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1.
This study is an attempt to clarify the subsurface geological settings at Abu Darag area in the N part of the Gulf of Suez through the analysis of the available seismic data. The time contour maps of three different reflectors (Top Kareem, Within Rudeis and Top Nukhul) present in this area were constructed and several structures were detected. Generally, the area is considered as a tilted fault block dipping in NE-SW direction and it is dissected by different faults. Major and minor NW-SE faults are the strongest trend in the area while other fault trends are with very weak magnitude and limited extent. All these fault trends restrict between them some high and low areas. Also, two geo-seismic sections were built to confirm the structural prospects on Top Nukhul time contour map. 相似文献
2.
Lineament maps based on Landsat, geological and aeromagnetic data on land, and aeromagnetic, gravity and seismic reflection data at sea have been studied to determine the main lineament trends on land and off-shore in southern Norway.On land there are three main structural trends (NE-SW, NW-SE and N-S) as well as a fourth, weaker trend (E-W). These four trends are thought to represent fracture patterns of Precambrian age.In the off-shore part of the study area, the same four trends are shown by the aeromagnetic data. (The gravity data yield unsatisfactory results for which the reasons are given.) It is therefore concluded that the same type of crystalline basement that is exposed on land also underlies the off-shore area.It is argued that these Precambrian structural trends have also pre-determined lines of weakness in Phanerozoic times. Fracture sets in the Norwegian Caledonides may provide an example of large-scale re-activation of the NE-SW structural trend, and the Viking and Oslo Grabens of the re-activation of the N-S trend.On a smaller scale, and in the off-shore part of the study area, it is likely that a re-activation of the NE-SW structural trend has played a role in the formation of the Ling Graben, the NW-SE trend in the origin of the Sele and Flekkefjord Highs, the N-S trend in the formation of the Lista Nose, and the E-W trend in the formation of the Farsund Sub-basin. 相似文献
3.
M. Sridhar A. Markandeyulu A. S. Chawla A. K. Chaturvedi 《Journal of the Geological Society of India》2018,91(2):165-173
Aeromagnetic data overcome constrain of inadequate exposures and provide signatures of bodies beneath sediment cover. Present work on analysis of aeromagnetic data over western part of Kaladgi basin provided insight into the basement structures and their role in basin evolution. In the study area, the NW-SE and NE-SW are the major trends of magnetic lineament followed by E-W and N-S trends.Archean to Paleoproterozoic basement is manifested by two structural zones, NW-SE trends related to major lineaments within the basement and the NE-SW trends presumed intra-basinal fault systems which controlled the local depressions. The basin configuration deduced from depth to basement show that the Kaladgi basin is an open deep basin and divided into several sub-basins, separated by fault-controlled NE-SW and NW-SE oriented basement ridges. An intriguing find in the western part are the numerous scattered smaller-scale, circular or semicircular, distinct magnetic anomalies of moderate to strong magnetic signal with strong remenance. Analyses coupled with 3D inversions in combination with sub-surface probing reveal in-homogeneities within basement gneisses and supracrustal rocks of the Kaladgi basin, Dharwar craton. 3D inversions of these circular bodies, suggest that they are apophyses of the intrusions or alternatively as younger intrusive stocks. Sub-surface probing by boreholes over circular bodies revealed leucocratic granite with porphyritic texture emplaced as intrusive within the Chitradurga metasediments. This implies that these intrusives are post-Chitradurga schist and pre Badami sediments as they have not affected the latter. However, they can be presumed to be coeval to potassic granites, which intrude the eastern part of the western Dharwar craton in southern India, until geochronological data are available. 相似文献
4.
