共查询到20条相似文献，搜索用时 921 毫秒
1.
利用NGDC720地磁模型提供的磁异常数据, 分析了菲律宾海板块磁异常特征, 进而对磁异常进行多尺度分解, 给出了研究区岩石圈深部和浅部磁异常.结合热流分布特点和磁异常信息, 进一步分析了研究区引起磁异常成因.菲律宾海板块区域的磁异常既反映了该区域岩石圈浅部的构造特征, 也隐含深部构造信息.在西菲律宾海盆以及大东脊构造区, 浅部构造磁异常信息较好地继承了深部构造特征, 反映这些区域岩石圈的整体性特征.四国海盆与帕里西维拉海盆浅部磁异常信息显示了与近代(约10Ma)扩张轴一致的特征, 且磁异常与海底构造走向不一致; 而深部异常显示的帕里西维拉海盆磁异常走向与西菲律宾海盆一致的信息, 可能指示帕里西维拉海盆岩石圈曾与西菲律宾海盆有过类似的演化史. 相似文献
2.
成矿带的展布受地质构造的控制,而地质构造在重磁异常上有明显反映。为了研究秦岭造山带中段重磁异常与成矿
带的关系,该文系统整理、处理了秦岭造山带中段已获得的重磁力测量资料,分析研究了重磁异常的展布特征、推断了研
究区的断裂构造,讨论了结晶基底的起伏特征,并结合区域地质资料及矿床分布资料讨论了重磁场特征及其与地质构造、
成矿带的关系。结果表明,秦岭造山带中段成矿带均分布在重、磁异常梯度带上或几组不同方向异常的交汇部位,尤其在
局部重力高异常范围内及其边部梯度带上矿体富集。这一结果为研究秦岭造山带的地质演化、地质构造（尤其是深部构
造）、断裂分布及下一步的成矿有利区预测提供重要的参考信息。 相似文献
3.
Abdelhalim Miftah Driss El Azzab Ahmed Attou Ahmed Manar 《Arabian Journal of Geosciences》2017,10(21):460
Our investigation relates to the interpretation of the magnetic data of Jbel Saghro, by aeromagnetic processing using Geosoft and ArcGis software. The data were obtained from digitizing the preexisting maps. From the magnetic field anomaly maps, different anomalies were identified with differences in intensities, sizes, and shapes and in being isolated or interfered. The directions are in general ENE-WSW, NNW-SSE, W-E, and NW-SE which are in good agreement with the general tectonic structure of the region. In order to correspond the anomalies to their natural sources and their geometrical configuration, it was necessary to calculate the residual polar. This avoids the presence of two lobes for the same source, what makes it possible to delimit the geological sources laterally. Thus, the attribution of each magnetic anomaly to its geological source becomes possible. Indeed, generally magnetic anomaly of strong intensities and big wavelengths is associated to very magnetized structures related to the Precambrian basement, and the negative a.m. is connected to structures of weak magnetization located in general in the cover. The application of the tilt angle filter allowed the localization of the outcrops of the inliers and new geophysical lineaments. On the other hand, the local maxima of the horizontal gradient made it possible to reveal the large structural features concerning the main tectonic events of the area. 相似文献
4.
Zhao Pengda 《中国地质大学学报(英文版)》1995,(1)
Ｇｅｏｌｏｇｉｃａｌ Ａｎｏｍａｌｙ ｏｆ Ｃｈｉｎａ￥ＺｈａｏＰｅｎｇｄａ（ＦａｃｕｌｔｙｏｆＥａｒｔｈＲｅｓｏｕｒｃｅｓ，ＣｈｉｎａＵｎｉｖｅｒｓｉｔｙｏｆＧｅｏｓｃｉｅｎｃｅｓ，Ｗｕｈａｎ４３００７４）ＷａｎｇＪｉｎｇｇｕｉ；ＲａｏＭｉｎｇｈｕ... 相似文献
5.
From the data of the geomagnetic survey of the Indian equatorial region conducted during 1971, it has been possible to deduce the subsurface magnetic anomalies at each survey station. The vertical magnetic anomaly profiles seem to reflect some of the known geological structures in the region. The association between magnetic anomalies and the deep-seated structures in this area emphasises the importance of future intensive studies. 相似文献
6.
物化遥信息的精细化研究是归来庄金矿区找矿新突破的关键。该区化探区域异常范围大,数值高,和燕山期次火山成岩作用相一致,而成矿却和低缓局部异常相一致。重磁异常轴线错动、弯转较多,错动后的产状缓倾侧有利于成矿物质的富集。多期岩浆活动造成遥感多重环状构造交汇及线状与环状构造交汇。由此建立两条找矿主线:隐伏岩体边部、外缘-大中型的构造破碎带-产状变换部位-低缓地球化学区域异常-重磁异常产状倾缓-侧-遥感多重环状构造的交汇部位;地质构造环境的突变处-地球化学障-重磁等值线方向的突变-遥感线性构造的转折处。以归来庄金矿成矿模式为基础,对以上信息进行整合,建立了归来庄地区的找矿模型,并在此基础上优选了银洞沟、十字庄等三个找矿靶区。 相似文献
7.
