共查询到20条相似文献，搜索用时 46 毫秒
1.
Bingqiang Yuan Lijun Song Li Han Shaole An Chunguan Zhang 《Geophysical Prospecting》2018,66(8):1586-1601
The Tobago Basin, which is located offshore northern Venezuela with a southern margin close to Trinidad and Tobago, has an area of approximately 59,600 km2. The Tobago Basin has relatively favourable hydrocarbon prospects, and to date, exploration work has mainly concentrated on small areas of the southwestern portion of the basin. To conduct a comprehensive study of the structural framework of the basin and the characteristics of the basement in order to identify prospective zones for hydrocarbon exploration, shipborne‐measured and satellite‐measured gravity data, shipborne‐measured magnetic data, and aeromagnetic survey data were analysed. A regularisation filtering method was used to separate and obtain regional and residual gravity and magnetic anomalies. Directional gradients of gravity and magnetic anomalies and the total horizontal gradient and vertical second derivative of gravity anomalies were employed to extract information about fault structures. Regression analysis methods were used to determine the basement depth. The geological significance of the gravity and magnetic fields was examined, the structural framework of the basin was assessed, the basement depth was estimated, and favourable hydrocarbon exploration prospects within the basin were identified. The results show that the Tobago Basin contains complex structures consisting mainly of two groups of faults trending in northeasterly and northwesterly directions and that the major northeasterly trending faults control the main structural configuration and depositional system within the basin. The basement of the Tobago Basin has deep rises and falls. It can be divided into the following four secondary tectonic units: the western sub‐basin, the central uplift area, the southern sub‐basin, and the northeastern sub‐basin. The central uplift area and northeastern sub‐basin are most likely to have developed hydrocarbon accumulations and should be targeted for further exploration. 相似文献
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This study provides evidence for post-5 Ma shortening in the transition area between the Dinarides fold-and-thrust belt and the Pannonian Basin and reviews possible earthquake sources for the Banja Luka epicentral area (northern Bosnia and Herzegovina) where the strongest instrumentally recorded earthquake (ML 6.4) occurred on 27 October 1969. Geological, geomorphological and reflection seismic data provide evidence for a contractional reactivation of Late Palaeogene to Middle Miocene normal faults at slip rates below 0.1 mm/a. This reactivation postdates deposition of the youngest sediments in the Pannonian Basin of Pontian age (c. 5 Ma). Fault plane solutions for the main 1969 Banja Luka earthquake (ML 6.4) and its largest foreshock (ML 6.0) indicate reverse faulting along ESE–WNW-striking nodal planes and generally N–S trending pressure axes. The spatial distribution of epicentres and focal depths, analyses of the macroseismic field and fault-plane solutions for several smaller events suggest on-going shortening in the internal Dinarides. Seismic deformation of the upper crust is also associated with strike-slip faults, likely related to the NE–SW trending, sinistral Banja Luka fault. Possibly, this fault transfers contraction between adjacent segments of the Dinarides thrust system. The study area represents the seismically most active region of the Dinarides apart from the Adriatic Sea coast and the bend zone around Zagreb. We propose that on-going thrusting in the internal Dinarides thrust system takes up a portion of the current Adria–Europe convergence. 相似文献
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Attila Aydemir Abdullah Ates Funda Bilim Aydin Buyuksarac Ozcan Bektas 《Surveys in Geophysics》2014,35(2):431-448