Reliable fault plane solutions of shallow earthquakes and information on surface fault traces in combination with other seismic, geomorphological and geological information have been used to determine the orientation and other properties of the seismic faults in the Aegean and surrounding area.Thrust faults having an about NW-SE strike occur in the outer seismic zone along western Albania-westernmost part of mainland of Greece-Ionian Sea-south of Crete-south of Rhodes.The inner part of the area is dominated by strike-slip and normal faulting. Strike-slip with an about NE-SW slip direction occurs in the inner part of the Hellenic arc along the line Peloponnesus-Cyclades-Dodecanese-southwest Turkey as well as along a zone which is associated with the northern Aegean trough and the northwesternmost part of Anatolia. All other regions in the inner part of the area are characterized by normal faulting. The slip direction of the normal faults has an about SW-NE direction in Crete (N38°E) and an about E-W direction (N81°E) in a zone which trends N-S in eastern Albania and its extension to western mainland of Greece. In all other regions (central Greece-southern Yugoslavia and Bulgaria, western Turkey) the slip of the normal faults has an about N-S direction. 相似文献
5.
以渤海湾地区Z油田沙一下生物灰岩油藏为例, 利用岩心、薄片及成像测井等资料, 对天然裂缝特征及控制因素进行研究, 并对裂缝的成因机理进行了分析.研究表明, Z油田沙一下生物灰岩储层主要发育构造裂缝及成岩裂缝两种类型, 其中构造裂缝又分为剪切裂缝及扩张裂缝两类; 大多数构造裂缝为高角度缝, 主要方位为北东-南西向、北西-南东向及近东西向; 裂缝纵向高度一般小于170 cm, 裂缝平面长度主要分布在35 m以内, 裂缝开度主要在100 μm以内; 裂缝的发育受岩性、岩层厚度、断层等地质因素控制.该区构造裂缝主要在始新世-渐新世裂陷中后期北西-南东向引张应力场及东营末期北东东-南西西向反转挤压应力场两期构造应力作用下形成, 其中早期主要形成北东-南西向的正断层型裂缝, 晚期主要形成北东-南西向、北西-南东向的剪切裂缝及近东西向扩张裂缝. 相似文献
6.
太行山隆起南段新构造变形过程研究 总被引：9，自引：0，他引：9
基于TM遥感影像解译和断裂滑动矢量资料的野外观测,结合年轻地质体热同位素和放射性同位素年代学测试结果分析,重点描述了太行山隆起南段构造地貌特征,划分了新构造变形阶段,确定了新构造应力场及其转换历史。研究表明,新近纪以来,太行山南段经历了两期重要的引张变形时期。中新世中晚期,伴随华北地区广泛的基性火山喷溢活动,太行山南段受近NE-SW向引张应力作用,构造变形集中在南段东缘和南缘断裂带上。上新世至早更新世时期,强烈的NW-SE向地壳引张导致太行山隆起南段夷平地貌的解体和地堑盆地的形成。自中晚更新世以来,太行山南缘断裂带成为新构造变形的主要边界带。断面滑动矢量分析和山前年轻冲积扇体和小冲沟沿断裂错移特征分析,表明太行山南缘断裂带是一条斜张左旋走滑边界断裂带,引张方向为NW-SE至NNW-SSE.从区域大地构造角度,中新世中国东部NE-SW向拉伸作用与东部太平洋板块向西俯仲导致的弧后扩张动力过程有关;而上新世以来新构造变形是与青藏高原快速隆升及其向东构造挤出作用有关。 相似文献
7.
SummaryA Geodynamic Study of Peninsular India An attempt was made to elucidate the geodynamic conditions existing at the present time in Peninsular India. Morphological, structural and seismic information was collected for this purpose, as well as data from in-situ stress measurements by the hydraulic fracturing method. Inasmuch as the seismic activity was mainly concentrated around Koyna, the latter region was especially scrutinized. It has been found that the morphological (valley trends), structural (joint orientations) and seismic (fault plane solutions of earthquakes) evidence are all consistent with a neotectonic stress field whose maximum compression acts horizontally NW-SE, and whose minimum compression acts horizontally NE-SW. This trend is also confirmed by data from in-situ stress measurements in the Kolar Gold Fields. The lineaments gleaned from landsat imageries do not fit this pattern, indicating that they may not be related to the neotectonic conditions existing in India at all.With 30 Figures 相似文献
8.
