内蒙古北山地区阿民乌素蛇绿岩的年代学、地球化学特征及大地构造意义     

孟庆涛 《地质与勘探》2021,57(1):122-135

内蒙古北山地区阿民乌素蛇绿岩是芨芨台子-小黄山蛇绿岩带的重要组成部分,主要由变质辉长岩和极少强蛇纹石化橄榄岩组成。变质辉长岩LA-ICP-MS锆石U-Pb年龄453±12 Ma,形成于晚奥陶世。强蛇纹石化橄榄岩MgO(36.90%~37.44%)、Ni(1980×10^-6~2232×10^-6)、Cr(2312×10^-6~2506×10^-6)含量高,而Al2O3(0.59%~1.41%)、TiO 2(0.01%~0.02%)和∑REE(0.85×10^-6~3.25×10^-6)含量低,具亏损地幔岩特征;变质辉长岩MgO(7.22.20%~11.66%)相对含量高;Al2O3(15.61%~18.79%)、TiO 2(0.20%~0.29%)、P2O5(0.01%)、K2O+Na2O(1.36%~2.43%)含量低,且K2O相似文献   

活动断裂带岩石的变形机制和摩擦性质—以圣·安德列斯断层为例     

金田龙  王勤 《江苏地质》2021,45(4):375-383

岩石的变形机制和力学性质对认识活动断裂带的孕震机制和发震过程都具有重要意义。圣·安德列斯（San Andreas）转换断层是太平洋板块与北美板块的构造边界,也是重要的地震活动带,总结了美国南加州地震中心对圣·安德列斯断层钻孔断层岩的研究进展。对断层泥的高速摩擦实验发现：动力弱化现象只在高速滑移时才发生,伴随着摩擦生热,岩石的摩擦系数显著降低。断层泥中富镁黏土矿物的富集可以显著降低断层的摩擦系数,促进蠕滑,黏土矿物的不均一分布可导致断裂带变形行为和地震分布的突变。与断层泥和碎裂岩不同,粉碎岩形成于快速传播地震的断裂端部,具高孔隙率和高渗透率,流体活动性强。此外,断层岩的有机质成熟度可用来追溯古地震造成的热异常。在川滇中国地震科学实验场开展科学钻探项目,研究断层岩样品的显微结构、物理性质和变形历史,以期为理解大陆汇聚与转换挤压过程中复杂的地震活动提供重要信息。  相似文献   

黄河口水下斜坡波致圆弧振荡剪切破坏分析   总被引：2，自引：2，他引：0  

常方强  贾永刚 《海洋学报》2010,32(5):175-179

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Relationship between rank and distribution of methylaromatic hydrocarbons for condensates of different origins     

P. Garrigues  J. Connan  E. Parlanti  J. Bellocq  M. Ewald 《Organic Geochemistry》1988,13(4-6)

Aromatic hydrocarbon fractions from thirty gas condensates have been analysed by capillary GC and high resolution Shpol'skii spectroscopy for the determination of the relative distribution in methylphenanthrene (MP), dimethylphenanthrene (DMP) and methylpyrene (MPy) series. The measured maturity indices, MPI, DMPI and MPyI which appeared previously suitable for rocks, coals and crude oils have been tested for the recognition of rank levels of condensates. MPI and DMPI exhibit a remarkedly similar evolution which allows the differentiation of the samples analysed in these works. Such studies extend the applicability of alkylaromatic hydrocarbon ratios to the characterization of maturity level of condensates which range from immature-marginally mature to overmature samples, partially biodegraded or not.  相似文献   

The control of maturity and kerogen type on quantitative analytical pyrolysis data     

Kjell ygard  Steve Larter  Joe Senftle 《Organic Geochemistry》1988,13(4-6)

Quantitative pyrolysis-gas chromatography has been performed on 96 kerogen samples isolated from 17 wells on the Norwegian Continental shelf. Petrographic and bulk geochemical measurements were also performed on the samples, and a combined data set of 117 variables for each sample was analysed using principal components analysis (PCA). This approach provides an objective and reproducible means of kerogen characterisation, which can be easily automated. In addition to objective kerogen characterisation and facile visualisation of facies and maturity related chemical trends, the method has the potential to allow objective prediction of key geochemical parameters such as maturity level from pyrogram data.  相似文献   

An unusual zone of seismic coupling in the Bonin arc: The 1972 Hachijo-Oki earthquakes and related seismicity     

