Lithospheric flexure and deformation-induced gravity changes: effect of elastic compressibility and gravitation on a multilayered, thick-plate model     

Jiaxiang Zhang  Teng-fong Wong 《Geophysical Journal International》1988,92(1):73-88

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Gravity Field Continuation of Irregularly Spaced Data Using Least Squares Collocation     

B. Lahmeyer 《Geophysical Journal International》1988,95(1):123-134

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Satellite Gravity Anomalies and Their Correlation with the Major Tectonic Features in the South China Sea   总被引：4，自引：0，他引：4  

Nguyen Nhu Trung  Sang-Mook Lee  Bui Cong Que 《Gondwana Research》2004,7(2):407-424

The South China Sea (SCS) is a region of interaction among three major plates: the Pacific, Indo-Australian and Eurasian. The collision of the Indian subcontinent with the Eurasian plate in the northwest, back-arc spreading at the center, and subduction beneath the Philippine plate along Manila trench in the east and the collision along Palawan trough in the south have produced complex tectonic features within and along the SCS. This investigation examines the satellite-derived gravity anomalies of the SCS and compares them with major tectonic features of the area. A map of Bouguer gravity anomaly is derived in conjunction with available seafloor topography to investigate the crustal structure. The residual isostatic gravity anomaly is calculated assuming that the Cenozoic sedimentary load is isostatically compensated. The features in the gravity anomalies in general correlate remarkably well with the major geological features, including offsets in the seafloor spreading segments, major faults, basins, seamounts and other manifestations of magmatism and volcanism on the seafloor. They also correlate with the presumed location of continental-oceanic crust boundary. The region underlain by oceanic crust in the central part of the SCS is characterized by a large positive Bouguer gravity anomaly (220–330 mgal) as well as large free-air and residual isostatic anomalies. There are, however, important differences among spreading segments. For example, in terms of free-air gravity anomaly, the southwest section of mid-ocean has an approximately 50 km wide belt of gravity low superimposed on a broad high of 45 mgal running NW–SE, whereas there are no similar features in other spreading segments. There are indications that gravity anomalies may represent lateral variation in upper crustal density structure. For instance, free air and isostatic anomalies show large positive anomalies in the east of the Namconson basin, which coincide with areas of dense volcanic material known from seismic surveys. The Red River Fault system are clearly identified in the satellite gravity anomalies, including three major faults, Songchay Fault in the southwest, Songlo Fault in the Northeast and Central Fault in the center of the basin. They are elongated in NW–SE direction between 20±30'N and 17°N and reach to Vietnam Scarp Fault around 16°30'N. It is also defined that the crustal density in the south side of the Central Basin is denser than that in the north side of the Central Basin.  相似文献   

A three-dimensional model of the Pyrenean deep structure based on gravity modelling, seismic images and petrological constraints     

Pierre Vacher  Annie Souriau 《Geophysical Journal International》2001,145(2):460-470

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Subsurface sediment accumulation patterns and their relationships with tectonic lineaments in the semi-arid Luni river basin, Rajasthan, Western India     

V. N. Bajpai  T. K. Saha Roy  S. K. Tandon 《Journal of Arid Environments》2001,48(4):603

Sediment accumulation patterns in the Luni basin have been studied on the basis of tubewell lithologs and Bouguer gravity anomaly profiles. East–West geologic transects using these data reveal several sediment-filled graben depressions, for example, the Digrana-Bhawal graben in the northern part, the Mangta-Sindari, Sindari-Bhimgoda, and Bhimgoda-Juna Motisara grabens in the central part; and the Dungari-Ratanpura and Ratanpura-Khanpur grabens in the southern part. Maximum sediment accumulation of more than 300 m is located in the southwestern part of the Luni basin, more specifically in the Ratanpura-Khanpur graben. Minor depressions also occur towards west of Jodhpur and east of Bhadrajun.Sediment filling in these graben depressions commenced with thick clay deposits followed by multistoried fining up sand and gravel sequences. Sediment accumulation centres are coincident with major tectonic lineaments and thus indicate that important loci of sediment accumulation are, possibly, a response to synsedimentary tectonics.  相似文献   

Spectral study of the Bouguer anomaly map of a rift valley and adjacent areas in Central India     