R. Ananda Reddy 《Journal of the Geological Society of India》2014,83(3):235-251
Widespread distribution of mafic dykes and scanty occurrence of ultrabasic intrusives of kimberlitic affinity around Proterozoic Cuddapah basin, parts of Eastern Dharwar craton of south India has been the focus of attention since their discovery, to understand the structural fabric in relation to their emplacement in geological time. Satellite Imagery, geomorphological, geophysical and radiometric age data of Narayanpet area, northwest of Cuddappah basin, have clearly displayed the alignments and structures of geological significance, such as deep seated fault / fracture / shear zones, stratigraphic / lithological contacts, basic / ultrabasic intrusives and younger granites etc,. Based on the field observations such as emplacement of mafic dykes, their cross cutting relationship, study of morphological and geophysical signatures, inferred linears drawn from satellite imagery, aeromagnetic and gravity maps are arranged in a chronological order. A system of long, narrow and widely spaced dykes trending NW-SE direction conformable to gneissic foliation, typically associated with migmatites in the southwestern part of the study area are the oldest. Followed by E-W dykes, cut across by the sparsely distributed dykes associated with NW-SE and N-S features and in turn off set by dykes of NE-SW trends are the youngest. Kimberlites of Narayanpet area, belongs to hypabysal facies, which are essentially controlled by E-W to ENE-WSW deep seated fault / fracture zone, their intersection with NW-SE, NE-SW to N-S trends, which may have been reactivated during Proterozoic period as indicated by the intrusion of mafic dykes (～2270 to 1701 Ma) and emplacement of kimberlitic magmatism (～1300 to 1100 Ma) suggesting different intrusive episodes. Kimberlite pipes of Narayanpet field, falls in an ellipsoid form trending WNW-ESE direction in the northern part of the area, associated with radial drainage / topographic high and a gravity low. In addition, physical properties such as density and magnetic susceptibilities of mafic dykes and kimberlites, their geophysical signatures, emplacement of kimberlites at the close vicinity of mafic dykes or at their intersections have also been discussed. 相似文献
9.
双尖子山银铅锌矿位于大兴安岭中南段,是近年来该区域新发现的规模最大的银多金属矿,属热液型矿床并经历了多次矿化叠加。磁异常与金属矿有较强的相关性,磁性结构能够较好地反映控矿构造。本研究在各类先验信息约束下,对双尖子山铅锌矿区约1200 km2的高精度磁法数据进行了定性分析,并通过三维物性反演计算,得到了该区域地下5 km内的三维磁性结构,初步揭示了深部构造特征。获得的认识如下：(1)研究区高磁性岩体主要分布在中部和西北部,呈北东—南西向条带状展布。(2)基于磁性结构,将研究区划分为4个主要构造单元和6个次级构造单元;(3)研究区总体断裂构造呈北东—南西走向,南部断裂构造转为北西—南东走向;(4)研究区中部和东南部有较大范围的隐伏岩浆岩,且以中酸性岩浆岩为主。 相似文献
10.
A Comprehensive Investigation of an Offshore Active Fault in the Western Sagami Bay, Central Japan 总被引：1，自引：0，他引：1
Offshore active faults, especially those in the deep sea, are very difficult to study because of the water and sedimentary cover. To characterize the nature and geometry of offshore active faults, a combination of methods must be employed. Generally, seismic profiling is used to map these faults, but often only fault-related folds rather than fracture planes are imaged. Multi-beam swath bathymetry provides information on the structure and growth history of a fault because movements of an active fault are reflected in the bottom morphology. Submersible and deep-tow surveys allow direct observations of deformations on the seafloor (including fracture zones and microstructures). In the deep sea, linearly aligned cold seep communities provide indirect evidence for active faults and the spatial migration of their activities.The Western Sagami Bay fault (WSBF) in the western Sagami Bay off central Japan is an active fault that has been studied in detail using the above methods. The bottom morphology, fracture 相似文献
11.