Tetsuji Moriyama  Fumiko Tajima  Tetsuzo Seno 《Pure and Applied Geophysics》1989,129(1-2):233-261

The 1972 February and December Hachijo-Oki earthquakes (M _s=7.3 and 7.4), in the northernmost part of the Izu-Bonin subduction zone, are the only major events (M _s>7.0) in the Bonin arc for the past 80 years. Relocation of the hypocenters, using one smaller event having a wellconstrained focal depth as a master event, shows that the depth of the February event is 10 km shallower than that of the December event. We have determined the rupture process for both events by minimizing the error in waveform between observed and synthetic seismograms. Although the number of available stations are limited, the depth range of the major energy release for the December event extends deeper than for the February one. The rupture propagated up-dip for both events. It is likely that the rupture zone of the two events overlapped, and that the December event ruptured the deeper part. This suggestion is consistent with the observation that the aftershock zones of both events overlap with that of the December event shifted landward. The waveforms of the December event have a smaller high frequency component than those of the February event, suggesting that the stress at the thrust zone became more uniform or reduced after the February event.No thrust type smaller event occurred near the rupture zone. Instead, theP-axes of smaller events are parallel to the dip of the slab and theirT-axes dip to the southwest. Focal depths of these events estimated byP-wave forward modeling are generally between 40–50 km and located beneath the thrust zone. We thus interpret them as the events within the Pacific slab near the zone ruptured by the two major events. The stress concentration around the rupture zone of the major events is suggested to have triggered these slab events. After the occurrence of the large events, the slab events are concentrated near the deeper portion of the rupture zone. These events may have been caused by the loading of the down-dip compressional stress near the down-dip end of the rupture zone due to the rupture. The occurrence of the doublet of large earthquakes and a number of down-dip compressional events beneath their rupture zones in a shallow portion of the subducting slab indicates an unusual zone of seismic coupling in the Bonin arc, most of which is seismically quiescent.  相似文献   

喜马拉雅山南部的构造复杂性          下载免费PDF全文

秦建业 《地球物理学报》1988,31(4):410-419

根据对恒河盆地西部的多振型宽频带面波频散资料的分析推断,该区的地壳结构不具有大陆地盾的特征,相反,却非常象某些海洋高地。这一异常的海洋型地壳与恒河盆地东部地盾地壳的分界线可能在阿拉瓦利山脉（Aravalli Ridge）。该处地壳的地质特征具有异常高的电导率,其走向垂直于喜马拉雅山脉。目前广为接受的假定认为是构造均匀的印度大陆岩石圈向喜马拉雅山下俯冲。本文的研究结果对此观点提出了置疑:在北部印度大陆内的地壳运动可能存在着差异。我们追溯印度-欧亚大陆的碰撞历史,这个因素恐怕是不容忽视的。  相似文献   

广西弧形构造探讨     

褚有龙 《地球科学》1988,(6)

广西构造实为一弧形构造,它由四个并排的北东—北西向的轭状弧带所组成。每个弧带的前部,为坚硬的岩块所组成,所产生的断裂及岩浆活动对寻找与火成岩有关的矿产有一定意义。每个弧带的后部,产生盆地型沉积,有利于沉积矿产的形成。  相似文献   

求解非线性有限元方程的弧长法及在工程稳定分析中的应用   总被引：1，自引：0，他引：1  

刘国明  卓家寿 《岩土力学》1993,14(4):57-67

本文讨论了求解非线性有限元方程弧长法的基本原理及具体实施,并应用于压杆及滑块的稳定性分析。由于弧长法具有确定并通过结构临界应力状态的临界荷载值,因此可以应用于工程稳定性分析。算例表明,弧长法确定的临界荷载值是令人满意的。  相似文献   

吉林省中,新生代陆缘弧发展演化阶段及其类型划分     

孙永波 《吉林地质》1995,14(1):57-63

依吉林省中，新生代陆缘弧发展演化特征，将其划分为三个发展演化阶段，即陆缘弧隆断阶段（Ｔ３－Ｋ１）陆缘弧隆拗阶段（Ｋ２－Ｋ２）和陆缘弧裂解阶段（Ｅ－Ｑ）。根据陆缘弧发展演化过程中的性状变化特点，陆缘弧类型可相应地划分在挤压型陆缘弧，盆岭型陆缘弧和裂解型陆缘弧。  相似文献