The North Anatolian Fault (NAF) is not observed on the surface beyond 40 km southeast of Karliova town toward the western shoreline of Lake Van. Various amplitudes of gravity and aeromagnetic anomalies are observed around the lake and surrounding region. In the gravity anomaly map, contour intensity is observed from the north of Mus city center toward Lake Van. There is a possibility that the NAF extends from here to the lake. Because there is no gravity data within the lake, the extension of the NAF is unknown and uncertain in the lake and to the east. Meanwhile, it is observed from the aeromagnetic anomalies that there are several positive and negative amplitude anomalies aligned around a slightly curved line in the east–west direction. The same curvature becomes much clearer in the analytic signal transformation map. The volcanic mountains of Nemrut and Suphan, and magnetic anomalies to the east of the Lake Van are all lined up and extended with this slightly curved line, provoking thoughts that a fault zone that was not previously mapped may exist. The epicenter of the major earthquake event that occurred on October 23, 2011 is located on this fault zone. The fault plane solution of this earthquake indicates a thrust fault in the east–west direction, consistent with the results of this study. Volcanic mountains in this zone are accepted as still being active because of gas seepages from their calderas, and magnetic anomalies are caused by buried causative bodies, probably magmatic intrusions. Because of its magmatic nature, this zone could be a good prospect for geothermal energy exploration. In this study, the basement of the Van Basin was also modelled three-dimensionally (3D) in order to investigate its hydrocarbon potential, because the first oil production in Anatolia was recorded around the Kurzot village in this basin. According to the 3D modelling results, the basin is composed of three different depressions aligned in the N–S direction and many prospective structures were observed between and around these depressions where the depocenter depths may reach down to 10 km. 相似文献
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Investigation into regional thermal structure of the Thrace Region, NW Turkey, from aeromagnetic and borehole data 总被引：1，自引：0，他引：1
Z. Mümtaz Hisarli M. Nuri Dolmaz Mahmut Okyar Ali Etiz Naci Orbay 《Studia Geophysica et Geodaetica》2012,56(1):269-291
The aeromagnetic values over the study region are relatively uniform except for a few anomalies in the northeastern and southwestern
areas. Analyses of aeromagnetic data were performed in NW Turkey, in order to have a look into the subsurface regional thermal
structure of the region. For this purpose, power spectra, reduced to pole (RTP), and band-pass filtered anomalies were produced
using geophysical techniques. Band-pass filtered data were produced from the RTP aeromagnetic anomalies to isolate near surface
and undesired deep effects. Based on the aeromagnetic data interpretation, the thickness of the magnetized crust, named the
Curie Point Depth (CPD), in the study area lies between 9.7 and 20.3 km. The CPD estimates in the Thrace region of Turkey
indicate two shallow CPD (SCPD1 and SCPD2) zones (the Istranca Massif and the Saros Graben area). The deep CPD are located
within the Thrace Basin with sediment thickness of about 9 km. The corresponding heat flow map prepared from the averaged
thermal conductivities and thermal gradients from the CPD reveals the existence of one low heat flow zone (75 mW/m2) over the center of Thrace Basin, and two high heat flow zones over the Istranca Masif (100–125 mW/m2) in the northern side and Saros Graben (125–135 mW/m2) areas in the southern side of the Thrace Basin. 相似文献
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Aeromagnetic anomalies uncover the Precambrian basement in the Chhattisgarh basin area,Central India
This paper presents aeromagnetic images for the Chhattisgarh basin region, in Central India, to provide a new window on Precambrian
basement geology and structure. On the basis of aeromagnetic patterns, the Chhattisgarh basin is sub-divided into a northern
low (negative) anomaly zone and a southern high (positive) anomaly zone. The northern portion of the main Chhattisgarh basin
has been further divided into two subbasins, the Hirri sub-basin in the west, and Baradwar sub-basin in the east. A prominent
negative anomaly delineates a NW-SE trending greenstone belt separating these sub-basins. Positive magnetic anomalies delineate
the extent of the Dongargarh granite and equivalents, while the weak magnetic anomaly in the southeast of the Dongargarh granite
and equivalents reflect granulite gneisses of the Eastern Ghat Mobile Belt. By applying the reduced-to-the-equator filter
we enhanced the possible magnetic sources and structural lineaments within the Chhattisgarh basin.
A new sketch map of structural elements was then compiled from aeromagnetic interpretation over the Chhattisgarh basin area.