《Geodinamica Acta》2013,26(6):401-405
Late Cretaceous to Palaeogene graben inversion in the southern North Sea is classically related to Alpine compression. Regional deformation analysis of Upper Cretaceous sediments based on seismic and well data reveals the existence of large-scale NW-SE folds. Folding patterns are interpreted as the result of lithospheric buckling during NE-SW shortening. We suggest that graben inversion at the scale of the southern North Sea is only a part of a more general process, involving lithospheric folding. Folding developed in response to two major plate boundary conditions, that is, E-W to NE-SW opening of the Atlantic Ocean constrained to the southeast by N-S Alpine collision. Lithospheric folding might have influenced both the oil generation process and reservoir properties in this area. 相似文献
12.
利用钻井、测井及地震资料,重建了南沙海域南部第三纪三角洲沉积的时空演化,并讨论了主控因素。研究表明,自晚渐新世—上新世,研究区三角洲在平行岸线方向(NE—SW)自西向东从西巴兰断层西侧向东侧迁移;在垂直岸线方向(NW—SE)则整体表现出从陆向海进积推进。这一演化过程主要受控于古南海自西向东"剪刀式"俯冲引起的造山带的迁移和海平面的升降。并且发现研究区烃源岩、储层和圈闭具有分期、分带特征。通过综合分析,在研究区划分出3个与三角洲有关的油气聚集区,即曾母盆地巴林坚三角洲油气聚集区、文莱—沙巴盆地巴兰三角洲油气聚集区、梅丽干—冠军三角洲油气聚集区。 相似文献
13.
The Portland Hills Fault: uncovering a hidden fault in Portland, Oregon using high-resolution geophysical methods 总被引：3，自引：0，他引：3
The Portland metropolitan area historically is the most seismically active region in Oregon. At least three potentially active faults are located in the immediate vicinity of downtown Portland, with the Portland Hills Fault (PHF) extending directly beneath downtown Portland. The faults are poorly understood, and the surface geologic record does not provide the information required to assess the seismic hazards associated with them. The limited geologic information stems from a surface topography that has not maintained a cumulative geologic record of faulting, in part, due to rapid erosion and deposition from late Pleistocene catastrophic flood events and a possible strike-slip component of the faults. We integrated multiple high-resolution geophysical techniques, including seismic reflection, ground penetrating radar (GPR), and magnetic methods, with regional geological and geophysical surveys to determine that the Portland Hills Fault is presently active with a zone of deformation that extends at least 400 m. The style of deformation is consistent with at least two major earthquakes in the last 12–15 ka, as confirmed by a sidehill excavation trench. High-resolution geophysical methods provide detailed images of the upper 100 m across the active fault zone. The geophysical images are critical to characterizing the structural style within the zone of deformation, and when integrated with a paleoseismic trench, can accurately record the seismic history of a region with little surface geologic exposure. 相似文献
14.
Francisco Gutiérrez Eulàlia Masana Álvaro González Pedro Lucha Jesús Guerrero James P. McCalpin 《International Journal of Earth Sciences》2009,98(7):1691-1703
The Munébrega Plio-Quaternary half-graben is a NW-SE trending neotectonic depression located in the central sector of the intraplate Iberian Range (NE Spain). The master fault of the half-graben offsets an Upper Pleistocene pediment deposit, forming an upslope-facing scarp. A trench dug across the fault scarp exposed a 25-m wide deformation zone consisting of graben and horst fault blocks with fissures in the upper part of the scarp, and a monoclinal flexure affected by normal and reverse faults in the lower part of the scarp. We infer a minimum of three faulting events over the past 72 ka, yielding an average (maximum) recurrence interval of 24 ka. The oldest event (72–41 ka) produced an antislope scarp on the relict pediment surface, confining deposition to the downthrown block. Cross-cutting faults affecting sedimentary units deposited in the sediment trap produced by the first event provide evidence for at least two younger events (33–19? ka). The measured cumulative vertical displacement (7.4 m) yield a minimum vertical slip rate of 0.10 ± 0.01 mm/year (2σ error) for the past 72 ka. If the paleoearthquakes ruptured the whole mappable length of the fault (ca. 20 km), they probably had moment magnitudes ca. 6.9 (Stirling et al. Bull Seismol Soc Am, 2002). Such earthquakes would have been more than a magnitude unit larger than the largest ones recorded historically in the Iberian Range. These results suggest that the official seismic hazard assessments, based solely on the historic and instrumental record, may underestimate the seismic hazard in the area. 相似文献
15.