东昆仑—阿尔金地区遥感地质解译与成矿预测 总被引：1，自引：0，他引：1
通过提取遥感找矿地质异常信息,从宏观和多角度预测矿床存在的有利区域。以东昆仑—阿尔金地区为例,通过运用影像纠正、假彩色合成与彩色空间变换、图像增强处理(比值、主成分分析等)、掩膜处理、数据融合以及遥感异常信息多层次筛选技术、影像镶嵌、地质信息综合分析等方法,提取与成(控)矿作用相关的蚀变异常信息和构造信息,确定了基于蚀变异常与线环构造信息的典型矿物遥感找矿模型,并结合多源信息对东昆仑—阿尔金地区进行了成矿预测。 相似文献
8.
琼北地区发育大量新生代火山岩,是了解东南亚新生代构造演化的重要窗口之一。本文利用琼北地区最新航磁资料,采用航磁ΔT原始数据进行化极、垂向一阶导数等频率域转换处理等方法,并结合琼北新生代火山岩研究的其它资料,对琼北新生代火山岩区域航磁特征以及典型地区航磁异常特征进行了分析。研究结果表明:琼北东部与西部区域磁场特征存在一定的差异,即其东部具有平缓变化的负磁场特征,而中—西部具有强烈升高正磁场特征,这可能与琼北平缓变化的负背景场上叠加的新生代火山岩磁性强弱以及在空间上分布的不均匀有关。琼北新生代火山构造航磁异常具有两种不同的类型,第一类其内环航磁异常表现为不规则椭圆状负磁异常,负异常周围被环形升高的串珠状正磁异常所包围,该类航磁异常可能由塌陷式盾状火山锥群引起;第二类其外环由多个圈闭不规则的串珠状正磁异常组成,环形构造内部总体为负异常,但中心分布两个强度较大的正异常,该类航磁异常可能与早期塌陷式盾状火山锥群并叠加晚期磁性玄武质岩浆活动有关。 相似文献
9.
K M SREEJITH M RADHAKRISHNA K S KRISHNA T J MAJUMDAR 《Journal of Earth System Science》2011,120(4):605-615
The 85°E Ridge extends from the Mahanadi Basin, off northeastern margin of India to the Afanasy Nikitin Seamount in the Central
Indian Basin. The ridge is associated with two contrasting gravity anomalies: negative anomaly over the north part (up to
5°N latitude), where the ridge structure is buried under thick Bengal Fan sediments and positive anomaly over the south part,
where the structure is intermittently exposed above the seafloor. Ship-borne gravity and seismic reflection data are modelled
using process oriented method and this suggest that the 85°E Ridge was emplaced on approximately 10–15 km thick elastic plate
(Te) and in an off-ridge tectonic setting. We simulated gravity anomalies for different crust-sediment structural configurations
of the ridge that were existing at three geological ages, such as Late Cretaceous, Early Miocene and Present. The study shows
that the gravity anomaly of the ridge in the north has changed through time from its inception to present. During the Late
Cretaceous the ridge was associated with a significant positive anomaly with a compensation generated by a broad flexure of
the Moho boundary. By Early Miocene the ridge was approximately covered by the post-collision sediments and led to alteration
of the initial gravity anomaly to a small positive anomaly. At present, the ridge is buried by approximately 3 km thick Bengal
Fan sediments on its crestal region and about 8 km thick pre- and post-collision sediments on the flanks. This geological
setting had changed physical properties of the sediments and led to alter the minor positive gravity anomaly of Early Miocene
to the distinct negative gravity anomaly. 相似文献
10.
Digital elevation model (DEM) images provide synoptic views of the Earth’s surface allowing the analysis of landforms of still
active tectonic and volcanic structures at regional scale. A DEM at 250 m pixel size constitutes regional scale data particularly
efficient to investigate the late Miocene–Quaternary deformation of the Eastern Turkish–Armenian Plateau in the Arabian–Eurasian
area of convergence. Geomorphic analysis of the DEM image associated with review of fault-plane solutions of earthquakes show
that faults are mostly strike-slip with small vertical component. Here we show that the orientations of the tectonic and volcanic
structures fit with a tectonic regime characterized by N–S shortening and E–W lengthening, consistent with westward escape
of Anatolia perpendicular to the direction of the Arabia–Eurasia shortening. The uniform uplift of the plateau, the predominance
of strike-slip faulting, the lack of major thrusts and the occurrence of normal faults do not support a model of going-on
crustal thickening due to intracontinental convergence. On the contrary, our observations can be better interpreted in terms
of lithospheric thinning and mantle upwelling related to gravity escape of Anatolia. 相似文献
11.
