Multiple episodes of tectonothermal processes in the Eastern Ghats granulite belt

A suite of rocks from Borra Carbonate Granulite Complex (BCGC) in the Eastern Ghats granulite belt displays superposed structures and overprinted mineral assemblages that reveal multiple episodes of tectonothermal reworking of the complex under granulite facies condition. Five distinct episodes of deformation (D₁, D₂, D₃, D₄ and D₅) and four phases of metamorphism (M₁, M₂, M₃ and M₄) are recorded. The signature of the earliest tectonothermal event, D₁ is a gneissic foliation (S₁) denned by segregation of peak granulite facies mineral assemblages corresponding to prograde M₁ metamorphism. M₂ metamorphic overprint represents an episode of near-isobaric cooling of the complex under a static condition. D₂ represents an episode of ductile deformation manifested by isoclinal folding (F₂) and associated extensional structures, within a broad framework of coaxial bulk deformation. The present study reveals that D₂ took place subsequent to M₂ - Subsequent deformation, D₃, produced F₃ folds and also deformations of boudins formed during D₂. M₃, which is synchronous with F₃, represents a near isothermal decompression of the BCGC. This was followed by a weak structural readjustment (D₄), producing E-W cross folds. The latter was not, however, associated with any recognizable petrological reworking. In the terminal events, deformation (D₅) and mineral reactions (M₄) were localized along narrow intersecting shear zones. The latter acted as channelways for carbonic and still later hydrous fluid infiltration. The available thermobarometric data from BCGC and other areas of the Eastern Ghats belt reveal that reworking during M₂ and M₃ ensued in a thermally perturbed regime. The high thermal regime might also have persisted during carbonic fluid infiltration related to terminal reworking (M₄).     

造山带岩浆活动与构造运动关系研究综述

熔体及其活动在造山带的演化中发挥了重要作用。熔体活动发迹了地壳应力作用方式而诱发形成剪切带或断层；熔体活动调整块体间的位移而影响造山带的变形；     

由震源机制和地震波各向异性探讨青藏高原岩石圈变形

本文据青藏高原天然地震震源参数和地震波各向异性资料，讨论了高原岩圈不同圈层的变形特性。     

米山断裂构造变形特征及其意义

米山断裂是一多期变形断裂，早期以韧性变形为主，后期以脆性变形为主，断裂变形具有准对称性，西盘变形强度大于东盘。变形强度决定了断裂带的蚀变及矿化特点，蚀变的分带结构与断裂的不同矿化特征都与断裂的变形有关，因此米山断裂的生成与发展，对胶东东部的成岩成矿具有重要作用，它控制了燕山早期花岗岩的侵入，韧性变形作用是金矿成矿的必要条件。     

昆仑山口西MＳ＝8．1级地震的形变应变场研究

根据昆仑山口西8．1级地震前后GPS测点的位移速率，用弹性模型公式计算了地壳应变参数．应变参量的变化表明，震前在地震区附近以压应变为主，应变速率较大．位移速率矢量显示出震前的震中地区相对周围为活动性较弱的“稳定”地区．地壳的形变和应变揭示出孕震体在挤压状态下积累了较高的应变势能．8．1级地震的同时期由于地壳释放了巨大的应变能而应变速率变化显著．计算结果表明，地震所产生的应变达到4．5×10-6以上．发震断裂带的平均左旋走滑量是3．31m（89°E～96°E）．     

2001年昆仑山口西8.1级地震同震形变场特征的初步分析a

利用差分干涉雷达测量技术获取的宏观震中区的同震形变场，结合对地震活动性、震源机制、野外考察等资料分析，对昆仑山口西8.1级地震同震形变场特征进行了研究. 结果表明:宏观震中位于库赛湖东北侧，宏观震中区发震断层可分为两个形变中心区域，其中西段长约42 km，东段长约48 km，整个发震断层主破裂段长90 km；由干涉形变条纹分布格局可清楚地判断出发震断层的左旋走滑特征；断层两盘变形特征不同，南盘变形程度明显大于北盘；宏观震中附近最大斜距向位移量为288.4 cm，最小斜距向位移量为224.0 cm，宏观震中发震断层最大左旋水平位错为738.1 cm，最小地面左旋水平位错为551.8 cm.      

安徽淮河构造变形带及邻近块体现代构造应力场特征

针对安徽省较特殊的构造环境及历史地震分布特点，利用直达波最大振幅比和系统聚类分析方法，在对安徽淮河中游区1974年以来近百个中小地震震源机制反演、聚类及空间合成的基础上，分析了华北断块南缘的安徽淮河构造变形带及邻近块体震源断层滑动方式、构造应力场分布及块体运动方式、应力场随时间变化等。结果显示：淮河构造变形带及其邻近块体上震源断层总体上以近走滑型或斜滑型破裂为主，但倾滑型破裂也占一定比例；该地区构造应力以水平作用为主，但也存在一定的垂向作用。其中淮北和皖中块体仍可能分别向SWW和NEE方向运动，并在淮河构造变形带上产生左旋剪切作用，呈现一定的继承性活动特征；各块(带)上主压应力P轴走向随时间的变化在总体上较为一致，而各时段之间P轴方位存在一定差异，显示安徽淮河中游区受华北和华南应力场的共同作用，但其地震活动可能主要受控于华北应力场。     

全球定位系统GPS技术及其在地球动力学方面的应用

本文简述了GPS测量技术 ,重点介绍了福建地壳形变GPS观测网利用GPS定位技术在地壳形变监测方面及其在地球动力学方面的应用 ,并取得了有重要意义的科学成果。     

红层软岩隧洞围岩变形破坏机制研究

红层软岩的物质组成、化学成分、物理力学性质等方面在国内外已有较系统的研究,但对软岩隧道围岩的变形破坏机理及其治理一直是工程技术人员关心问题。通过对回龙宫隧洞的地质环境分析及有限元数值计算,阐明了红层隧洞围岩的膨胀变形破坏机理,最后提出了在此类围岩中修建水工隧洞的过程中,防止围岩变形破坏的建议。     

CHARACTERIZATION OF DEFORMATION AND X-RAY PETROFABRICS IN THE MIDDLE PART OF THE WAHONGSHAN FAULT ZONE, QINGHAI PROVINCE, NORTHWESTERN CHINA

The Wahongshan fault zone in Qinghai province is one of the most important faults in westem China. In this paper, deformation and X-ray petrofabrics have been studied in the middle segment of the fault. The results show that the formation of the fault zones can be divided into two major stages: ductile shear deformation stage and brittle deformation stage. The early stage ductile shearing leads to the formation of the NW-NNW trending mylonite zones along the fault, which is intensely cut by the late-formed brittle faults. X-ray petrofabrics of rocks near the faults indicate that the minerals in the tectonites show a great degree of orientation in the alignment. The quartz, which is a very important mineral in the tectonites, is deformed by basal face gliding or near basal face gliding, and sometimes by prismatic face sliding, which indicates that the rocks are deformed in epithermal to mesothermal or mesothermal environment, and the dynamic recrystallization also plays an important role in the formation