海原-六盘山断裂是青藏高原东北缘的大型边界断裂带,是中国大陆典型的地震危险区。地壳构造加载特征的定量研究有助于分析区域孕震环境,参考青藏高原东北缘GPS形变和岩石圈精细结构等资料,本文建立海原-六盘山断裂带周缘的三维岩石圈分层模型,分析现今构造加载作用下区域地壳形变和应力演化特征。数值计算结果显示:青藏高原东北缘现今处于以北东-南西向的水平挤压为主导和北西-南东向的水平引张的变形特征。青藏高原东北缘中-下地壳流变性质影响上覆脆性地壳应力环境,中地壳较低粘滞系数对应的模型地壳应力计算值与研究区实际地壳应力场相近。海原断裂中-西段构造加载作用显著,具有相对较高的库仑应力积累和最大剪应力分布;而六盘山断裂周缘地壳应力和最大剪应力小于海原断裂带。构造应力积累的空间分布差异说明六盘山断裂具有较弱的构造孕震环境,而研究区走滑型断裂的孕震加载作用显著。尽管六盘山处于较低的应力状态,但仍不能轻易忽视其长期存在的强震空区所暗示的发震潜力。 相似文献
16.
Lineament analysis of Cannanore district and their implication on the tectonic evolution of the area
The Cannanore district and the adjoining areas mainly comprise of charnokites, gniesses, high and low-grade schists and various types of igneous intrusives. The lineament fabric of the region indicates that the NNW-SSE, NW-SE, ENE-WSW and NE-SW lineament directions are prominent. It is suggested that the area has undergone at least three distinct phases of tectonic activity. The NW-SE and ENE-WSW lineaments appear to have formed during the phase of NW-SE folding. The NE-SW lineaments may be the result of the cross-folding of the earlier folds. The NNW-SSE lineaments have been related to the Precambrian tectonic activity in South India. 相似文献
17.
Hamed Abdelhamid Alrefaee AbdEl-Aziz Khairy Abd el-aal 《Arabian Journal of Geosciences》2017,10(24):547
We utilized the seismicity and the potential field data to study the tectonic deformation and to delineate the seismically active subsurface tectonic trends of El-Faiyum area. To accomplish these goals, we analyzed and interpreted the seismicity data, the reduced to pole total magnetic intensity, and the Bouguer anomaly maps. We also used the spatial distribution of the recent seismic events and the focal mechanism to outline the local seismic zones that control the seismicity of the study area and to determine the sense of the motion along the subsurface active faults. The focal mechanism of the recent seismic events and the interpreted subsurface tectonic faults from the potential field data reflect strike-slip movements with normal components along the subsurface active faults. The gravity and magnetic maps show a NE-SW regional trend with low gravity and magnetic values. The NE-SW regional trend extends across the whole area and could be related to the Pelusium Megashear fault. A NE-SW trend with high gravity and magnetic exists at the northern part and coincides with the Kattania Uplift and the basaltic flows in Gabal Qatrani area. The gravity and magnetic maps also reveal several local anomalies with different polarities, amplitudes, and extensions, which reflect anticlinal and synclinal structures on the basement surface. The seismotectonic map, generated by linking the basement structure map and the spatial distribution of the recent earthquake foci, reveals the dominant tectonic trends and the subsurface active faults. 相似文献
18.
滇东北会泽地区位于扬子地台西缘,构造部位属欧亚板块,翻身村断裂带位于该地区中部,构造部位属寻甸-宣威断裂的北段,该断裂带北东方向延伸约57 km,宽0.5 km～2.6 km,2014年的鲁甸地震表明该断裂带仍然是一个构造活动带,为了达到防震减灾的目的,对翻身村断裂运动学的研究具有重要意义。应用小构造解析的方法对翻身村断裂运动序列进行了解析,得出6个变形序列,即①NW-SE构造挤压→②NW-SE构造挤压→③NNW-SSE构造拉伸→④近SN构造挤压→⑤NE-SW构造拉伸→⑥NWW-SEE构造挤压。翻身村断裂同时控制了区内的铅锌成矿带展布,铅锌矿体(脉)沿该断裂的北北东或北东向低级别、低序次层间裂隙充填,并于复合部位出现了相对较好的矿化。 相似文献
19.
