A study of the depth of weathering and its relationship to the mechanical properties of near-surface rocks in the Mojave Desert     

Donald J. Stierman  John H. Healy 《Pure and Applied Geophysics》1984,122(2-4):425-439

Weathered granite extends 70 m deep at Hi Vista in the arid central Mojave Desert of southern California. The low strength of this granite is due to the alteration of biotite and chlorite montmorillonite. Deep weathering probably occurs in most granites, although we cannot rule out some anomalous mechanisms at Hi Vista. Geophysical instruments set in these slightly altered rocks are limited by the unstable behavior of the rocks. Thus, tectonic signals from instruments placed in shallow boreholes give vague results. Geophysical measurements of these weathered rocks resemble measurements of granitic rocks near major faults. The rheology of the rocks in which instruments are placed limits the useful sensitivity of the instruments.  相似文献   

The Earth's decelerated rotation and regularities in orientation of its surface lineaments and faults     

Lev A. Maslov  Vladimir A. Anokhin 《Planetary and Space Science》2006,54(2):216-218

The Earth's crust faults and lineaments group in clusters with predominant N-S and E-W (System I) and NW-SE and NE-SW (System II) directions. The earthquake epicenters of the Benioff seismofocal zones follow the same regularities. In other words, seismofocal zones (epicenters of earthquakes) constitute a part of the regular network of the Earth's crust and lithosphere faults and lineaments. Mathematical modeling of stress distribution in the lithosphere due to a change of the Earth's ellipsoid compression showed that the principal stresses σ₁ and σ₂ are oriented in N-S and E-W directions, while corresponding shear stresses τ are oriented in NE-SW and NW-SE directions. It is shown that the secular deceleration of the Earth's rotation can be a reasonable mechanism for the change of Earth's ellipsoid compression and, consequently, for the origin of the regular system of faults and lineaments described above.  相似文献   

大庆长垣南部白垩纪断裂活动及对浅层气藏的控制   总被引：2，自引：0，他引：2       下载免费PDF全文

李建民  付晓飞  玄昌姬  陆延平  刘海涛 《地质科学》2009,44(2):513-524

大庆长垣南部包括葡北、敖包塔和葡两3个局部构造.黑帝庙油层的形成与3种不同演化历史断层有关：反转期断裂（Ⅲ犁）、断陷期形成坳陷期和反转期均活动的断裂（Ⅰ-Ⅱ-Ⅲ型）和坳陷期形成反转期活动的断裂（Ⅱ-Ⅲ型）;其中连通气源岩且活动期与大量生排气期相匹配的Ⅰ-Ⅱ-Ⅲ型和Ⅱ-Ⅲ型断裂是生物气垂向运移的主要通道,Ⅰ-Ⅱ-Ⅲ型断裂是深部CO₂向上运移的主要通道.这些断层均是“似花状”断层组合的边界断层,对倾边界断层控制背斜和鼻状构造形成.数值模拟表明：对倾的气源断层与地层产状的配置关系共同控制天然气运移方向和聚集的部位,由于葡萄花和敖包塔构造西缓东陡,因此天然气主要富集在背斜东翼和背斜之间的断块上.  相似文献   

重磁三维反演伊犁盆地中部密度和磁性结构          下载免费PDF全文

索奎  张贵宾  梅岩辉  马勇胜 《地球物理学报》2018,61(8):3410-3419

伊犁盆地中部区域地处多个构造单元的交汇区,构造复杂,缺乏高精度地质资料,制约了对盆地构造演化的进一步认识.本文联合使用多种先验信息作为约束条件,利用高精度重磁数据反演获得了研究区地下海拔-10 km以浅的三维密度和磁性结构,增强了反演结果的可靠性.结果揭示以白石墩次凸为中心发育了一个"北断南超"的南西-北东向不对称型凹陷,北部沉积厚度大于南部;区内主要断裂具有高角度特征,生烃中心受断裂控制,阿吾拉勒山前凹陷浅部可能发育逆掩断裂;火成岩以侵入的基性火成岩为主,伴有部分喷出火成岩和中酸性火成岩.  相似文献   

Investigation on causes of the Siruyeh Landslide, West Semirom (Iran)     

M. Hashemi  A. Babaahmadi  R. Ajalloeian  H. Safaei  M. R. Rahnama 《Landslides》2009,6(2):101-109

The Siruyeh landslide occurred at the eastern side of the Siruyeh valley, 22 km west of Semirom city, south of Esfahān on 25th March, 2005 with large dimensions (2,400 m long, 450 m wide with total area of 1 km²). The sliding mass blocked the Siruyeh River making a 35-m-high natural dam and 6-acre lake 570,000 m³ in volume that poses a potential threat for the area. The landslide occurred in soil and intensely weathered marls of the Tarbur and Kashkan Formations (upper Cretaceous–Paleocene age). The overall comparison and interpretation of the gathered evidence from satellite images, field trips, and laboratory tests show that the most important factors involved in triggering the Siruyeh landslide in order of importance are heavy precipitation and snow melt and intense concentration of faults and fractures as well as weathered and weak lithology.  相似文献   

