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71.
由于工程需要,对广梧高速公路(马安—河口段)的地震地质情况进行了考察,马安—河口路段所处大地构造性质为东南地洼区,穿越了三个次级构造分区:白土断陷、思劳断隆、云浮断隆。路段附近发育3条断裂:肇庆断裂、河口断裂和吴川—四会断裂。前两者为非活动断裂,后者为活动断裂且星北东向从思劳附近穿过,是未来5.0级地震发生地段,烈度可达Ⅵ度。但路段附近地震活动水平较低,仅发生过4以—5.0级地震4次,最大烈度为Ⅴ度。白诸立交、河口立交的地震地质环境稳定,思劳立交基本稳定,沿线不易产生滑坡与崩塌。 相似文献
72.
Zhao Jinren Zhang Xiankang Zhang Chengke Ren Qingfang Cheng Shuangxi Zhang Jianshi Nie Wenying PAN Shuzhen 《中国地震研究》2003,17(2):103-112
The data from two deep seismic sounding profiles was processed and studied comprehensively. The results show that crnst-mantle structures in the investigated region obviously display layered characteristics and velocity structures and tectonic features have larger distinction in different geological structure blocks. The boundary interface C between the upper and lower crust and Moho fluctuate greatly. The shallowest depths of C (30.0km) and Moho (45.5km) under Jiashi deepen sharply from Jiashi to the western Kunlun mountain areas, where the depths of C and Moho are 44.0km and 70.0km, respectively. The higher velocity structures in the Tarim massif determine its relatively “stable“ characteristics in crust tectonics. The phenomenon in the Jiashi region, where the distribution of earthquake foci mostly range from 20kin to 40kin in depth, may infer that the local uplift of C and Moho interface, anomalonsly lower velocity bodies and deep large faults control earthquake occurrence and seismogenic processes in the Jiashi strong earthquake swarm. 相似文献
73.
A detailed investigation permitted us to obtain quantitative data concerning fine geometric structures of 4 faults of the active Maxianshan-Xinglongshan fault system and the latest movement along them. Of them the northern Maxianshan border fault is a large-scale, strongly active Holocene reverse sinistral strike-slip fault, the other 3 faults, the southern Maxianshan border fault and the southern Xinglongshan border and the northern Xinglongshan border faults are the accompanying active late-Pleistocene thrust faults, which are incorporated into the main strike-slip fault, the northern Maxianshan border fault at depth. It is the most important earthquake-controlling fault in the Lanzhou area, the fault influences and constrains the seismic activity in the area. 相似文献
74.
75.
滇西思茅大平掌矿区火山岩特征及其构造环境 总被引:3,自引:0,他引:3
滇西大平掌铜多金属矿床的含矿建造(龙洞河组)主要由细碧岩-角斑岩-石英角斑岩和流纹岩-硅质岩组成,伴有部分火山角砾岩、凝灰岩,属双峰式火山岩组合。火山岩具明显的Na2O>K2O和Nb、Ta、Zr、Hf、Ti亏损。岩石化学和微量元素判别标志指示含矿建造形成于岛弧裂陷环境。结合区域构造古地理资料分析,它是滇西南古特提斯洋壳在晚石炭世-早二叠世由西向东俯冲过程中岩浆作用的结果。 相似文献
76.
以大别造山带南部菖蒲地区为解剖区,结合区域地质调查分析,建立了包括浅变质岩层、超高压变质岩片在内的构造地层序列—岩片组合。对其组成特征、界面性质、形成时代、变形序列等,进行了较系统阐明,并对叠加褶皱型式及形成机制进行了讨论。 相似文献
77.
In Italy, the horizontal stress directions are well constrained in many regions, but the tectonic regime is not well known because the stress magnitudes are unknown. Our intention is to improve the knowledge of crustal stress in Italy, both at shallow depth and in low seismicity areas. Therefore, we inferred the tectonic regime from the comparison between the depth of breakout occurrence and the physical properties of the rocks in 20 boreholes. The critical value of the maximum horizontal stress, for which the effective tangential stress at the borehole wall overcomes the rock strength to form breakouts, could be computed from rock strength and density. Comparing the theoretical stress distributions for different tectonic regimes with the depth distribution of breakout occurrence, it is possible to infer the tectonic regime that fits best to the breakout depth distribution. We investigated boreholes up to 6 km deep located in different tectonic environments over the Italian peninsula: the Po Plain, the Apenninic chain, the Adriatic foredeep and the Tyrrhenian Quaternary volcanic region. These wells are characterised by breakout data of good quality (A, B and C, according to World Stress Map quality ranking system). The results are in general agreement with the style of faulting derived from earthquake focal mechanisms and other stress indicators. Our results show a predominance of a normal faulting (NF) regime in the inner Apennines and both normal faulting and strike–slip faulting (SS) style in the surrounding regions, possibly also associated with changes in the tectonic regime with depth. 相似文献
78.
Predictions from dynamic modelling of the lithospheric deformation are presented for Northern Europe, where several basins underwent inversion during the Late Cretaceous and Early Cenozoic and contemporary uplift and erosion of sediments occurred. In order to analyse the evolution of the continental lithosphere, the equations for the deformation of a continuum are solved numerically under thin sheet assumption for the lithosphere. The most important stress sources are assumed to be the Late Cretaceous Alpine tectonics; localized rheological heterogeneities can also affect local deformation and stress patterns. Present-day observations available in the studied region and coming from seismic structural interpretations and stress measurements have been used to constrain the model. Our modelling results show that lateral variation in lithospheric strength below the basin systems in Central Europe strongly controls the regional deformation and the stress regime. Furthermore, we have demonstrated that the geometry of the boundary between Baltica and Avalonia, together with different rheological characteristics of the two plates, had a crucial role on local crustal deformation and faulting regime resulting in the Baltica–Avalonia transition zone from the S–N Alpine convergence. 相似文献
79.
80.