In order to probe the characters of tectonic structures in the study area, the authors conducted the 1:50 000 regional geochemical profile scan and took Huiyuan Temple area in Daofu County of Sichuan Province as a case study. The anomaly distribution and background value characters of the typical elements were compared with the known inferred faults, hidden rocks and geological boundaries. The results show that element (or anomaly) distribution characters correspond to the characters of fault activities, rocks and strata, which have been largely affected by the known geological structure (Xianshuihe Fault Zone). The formation and change of geochemical anomaly is closely related to those tectonic structures during the metallogenic period. Therefore, these data could be used to invert and infer the tectonic activity charaters. Based on the known faults and combined with the geochemical data and geological observation, the authors preliminarily inferred the spatial distribution of geological bodies and the locations of tectonic boundaries, and identified six inferred faults. This research aims to infer about those unknown regions and concealed geological structures, which provides some reference for future geological prospecting. 相似文献
12.
为查明研究区地质构造活动特征,以四川道孚县惠远寺地区为研究对象,开展了1:5万区域地球化学扫面工作,将典型元素的异常分布和背景值特征与区内已知断裂构造、出露岩体、地质界线等进行对比研究。结果表明: 元素(或异常)分布特征与断裂活动、岩体和地层分布相匹配,表现出受已知地质构造(鲜水河断裂带)的影响很大; 地球化学异常的形成和迁移与成矿期的构造作用密切相关,相关资料可用于反演推断地质构造活动特征; 在已知断裂的基础上,结合化探资料和地质观察,对地质体空间分布和构造界限的位置做出推测,初步厘定区内存在推测断层6条。该研究对未知地区和隐伏性地质构造提出推断,为后续找矿勘探提供依据。 相似文献
13.
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
14.
15.
《Journal of African Earth Sciences》2000,30(1):63-78
Gravity data were integrated with seismic refraction/reflection data, well data and geological investigations to determine a general crustal structure of Tunisia. The gravity data analysis included the construction of a complete Bouguer gravity anomaly map, residual gravity anomaly maps, horizontal gravity gradient maps and a 2.5-D gravity model. Residual gravity anomaly maps illustrate crustal anomalies associated with various structural domains within Tunisia including the Sahel Block, Saharian Flexure, Erg Oriental Basin, Algerian Anticlinorium, Gafsa Trough, Tunisian Trough, Kasserine Platform and the Tell Mountains. Gravity anomalies associated with these features are interpreted to be caused either by thickening or thinning of Palæozoic and younger sediments or by crustal thinning. Analysis of the residual gravity anomaly and horizontal gravity gradient maps also determined a number of anomalies that may be associated with previously unknown structures. A north-south trending gravity model in general indicated similar subsurface bodies as a coincident seismic model. However, thinner Mesozoic sediments within the Tunisian Trough, thinner Palæozoic sediments in the Gafsa Trough, and a greater offset on the Saharian Flexure were required by the gravity data. Additionally, basement uplifts under the Kasserine Platform and Gafsa Trough, not imaged by seismic data, were required by the gravity data. The gravity model revealed two previously unknown basins north and south of the Algerian Anticlinorium (5 km), while the Erg Oriental Basin is composed of at least two sub-basins, each with a depth of 5 km. 相似文献
16.
A. Castro C. Fernández H. El-Hmidi M. El-Biad M. Díaz J. de la Rosa F. Stuart 《International Journal of Earth Sciences》1999,88(1):26-37
The Aracena metamorphic belt (AMB), southwest Iberian peninsula, is characterized by the following geological elements: (a)
a high-temperature/low-pressure (HT/LP) metamorphic belt a few kilometres wide and more than 200 km long; (b) a linear belt
of oceanic amphibolites with a low-pressure inverted metamorphic gradient; (c) crustal-scale ductile shear zones; and (d)
mafic, noritic intrusions of high-Mg andesite (boninite) composition. The relationships between these elements led to the
proposal of a model of ridge subduction for this sector of the Hercynian belt of Europe. This interpretation is supported
by the age relationships displayed between the main rock units considered representative of the main tectonic and petrological
processes responsible for the geological elements mentioned previously. The results of a geochronological study (Ar–Ar, Rb–Sr
and Sm–Nd) clearly support a Late Paleozoic tectonic evolution at an active continental margin. The time evolution of the
metamorphism in the oceanic domain, ranging from 342.6±0.6 Ma in the west to 328.4±1.2 Ma in the east, over a distance of
70 km along the metamorphic belt, support a tectonic model of triple-junction migration responsible for the creation at depth
of a slab-free window with decisive consequences for the thermal evolution of the region. The origin of the linear metamorphic
belt of HT/LP regime may be explained by the migration along a continental margin of a punctual thermal anomaly induced by
the creation of a triple-junction at the continental margin.