It includes possible faults, folds and an inferred lithological boundary. 相似文献
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The Azambuja fault: An active structure located in an intraplate basin with significant seismicity (Lower Tagus Valley, Portugal) 总被引：2，自引：0，他引：2
The Azambuja fault is a NNE trending structure located 50 km NE of Lisbon, in an area of important historical seismicity. It is sited in the Lower Tagus Basin, a compressive foredeep basin related to tectonic inversion of the Mesozoic Lusitanian Basin in the Miocene. The fault is evident in commercial seismic reflection data, where it shows steep thrust geometry downthrowing the Cenozoic sediments to the east. It has also a clear morphological signature, presenting a NNE-SSW trending, east facing, 15 km long scarp, reaching a maximum height of 80 m. The fault scarp is the geomorphic appearance of a flexure expressed as a zone of distributed deformation, where Miocene and Pliocene sediments are tilted eastwards and are cut by steeply dipping meso-scale faults presenting reverse and normal offsets, with a net downthrow to the east. This pattern at the surface is compatible with a steep fault in the basement that tilts and branches through the overlying Cenozoic sedimentary cover. In order to constrain the neotectonic activity of this structure, detailed geological studies were conducted. Morphotectonics was studied through aerial photo interpretation, analysis of topographic maps and digital mapping. Those studies indicate Quaternary slip on the fault in the ranges of 0.05–0.06 mm per year. Seismogenic behaviour was assumed for the Azambuja fault based on the evidence of Quaternary tectonic activity and its location in an area of significant historical seismicity. M
w 6.4–6.7 maximum earthquakes, with recurrence intervals of 10000–25000 years, were estimated based upon the displaced morphological references, cumulative offsets and fault length. 相似文献
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The Ximalin fault is the northwest section of the Ximalin-Shuiquan fault, which is part of the north-edge fault zone of the Yanghe Basin, located in the conjunction of the Zhangjiakou-Bohai fault zone and Shanxi fault-depression basin, and its structural geometry and deformation characteristics can facilitate the research on the interaction of the two tectonic belts. In this paper, data of geological surveys and geophysical exploration are used to study this fault exhaustively, concerning its geometry, structural features and activity as well as its relationship with adjacent faults and rule in the deformation transform of the north-edge fault zone of the Yanghe Basin. The results show that the Ximalin Fault is a strike-slip feature with thrust component. Its vertical slip rates are 0.17mm/a and 0.25~0.38mm/a, and the horizontal slip rate is 0.58~0.67mm/a and 0.50mm/a during the late Middle Pleistocene and Holocene, respectively. It is formed alternately by the NW-trending main faults and secondary NE-trending faults, of which the former is characterized by high-angle reverse with sinistral strike-slip, and the latter shows normal faulting. The two sets of structures have specific structural geometry relations, and the motion manners and deformation characteristics match each other. During the active process of the north-edge fault of the Yanghe Basin, the NW trending Ximalin fault played a role similar to a transform fault in deformation change and stress transfer, and its sinistral strike slip activity accommodated the NE trending normal faulting at the both ends. 相似文献
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The Potiguar Basin is a ∼6,000 m thick aborted NE-trending rift that was formed during the Cretaceous in the continental margin of northeastern Brazil. Its ∼E–W-trending offshore faults form part of the successful continental margin rift that evolved into the South Atlantic Ocean. The region represents one of the most significant pre-Pangea breakup piercing points between eastern South America and West Africa. We used gravity, aeromagnetic, and geological data to assess the role of reactivated Precambrian shear zones and major terrain boundaries in the development of the Potiguar Basin from the Cretaceous to the Cenozoic. We also looked for possible links between these structures in northeastern Brazil and their continuation in West Africa. Our results indicate that the major fault systems of the Potiguar Basin were superimposed on the Precambrian fabric. Both gravity and magnetic maps show lineaments related to the shear zones and major terrain boundaries in the Precambrian crystalline basement, which also characterize the architecture of the rift. For example, the Carnaubais fault, the master fault of the rift system, represents the reactivation of the Portalegre shear zone, the major tectonic boundary between Precambrian terrains in the crystalline basement. In addition, part of the Moho topography is controlled by these shear zones and developed during the period of main rift extension in the Neocomian. The shear zones bounding the Potiguar rift system continue in West Africa around and underneath the Benue Basin, where fault reactivation also took place. 相似文献