贝尔凹陷“源断势”对油成藏与分布的控制作用          下载免费PDF全文

付广  刘云燕 《地质科学》2011,46(4):1068-1078

为了研究贝尔凹陷源岩、断裂和势能场(简称“源断势”)控藏模式,采用油藏分布与源、断、势叠合方法,分别对油成藏、分布控制作用和控藏模式进行了研究,结果得到:1)南一段油源区控制着油藏形成与分布的范围;2)低势区控制着油聚集的部位;反向断裂翘倾隆起的低势区控制着南屯组和铜钵庙组油聚集成藏,反转构造低势区控制着大磨拐河组油聚...  相似文献   

Monitoring tectonic movements in the Simitli Graben, SW Bulgaria     

《Engineering Geology》2000,57(3-4):179-192

Long-term in situ monitoring of slow tectonic movements has been applied to a seismoactive region of SW Bulgaria, within the epicentral zone of one of the strongest earthquakes in Europe (4 April 1904, M=7.8). The region has been found the most seismoactive in Bulgaria being of interest to many scientists. Three spatial extensometers were installed here in carefully selected sites to reflect fault movements on fissures. The extensometer TM-71 used here, enables three-dimensional detecting of even very slow movements with the accuracy of 0.01 mm and high stability over time. After 17 years of measuring, the rates of tectonic movements were established at all three monitoring points. Movements recorded at point B6 located in the seismoactive Kroupnik fault zone are of a relatively high rate. Locally, they show left-lateral strike–slips at rates of ca. 2.7 mm year⁻¹, as well as thrusting with a mean rate of 1.9 mm year⁻¹. Monitoring point K7 located in a fissure of the same zone on a steep slope affected by recent earthquakes has shown an uplift tendency of the block W of the Strouma Fault, with a result of gradual slope subsidence occurring from time to time. Monitoring point K5 located in a fissure of Strouma Fault zone became increasingly active during the last 2 years after 8 years of relative quiescence. Before that, only low left-lateral movements could be observed. Long-term fissure monitoring has shown quite a number of details interpretable to the dynamics of a broad region. Permanent shear displacements were found to develop after earthquakes. It was established that only a certain distinct part of local earthquakes provide such a displacement reaction at the monitoring points showing particular seismic connections.  相似文献   

Glossary of fault and other fracture networks     

《Journal of Structural Geology》2016

Increased interest in the two- and three-dimensional geometries and development of faults and other types of fractures in rock has led to an increasingly bewildering terminology. Here we give definitions for the geometric, topological, kinematic and mechanical relationships between geological faults and other types of fractures, focussing on how they relate to form networks.  相似文献   

What do fault patterns reveal about the latest phase of extension within the Northern Snake Range metamorphic core complex,Nevada, USA?     

《Journal of Structural Geology》2016

The Northern Snake Range is a classic example of a metamorphic core complex, Basin-and-Range province, United States. It is composed of a plastically deformed footwall and a brittlely deformed hanging wall, separated by the Northern Snake Range low-angle detachment (NSRD). Brittle deformation, however, is not confined to the hanging wall.This paper focuses on exposures in Cove Canyon, located on the SE flank of the Northern Snake Range, where penetrative, homogeneous faults are well exposed throughout the hanging wall, footwall and NSRD, and overprint early plastic deformation. These late-stage fault sets assisted Eocene-Miocene extension. Detailed analysis of the faults reveals the following: (1) The shortening direction defined by faults is similar to the shortening direction defined by the stretching lineation in the footwall mylonites, indicating that the extensional kinematic history remained unchanged as the rocks were uplifted into the elastico-frictional regime. (2) After ∼17 Ma, extension may have continued entirely within elastic-frictional regime via cataclastic flow. (3) This latest deformation phase may have been accommodated by a single, continuous event. (3) Faults within NSRD boudins indicate that deformation within the detachment zone was non-coaxial during the latest phase of extension.  相似文献   

Structural control on the shape of intrusions in the Koktokay ore district,Chinese Altai,north western China     

《Journal of Structural Geology》2016

The Koktokay pegmatite-type rare-metal-bearing ore district in the Altai orogen is famous for both its large scale and its diversity of rare metals. However, the emplacement mechanisms of the ore-bearing pegmatite intrusions in the Koktokay ore district are still unclear. Based on field observations, the emplacement of the ore-bearing pegmatite intrusions falls into two types. The first type is typical of the formation of dykes and sills, whereby they intruded into fan shaped, moderate dipping, joints within plutonic rocks. The second type involves the formation of a punched laccolith that was fed by a pegmatite sill. Magmatic stoping is the main mechanism of the laccolith emplacement. The peripheral faults played an important role in helping the emplacement of the laccolith. The trend of dykes and sills indicate two potential prospecting areas, which are located in the western and northern regions of the Koktokay ore district.  相似文献