evidence,the correlation with the sedimentary facies in the Plain rift zone,and K-Ar ages of basalts on the ASLs,indicating the rates of tectonic uplift.The North China rift zone has five ASLs,of which the highest and oldest ASL I is the remnant of a fossil peneplain formed before rifting and the other four lower and younger ones are pediplain-typed formed contemporaneously with rifting.Study of ASLs     

山东黄县弧形断裂带断层泥铁元素化学种分布特征及其地震地质意义

本文利用德国Wissel公司生产的新型穆斯堡尔谱仪(Bench-MB500)对山东龙口常庄子村北黄县弧形断裂断层剖面上的多种断层泥样品进行了穆斯堡尔谱测试分析,讨论了该断层剖面上铁元素地球化学分布特征及其地震地质意义。结果显示,该断裂中央部分比较年轻的断层泥相对富集para-Fe~(2+),而两侧较老的断层泥基本由para-Fe~(3+)组成;剖面断层泥样品中铁元素的地球化学特征与断层的活动演化历史密切相关,显示了断裂带内存在复杂的水岩相互作用。     

Occurrences of warm-adapted mammals in north China over the Quaternary Period and their paleoenvironmental significance

The north and south China faunas are subdivided along the line of Huaihe River-Qinling Mountains- Hengduan Mountains-Himalayas, to the north is the Palearctic Region, and to the south is the Oriental Region, which is the result of long-time evolution. Hundreds of Quaternary fossil localities have been known up to now, more than 60 of which contain warm-adapted elements which can be referred to 20 species. Among the warm-adapted elements appearing in north China, Hystrix, Macaca, Palaeoloxodon, Dicerorhinus and Bubalus are the most frequently recorded genera. There are three kinds of causal explanation about the frequent appearance of warm-adapted elements in north China: The first hy- pothesis attributed them to the dispersal events of warm-adapted mammals from the south during warm stages or warm seasons; the second scenario thinks that these warm-adapted mammals in north China were once derived there in situ and subsequently emigrated to the south with the cooling down of the global climate; the last hypothesis believes that these warm-adapted elements were not real warm-climate animals at that time. This study shows that almost none of the warm-adapted mammals in north China was recovered in the loess, and also almost all of the fossil localities which bear warm-adapted mammals fall within the warm temperate zone of nowadays. In fossil assemblage, those warm-adapted elements rarely co-exist with the cold-adapted mammals. All these evidences mentioned above indicate that the warm-adapted mammals in north China represent warm climate, but not hot one. Because all these warm-adapted mammals are widely distributed oriental elements, some of them even still exist north of the Huaihe River today. Up to now, no typical oriental elements have ever been re- covered in north China, such as pangolin, primitive primates (e.g. loris and tarsier), big apes (e.g. Gi- gantopithecus, Pongo and Hylobates), etc. The Late Pleistocene lasted a relatively shorter time, but the appearance of warm-adapted mammals during that span were the most frequent and most widespread. It means that the climate of the Late Pleistocene experienced the most frequent fluctuation over the whole period of Quaternary.     

Major element, trace element, and Sr, Nd and Pb isotope studies of Cenozoic basalts from the South China Sea

The whole rock K-Ar ages of basalts from the South China Sea basin vary from 3.8 to 7.9 Ma, which suggest that intra-plate volcanism after the cessation of spreading of the South China Sea (SCS) is comparable to that in adjacent regions around the SCS, i.e., Leiqiong Peninsula, northern margin of the SCS, Indochina block, and so on. Based on detailed petrographic studies, we selected many fresh ba-saltic rocks and measured their major element, trace element, and Sr-Nd-Pb isotope compositions. Geochemical characteristics of major element and trace element show that these basaltic rocks belong to alkali basalt magma series, and are similar to OIB-type basalt. The extent of partial melting of mantle rock in source region is very low, and magma may experience crystallization differentiation and cu-mulation during the ascent to or storing in the high-level magma chamber. Sr-Nd-Pb isotopic data of these basaltic rocks imply an inhomogeneous mantle below the South China Sea. The nature of magma origin has a two end-member mixing model, one is EM2 (Enriched Mantle 2) which may be originated from mantle plume, the other is DMM (Depleted MORB Mantle). Pb isotopic characteristics show the Dupal anomaly in the South China Sea, and combined with newly found Dupal anomaly at Gakkel ridge in Arctic Ocean, this implies that Dupal anomaly is not only limited to South Hemisphere. In variation diagrams among Sr, Nd and Pb, the origin nature of mantle below the SCS is similar to those below Leiqiong peninsula, northern margin of the SCS and Indochina peninsula, and is different from those below north and northeast China. This study provides geochemical constraints on Hainan mantle plume.     