D. C. Mishra  R. K. Tiwari 《Pure and Applied Geophysics》1981,119(5):1051-1062

The spectral study of the Bouguer anomally map of Central India suggests an uplifted crust-mantle interface under the Mahandi graben. This study has delineated three subsurface levels of anomalous masses at the respective depths of 23 km, 8 km, and 2 km apparently representing the Moho, an intermediate discontinuity in the sialic part of the crust and the basement, respectively. Model study of the Bouguer anomaly along a profile suggests a typical continental graben type subsurface structure with a low density depression in the sialic part of the crust between 8 and 18 km supported by an elevated upper mantle of intermediate density (3.4 g/cm³) varying in depth from 25 km to 55 km. The depths of the inferred interfaces in case of Bundelkhand granite are 32 km, 11 km, and 1.5 km, which might represent the Moho, the base of intruded granite massif, and some shallow compositional variation. Similar studies in case of Vindhyan basin have brought out three discontinuities at the respective depths of 16 km, 6–4.5 km, and 2.4 km. The first horizon at the depth of 16 km probably represents the interface between the granitic and the basaltic part of the crust. The 6–4.5 km is the depth of the basement, with the 2.4 km interface separating Bijawar rocks from Vindhyans wherever they are present. A generalized inversion of a profile across a positive belt of Bouguer anomaly representing the subsurface Bijawar rocks support the above result.  相似文献   

Three-dimensional P-wave velocity structure in the upper crust beneath Kuju Volcano, central Kyushu, Japan     

Yasuaki Sudo  Yoshihiro Matsumoto 《Bulletin of Volcanology》1998,60(3):147-159

 Kuju Volcano lies near Aso Caldera at the center of Kyushu Island, western Japan. After a few hundred years of dormancy, a phreatic explosion accompanied by a small ash eruption occurred on 11 October 1995. This study was undertaken to determine the subsurface seismic velocity structure associated with the active magmatic regime in the Kuju volcanic region. The three-dimensional, upper crustal, P-wave velocity structure beneath Kuju Volcano was determined using methods for the simultaneous inversion of P-wave arrival times from local earthquakes in and around the Kuju volcanic region for velocities and hypocentral parameters. Results reveal two shallower low-velocity anomalies located in the northern and southern parts of Kuju Volcano, consistent with the presence of significant negative Bouguer gravity anomalies. In addition, a high-velocity anomaly is located approximately 5 km northwest of Mt. Kuju, one of the domes in Kuju Volcano. Beneath this high-velocity anomaly, a low-velocity anomaly is present. This velocity structure suggests a magmatic regime that has a lid consisting of cooled solid material overlying a chamber of partially molten material. Received: 23 September 1997 / Accepted: 20 June 1998  相似文献   

华北重力网测点重力变化特征与中强震的对应     

李青 《华北地震科学》2003,21(1):46-51

华北重力复测网（火车运输）始建于1972－1973年，三环共45个点，1986年起改用高精度LCR－G重力仪观测（仍保持三环，点位减到15个），至今已积累了16－33期重复观测资料。根据资料，华北网各测点重力值变化可分为三类，即1、有异常变化点；2、持续相对稳定点、3重力值有变化，但非深部物质引起或重力值无变化点。如果观测到的异常持续3－5年，且与背景相符，即有可能与中强震有关，并已被实践证明，因此，重力大跨度复测是中长期地震预报的一种有效手段。  相似文献   

有限范围的重力层间改正算法   总被引：1，自引：1，他引：0  

马健  魏子卿  武丽丽  杨正辉 《测绘学报》2017,46(1):26-33

层间改正是重力归算的一项重要内容,传统的平面层层间改正、球面层层间改正与地形改正的范围不一致,因此均存在远区虚拟地形引入的近似误差,且计算点高度越高,此误差越大。本文提出使用有限范围的层间改正进行重力归算的方法,使其区域范围与地形改正的范围一致。然后给出了有限范围层间改正的简便计算方法,该算法与通过地形改正严密积分法演化来的算法具有较好的一致性。内插试验说明当计算点地形高于1000m时,内插应使用基于有限范围层间改正的重力归算方法。  相似文献   

台湾的现代构造地貌及其深部重力机制问题     

刘光夏 《台湾海峡》1993,12(4):402-406

经过三维重力正演计算，我们从台湾的布格重力异常中求得了深部重力异常，其深度相当于地壳下层。分析对比之后发现，深部重力异常等植线的形态，较好地反映了台湾的现代构造地貌特征。如东部等值线的同步弯曲，犹如错断水系，反映现代板块运动的方向；中部大面积零值和负值线圈闭，反映中央山脉的整体上升；在一些等值线聚合成梯度的地带，又往往是某些深断裂的反映。是否可以这样认为，深部重力异常是地壳深处介质密度沿某一方向的  相似文献