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关于郯庐断裂和东北南部主要断裂的关系 总被引：1，自引：0，他引：1
利用东北地区航磁资料的新近编图和数据处理结果,结合重力和地质资料,本文探讨了郯庐断裂带的北延和依兰-伊通等东北南部主要断裂的关系。在晚太古代至早元古代郯庐断裂形成时,它向北延伸过渤海就止于鞍山,为另一东西向断裂所截。郯庐断裂由于后期的活动才使它越过东西向断裂继续向北伸展,形成了依兰-伊通断裂。依兰-伊通断裂切割地壳的深度和对两侧基底的控制作用都不如郯庐断裂中段强烈 相似文献
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New techniques for the integration of gravity and aeromagnetic data through rock physical property relationships are tested for the rapid location of potential iron oxide–copper–gold (IOCG) exploration targets across the Great Bear magmatic zone (GBMZ). These techniques are based on the recognition of coincident or near-offset magnetic and gravity anomalies associated with IOCG deposits, resulting from their intense and combined iron-oxide and alkali alteration. In the GBMZ, the NICO (Au–Co–Bi–Cu) deposit is an atypical magnetite-group IOCG hosted within an intensely hydrothermally-altered metasedimentary sequence. Prospectivity maps for the NICO area are derived from the integration of high-resolution aeromagnetic and surface gravity data with physical property measurements of magnetic susceptibility and density. Method 1 combines the pseudo-gravity (derived from the aeromagnetic data) and Bouguer gravity data to determine the locations of superimposed high anomalies. Method 2 estimates the apparent susceptibility and density subsurface distribution based on vertical prism models of the magnetic and gravity data. The apparent susceptibility data are transformed to apparent density using physical property relationships. The two apparent density datasets are then combined to determine the location of coincident magnetic and gravity derived anomalies. The results of these methods are supported by, and compared with, similar prospectivity maps generated through weights of evidence techniques. At NICO, the prospectivity maps accurately locate the deposit and nearby occurrences. Despite the lower resolution of the regional gravity data, application of the techniques across the GBMZ is successful at locating mineralised IOCG systems including the magnetite-group systems at Grouard, Fab, DeVries and Cole Lake, the magnetite to hematite-group systems of the Port Radium-Echo Bay district, and has highlighted possible targets for future exploration. 相似文献
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Fiona M. Campbell A. Kaiser H. Horstmeyer A.G. Green F. Ghisetti A.R. Gorman M. Finnemore D.C. Nobes 《Journal of Applied Geophysics》2010,70(4):332-342
In an attempt to understand the structure of active faults as they emerge from bedrock into shallow semi-consolidated and unconsolidated sediments, we have recorded a comprehensive high-resolution seismic reflection/refraction data set across the Ostler Fault zone on the central South Island of New Zealand. This fault zone, which absorbs 1–2 mm/yr of compression associated with oblique convergence of the Pacific and Australian tectonic plates, consists of a series of surface-rupturing N–S trending, west-dipping reverse faults that offset a thick sequence of Quaternary glacial outwash and late Neogene fluvio-lacustrine sediments of the Mackenzie Basin. Our study focuses on a region of the basin where two non-overlapping fault segments are separated by a transfer zone. Deformation in this area is accommodated by offsets on multiple small faults and by folding in their hanging walls. The seismic data with source and receiver spacing of 6 and 3 m and nominal CMP fold of 60 was acquired along twelve 1.2 km long lines orthogonal to fault strike and an additional 1.6 km long tie-line parallel to fault strike. The combination of active deformation and shallow glacial outwash sediments results in particularly complicated seismic data, such that application of relatively standard processing schemes yields only poor quality images. We have designed a pre- and post-stack reflection/refraction processing scheme that focuses on minimising random and source-generated noise, determining appropriate static corrections and resolving contrasting reflection dips. Application of this processing scheme to the Ostler Fault data provides critical information on fault geometry and offset and on sedimentary structures from the surface to ～ 800 m depth. Our preliminary interpretation of one of the lines includes complex deformation structures with folding and multiple subsidiary fault splays on either side of a ～ 50° west-dipping primary fault plane. 相似文献
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High resolution tomography of the Tanlu fault zone near Hefei with passive seismic and magnetotelluric linear array data 
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下载免费PDF全文 Jian Xu Kangdong Wang Junlun Li Ning Gu Ning Ding Jiawei Qian Wen Yang Haijiang Zhang 《地震科学（英文版）》2021,34(1):24-35