西秦岭北缘断裂带西端晚第四纪活动特征及其西延问题

西秦岭北缘断裂是青藏高原东北缘的一条以左旋走滑运动为主的大型活动断裂。 通过卫片解译和野外地质调查, 认为断裂西端活动性仍很强烈, 并发现切龙沟一带全新世活动特征明显。 结果表明, 全新世以来西秦岭北缘断裂西端至少有2次古地震事件, 说明断裂经过土房村以后活动并没有停止, 而是继续向西延伸, 最后终止于甘加盆地。     

Texture and tectonic attribute of Cenozoic basin basement in the northern South China Sea

Based on the drilling data,the geological characteristics of the coast in South China,and the interpretation of the long seismic profiles covering the Pearl River Mouth Basin and southeastern Hainan Basin,the basin basement in the northern South China Sea is divided into four structural layers,namely,Pre-Sinian crystalline basement,Sinian-lower Paleozoic,upper Paleozoic,and Mesozoic structural layers.This paper discusses the distribution range and law and reveals the tectonic attribute of each structural layer.The Pre-Sinian crystalline basement is distributed in the northern South China Sea,which is linked to the Pre-Sinian crystalline basement of the Cathaysian Block and together they constitute a larger-scale continental block—the Cathaysian-northern South China Sea continental block.The Sinian-lower Paleozoic structural layer is distributed in the northern South China Sea,which is the natural extension of the Caledonian fold belt in South China to the sea area.The sediments are derived from southern East China Sea-Taiwan,Zhongsha-Xisha islands and Yunkai ancient uplifts,and some small basement uplifts.The Caledonian fold belt in the northern South China Sea is linked with that in South China and they constitute the wider fold belt.The upper Paleozoic structural layer is unevenly distributed in the northern South China.In the basement of Beibu Gulf Basin and southwestern Taiwan Basin,the structural layer is composed of the stable epicontinental sea deposit.The distribution areas in the Pearl River Mouth Basin and the southeastern Hainan Basin belong to ancient uplifts in the late Paleozoic,lacking the upper Paleozoic structural layers.The stratigraphic distribution and sedimentary environment in Middle-Late Jurassic to Cretaceous are characteristic of differentiation in the east and the west.The marine,paralic deposit is well developed in the basin basement of southwestern Taiwan but the volcanic activity is not obvious.The marine and paralic facies deposit is distributed in the eastern Pearl River Mouth Basin basement and the volcanic activity is stronger.The continental facies volcano-sediment in the Early Cretaceous is distributed in the basement of the western Pearl River Mouth Basin and Southeastern Hainan Basin.The Upper Cretaceous red continental facies clastic rocks are distributed in the Beibu Gulf Basin and Yinggehai Basin.The NE direction granitic volcanic-intrusive complex,volcano-sedimentary basin,fold and fault in Mesozoic basement have the similar temporal and spatial distribution,geological feature,and tectonic attribute with the coastal land in South China,and they belong to the same magma-deposition-tectonic system,which demonstrates that the late Mesozoic structural layer was formed in the background of active continental margin.Based on the analysis of basement structure and the study on tectonic attribute,the paleogeographic map of the basin basement in different periods in the northern South China Sea is compiled.     