Mohammed Benaafi Mustafa Hariri Osman Abdullatif Mohammed Makkawi Abdulaziz Al-Shaibani 《Arabian Journal of Geosciences》2017,10(5):106
The Wajid Group is a Cambro-Permian sedimentary succession in southwest Saudi Arabia. This group is a well-known groundwater aquifer in the Wadi Al-Dawasir and Najran areas. The group also represents siliciclastic hydrocarbon reservoirs in the Rub' Al-Khali Basin. The Wajid Group is exposed in an area extending from Wadi Al-Dawasir southward to Najran city. This study aims to map and characterize the lineament traces of the Wajid Group outcrops. Landsat-8 OLI/TIRS satellite images with 30-m resolution, Spot-5 satellite images with 2.5-m resolution and SRTM digital elevation models (DEM) with 30-m resolution were used for lineament trace detection. Those lineament traces supplemented by aeromagnetic lineaments detected from reduced to pole magnetic anomaly map of the studied outcrop. Multi-scale lineament trace maps were generated, and the lineament datasets, including orientation and length, were analyzed statistically. Eight lineament trace trends were identified including NW-SE, NNW-SSE, N-S, NNE-SSW, NE-SW, ENE-WSW, E-W, and WNW-ESE. The northerly, northwesterly, and northeasterly trending lineament traces are predominant. The lineament trace lengths are generally followed the power law distribution. The lineament trace trends were validated through field investigation of the Wajid Group outcrop. The reported outcrop fracture trends are consistent with major lineament trace trends. Lineaments within the Wajid Group outcrop are also consistent with those of the southern portion of the Arabian Shield. The results of this study provide insight into the tectonic origin of the Wajid Group outcrop lineaments, and understanding of the lineaments distribution which can help to predict the fluid flow behavior within the groundwater fractured aquifers or hydrocarbon fractured reservoirs in Rub’ Al-Khali Basin. 相似文献
20.
M. Meghraoui 《地学学报》1991,3(1):84-92
A shallow and damaging earthquake struck the region of Tipaza located on the coast, 70 km to the west of Algiers (north-central Algeria). The main shock was felt as far as 200 km from the epicentral area and particularly in the urbanized zone of Algiers. The main shock epicentre determined by CRAAG is on Mt Chenoua, close to the coastline. Coseismic surface breaks with 4.0 km of fault length and 7.0 cm of vertical displacement appeared on the southern side of Mt Chenoua. They consist of cracks and fissures on vertical bedding planes that belong to a Neogene flexure. The aftershock activity was recorded for several weeks and comprised more than 100 seismic events per day, with 1 < M < 5. Aftershocks are distributed in a ENE-WSW to NE-SW zone extending offshore. A NW-SE cross-section indicates that seismic events affect the crust to a maximum depth of 20 km, showing a complex fault-plane geometry dipping to the NW. For the main shock, the focal mechanism solution obtained from the readings of first motion polarities of seismograms yields an ENE-WSW reverse fault dipping to the NNW, which is in good agreement with both field observations and the aftershock distribution at depth.
The occurrence of the Mt Chenoua-Tipaza moderate-sized event in a previously identified active zone improves the seismotectonic characterization of this part of the Tellan Atlas mountains. This thrust and fold geological domain also shows active folds capable of producing larger earthquakes. Since only a small portion of the Sahel anticline ridge has been reactivated, a serious seismic hazard must be urgently recognized in the Algiers region. 相似文献
The occurrence of the Mt Chenoua-Tipaza moderate-sized event in a previously identified active zone improves the seismotectonic characterization of this part of the Tellan Atlas mountains. This thrust and fold geological domain also shows active folds capable of producing larger earthquakes. Since only a small portion of the Sahel anticline ridge has been reactivated, a serious seismic hazard must be urgently recognized in the Algiers region. 相似文献