Received: 9 March 1998 / Accepted: 9 December 1998 相似文献
17.
18.
Andrea Brogi 《International Journal of Earth Sciences》2008,97(4):677-703
The tectonic evolution of the Mt Amiata volcano-geothermal area is under discussion. Some authors state that this region,
as well as the hinterland of the Northern Apennines, were affected by compression from the Cretaceous to the Quaternary. In
contrast, most authors believe that extension drove the tectonic evolution of the Northern Apennines from the Early Miocene
to the Quaternary. Field data, seismic analyses and borehole logs have been integrated in order to better define the structural
features of the continental crust in the Mt Amiata geothermal area. In this paper I propose the hypothesis that the structure
of the crust in the Mt Amiata volcano-geothermal area derives from two main geological processes: (1) contractional tectonics
related to the stacking of the Northern Apennines (Cretaceous–Early Miocene), (2) subsequent extensional collapse of the hinterland
of the mountain chain, and related opening of the Northern Tyrrhenian Sea (Early Miocene–Quaternary). Compressional and extensional
structures characterise the Mt Amiata region, although extensional structures dominate its geological framework. In particular
the extension produced: (a) Middle-Late Miocene boudinage of the previously stacked tectonic units; (b) Pliocene–Quaternary
normal faulting which favoured the emplacement of a magmatic body in the middle-upper crust; and (c) the eruption of the Mt
Amiata volcano, which gave rise to an acid and intermediate volcanic complex (0.3–0.19 Ma). The extension produced the space
necessary to accommodate the Middle-Late Miocene marine and continental sediments. Pliocene and Quaternary normal and transtensional
faults dissected the previous structures and influenced the Early Middle Pliocene marine sedimentation within the structural
depressions neighbouring the Mt Amiata volcano. The magmatic body was emplaced at depth (about 6–7 km) during the Pliocene
extension, and produced the eruption of the Mt Amiata volcano during the Late Pleistocene. This gave rise to local uplift,
presently reaching about 3,000 m, as well as a negative Bouguer anomaly (−16 mgal), both centred on the Mt Amiata area. The
crustal dome shows a good correspondence with the convex shape of the regional seismic marker known as the K-horizon, which
corresponds to the 450°C isotherm, and the areas with greatest heat flow. This is probably a consequence of the above-cited
magmatic body presently in the process of solidification. A Late Pleistocene eruption occurred along a crustal fissure striking
N50° (Mt Amiata Fault), which crosscuts the crustal dome. Hydrothermal circulation, proven by the occurrence of thermal springs
and gas vents (mainly CO2 and H2S), mainly occurs along the Mt Amiata Fault both in the northeastern ans southwestern sides of the volcano. 相似文献
19.
In this paper, we introduce a new method called Forced Neural Network (FNN) to find the parameters of the object in geophysical
section respect to gravity anomaly assuming the prismatic model. The aim of the geological modeling is to find the shape and
location of underground structure, which cause the anomalies, in 2D cross section. At the first stage, we use one neuron to
model the system and apply back propagation algorithm to find out the density difference. At the second level, quantization
is applied to the density differences and mean square error of the system is computed. This process goes on until the mean
square error of the system is small enough. First, we use FNN to two synthetic data, and then the Sivas–Gürün basin map in
Turkey is chosen as a real data application. Anomaly values of the cross section, which is taken from the gravity anomaly
map of Sivas–Gürün basin, are very close to those obtained from the proposed method. 相似文献
20.
岩石圈磁场研究--卫星地磁学的一个新分支 总被引：8，自引：0，他引：8
评介了卫星磁测的历史和现状 ,并向读者推荐了全球和中国的卫星磁异常图以便研究利用 ;对中国境内的卫星磁异常进行了初步的解释 ,主要结果如下 :华北、塔里木和扬子地台与正异常重合 ,而碰撞造山带、褶皱带、山脉则与负异常重合 ;塔里木、四川、松辽盆地之下 ,都有一个扁平的、致密的磁性底座 ;西藏高原地壳中的磁性层在地表以下 30 km以内 ,其磁化率约为0 .0 163SI,相当于 I型花岗岩类的磁性 ;在南中国海海域 ,有两个伸展很大的磁性层 ,位于莫霍面上下 ,黄海海域的岩石圈内也有类似的一个磁性层。 相似文献