Protolith ages and deformation mechanism of metamorphic rocks in the Zhangbaling uplift segment of the Tan-Lu Fault Zone

Protolith ages and Indosinian deformation mechanism of metamorphic rocks in the Zhangbaling uplift segment of the Tan-Lu Fault Zone are important, unsolved problems. Our LA-ICP-MS zircon dating work indicates that protolith ages of the greenschist-facies Zhangbaling Group are 754–753 Ma, and those of the amphibolite-facies Feidong Complex are 800–745 Ma. These rocks belong to the earliest cover of the Yangtze Plate. Their ages and metamorphic features suggest that the rocks did not come from the Dabie Orogen. The Indosinian structures in the Zhangbaling Group and lower Sinian strata formed in a flatlying ductile detachment zone with a shear sense of top-to-the-SSW whereas those in the underlying Feidong Complex are characterized by ENE-WSW inclined folds developed under a ductile regime. It is suggested therefore that the sinistral Tan-Lu Fault Zone of the Indosinian period is buried under the Hefei Basin west of the Zhangbaling uplift segment and the uplift segment is a displaced block neighboring the fault zone. Detachment deformation between the upper rigid and lower ductile crust during displacement of the Zhangbaling uplift segment resulted in the formation of the flat-lying ductile detachment zone and its underlying drag fold zone of a ductile regime. The protolith ages and deformation mechanism in the Zhangbaling uplift segment further prove sinistral origination of the Tan-Lu Fault Zone during the continent-continent collision of the North China and Yangtze plates and support the indentation model for the two-plate collision that considers the Tan-Lu Fault Zone as an oblique convergence boundary.     

郯庐断裂带合肥—宿迁段及邻区大地电磁三维成像

本文利用覆盖郯庐断裂带合肥—宿迁段及邻区的大地电磁阵列数据, 应用大地电磁三维反演技术和印模重构方法, 获得了测区可靠的三维电阻率模型.该电性模型中, 郯庐断裂带东西两侧在浅部均有高阻分布, 在深部电性结构显著不同, 具有西低东高的特征, 而郯庐断裂带则是两侧高低阻明显分界带; 在南北方向, 电性结构也存在较大不均匀性, 嘉山地区呈现低阻特征, 是断裂带上的电性分界点, 郯庐断裂带在此处由北部的四条主断裂变成南部的两条.结合研究区地质、大地测量和地震学等资料, 综合分析结果表明: 郯庐断裂带作为苏鲁造山带和张八岭隆起高阻体陡立的西边界, 切割深度超过莫霍面.嘉山地区相对低阻分割了张八岭高阻条带与苏鲁高阻体, 阻碍了断层上应力的传递, 造成了嘉山北、南两侧断裂带构造变形强、弱的变化, 从电性结构上证实了郯庐断裂带具有分段性的特征; 苏鲁高阻体南端向西偏转穿过郯庐断裂带, 阻碍断层滑动, 致使泗洪—嘉山段存在应力积累和断层闭锁的地震孕育环境, 其地震危险性值得关注.

     

中国东北地区北部上地幔各向异性及其动力学意义

中国东北地区广泛发育新生代板内火山,晚中生代以来岩石圈遭受过多期拉张作用.作为中国唯一的深震孕育区,中国东北地区受到太平洋板块的西向俯冲,使得其成为研究岩石圈变形、板块俯冲和板内火山成因及其相互作用关系的天然实验室.通过分析架设在中国东北地区北部的147个流动和固定台站的SKS波形数据,共计得到了377对各向异性参数和251个无效分裂结果.结果表明,中国东北地区东西两侧具有不同的各向异性分布:西部地区各向异性方向变化范围为N143-199°E,平均N169°E,与晚中生代岩石圈伸展方向一致;其各向异性延迟时间平均值约为0.8s,说明来自地幔的各向异性比较微弱,主要由残留在岩石圈中的古老变形所引起.同时,在松辽盆地和佳木斯地块部分区域,观测到延迟时间较小的各向异性(~0.4s),可能是由于岩石圈的拆沉和热地幔物质的上涌侵蚀了保留在岩石圈的古老形变所致.在研究区东部,NNW-SSE朝向的各向异性被观测到,并伴随较大的延迟时间(大于1.0s),可能与太平洋板块撕裂回撤而产生的地幔流动有关.此外,近W-E方向的各向异性只在佳木斯地块被观测到,而太平洋板块在地幔过渡带中的俯冲可能是其产生的主要成因.