As the largest fault trending NNE-SSW to NE-SW in the eastern Eurasia Continent,the Tanlu fault zone(TLFZ)extends over 2,400 km within China,roughly from Wuxue,Hubei Province,to Russia.Since the Quaternary period,the TLFZ has been an earthquake-prone area in eastern China where several major earthquakes resulted by tectonic compression occurred,causing tremendous casualties and significant economic losses.Many studies on different segments of the TLFZ have been carried out in the past few decades.However,numerous key questions regarding the fault zone remain unanswered due to a lack of clear subsurface characterization and fault delineation.In this study,we present high-resolution tomographic results across the TLFZ to the east of Hefei,where one 22-km-long passive seismic array with densely spaced short-period nodes,and a 24-km-long magnetotelluric array were deployed adjacent to each other.We find the velocity and resistivity variations are highly consistent with known surface geology.Sharp property contrasts in both the seismic shear wave velocity and electrical resistivity profiles clearly delineate the Tanlu F1 fault(TLF-1)near Hefei.More interestingly,an upwelling with distinct high velocity is imaged within the Hefei Basin to the west of the TLF-1,whereas a slanted block with low-velocity and low-resistivity seems to cut into or thrust upon the high-grade to low-grade middle-pressure rocks in the Zhangbaling uplift right below the Tanlu F2 ductile shear fault(TLF-2).The presented results show a new approach to characterize deep subsurface structure of the TLFZ beyond 2-km depths using passive data,which it is often difficult for active seismic surveys with refracted and reflected waves to image. 相似文献
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Cenozoic structural deformation and expression of the “Tan-Lu Fault Zone” in the West Sag of Liaohe Depression, Bohaiwan basin province, China 总被引：1，自引：0，他引：1
Based on the interpretation of 3D seismic data and structural mapping we analyzed the geometry and kinematics of the fault system and validated the expression of the “Tan-Lu Fracture Zone” in the West Sag of Liaohe Depression, Bohaiwan basin province. The Cenozoic structural deformation within the West Sag of Liaohe Depression can be divided into extensional structure system and dextral structure system. The extensional system is constituted by numerous NNE-NE trending Paleogene normal faults, where the Taian-Dawa fault (F1) is the master boundary fault (MBF) dominating the deposition during Paleogene so that the sag shows a complex half-graben with “boundary fault in the east and overlap in the west”. The dextral system is constituted by 2–3 dextral basement faults in NNE-NE trending (F2, F3, F4) and associated structure, and the time of structural action started in Oligocene and continued to Quarternary so that some associated secondary faults of the dextral system cut off the Neogene and Quaternary. Under the influence of the position and attitude of NNE-NE trending basement strike-slip faults, the central north part and the south part of the West Sag show obviously different structural features. The former appears to be a complex “graben” structure limited by the reversed strike-slip fault in the west and bounded by the inverted normal fault in the east, the latter remains the complex half-graben structure with “boundary fault in the east and overlap in the west”, and the graben was mildly reconstructed by one or two normal strike-slip faults. The dextral system within the West Sag is the element of the west branch fault of the Tan-Lu Fracture Zone, which is a deep fracture zone extending along the east of the Liaodongwan Gulf. The deep fracture zone branches off into two separate faults within the Liaohe Depression. The east branch goes through from northern part of the Liaodongwan Gulf to the East Sag of Liaohe Depression and links with the Denghua-Mishan Fault near Shenyang, and the west branch passes from northern part of the Liaodongwan Gulf to the West Sag and Damintun Sag of Liaohe Depression and links with the Yilan-Yitong Fault. The principal displacement zone of the west branch of the Tan-Lu Fracture Zone cuts off the master extensional fault (F1) within the West Sag of Liaohe Depression and induces many cover faults in EW trending within the Neogene and Quaternary. 相似文献
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Introduction As the capital of China, Beijing is a major political, economic and cultural center. In 2008, it will host the Olympic Games. Therefore, Beijing is of great importance in our national undertak-ing in guarding against earthquakes and reducing their damages. The Chinese Capital Circle re-gion has always been attached great importance in monitoring earthquakes by the China Earth-quake Administration, and as the kernel of the Capital Circle region, Beijing is the key area for ea… 相似文献