Artykuły w czasopismach na temat „Euler pole estimate”
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Goudarzi, Mohammad Ali, Marc Cocard i Rock Santerre. "EPC: Matlab software to estimate Euler pole parameters". GPS Solutions 18, nr 1 (22.11.2013): 153–62. http://dx.doi.org/10.1007/s10291-013-0354-4.
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Goudarzi, Mohammad Ali, Marc Cocard i Rock Santerre. "ESTIMATING EULER POLE PARAMETERS FOR EASTERN CANADA USING GPS VELOCITIES". Geodesy and Cartography 41, nr 4 (17.12.2015): 162–73. http://dx.doi.org/10.3846/20296991.2015.1123445.
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Eastern Canada is characterized by many intraplate earthquakes mostly concentrated along the Saint Lawrence River and Ottawa River valleys. After the rigid plate rotation of North America, the glacial isostatic adjustment (GIA) is by far the largest source of geophysical signal in eastern Canada. We estimate a set of Euler pole parameters for this area using a velocity field of 19 continuously operating GPS stations out of 112, and show that they are different from the overall rotation of the North American plate. This difference potentially reflects local stresses in this seismic region, and the difference in intraplate velocities between the two flanks of the Saint Lawrence River valley accumulate stress along the river.
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Schreider, Al A., A. A. Schreider, A. E. Sazhneva, M. S. Kluev i A. L. Brehovskih. "Kinematic model of the Midoceanic Gakkel ridge East areas development in the Eurasian basin of the Arctic ocean". Океанология 59, nr 1 (18.04.2019): 143–52. http://dx.doi.org/10.31857/s0030-1574591143-152.
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The new map of linear magnetic anomalies axis for the mid-Arctic ridge east areas development in the Eurasian basin is made. The domestic geomagnetic investigations for the first time allow to determine paleomagnetic anomaly C25 and estimate the time of transfer rifting to spreading process as chrons С25r-С26n (57.656-59.237 ma). The eastablishing of Lomonosov ridge and Siberian margin splitting zone is made. The Euler pole for the splitting kinematic for first time calculated. The nocoinciding of conjugate isobaths related to process of sliding peripheral continental crust areas along lithosphere thrust plane for the first time is calculate.
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Ibe Alexander Omenikolo, Terhemba Theophilus Emberga i Alexander Iheanyichukwu Opara. "Basement depth re-valuation of anomalous magnetic bodies in the lower and middle Benue trough using Euler deconvolution and spectral inversion techniques". World Journal of Advanced Research and Reviews 14, nr 2 (30.05.2022): 129–45. http://dx.doi.org/10.30574/wjarr.2022.14.2.0356.
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Spectral technique and Euler Deconvolution were applied to high-resolution aeromagnetic data of parts of Benue trough to estimate the depth of anomalous magnetic sources within the study area; Data enhancement techniques such as total magnetic intensity map, reduction to pole, regional-residual separation and upward continuation maps were employed to identify different magnetic anomalies, structural trends representing the tectonics of the location were observed trending NE-SW and N-S directions; The result of 3D Euler deconvolution for the structural index (SI) = 0, 1, 2, 3 gave depths to magnetic sources that range from -589;3 m to -2678;8 m, -459;0 m to -2691;9 m, -294;6 m to -2817;5 m, - 430;2 m to -2780;6 m respectively; The depth estimates from 2-D spectral revealed a two-layer model; The shallow magnetic depth ranges between 0;135 km to 0;200 km with a mean depth of 0;158 km and the depth to magnetic basement vary between 2;585 km to 4;878 km with a mean depth of 3;415 km; This result, therefore, indicates that the average basement depth of the study area obtained from the spectral analysis is 3;415km; This investigation, therefore provides appropriate sedimentary thickness for suitable hydrocarbon prospecting within the study area.
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Nurmufti Adam, Jiyon Ataa, Nurrohmat Widjajanti i Cecep Pratama. "Estimation of Slip Rate and the Opak Fault Geometry Based on GNSS Measurement". IOP Conference Series: Earth and Environmental Science 1039, nr 1 (1.09.2022): 012058. http://dx.doi.org/10.1088/1755-1315/1039/1/012058.
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Abstract GNSS observations are usually used in periodic deformation monitoring. The Opak fault, which was in the Special Region of Yogyakarta, became a concern after the 2006 earthquake. The horizontal velocity values of each observation station are needed to estimate the slip rate and locking depth values of the Opak fault. The magnitude of the velocity vector is computed by the linear least square method, then translated into the Sunda Block reference frame. The creep of fault assumption is used in analyzing the potential for the earthquake in the Opak fault region. The velocity is done by reducing the Sunda Block using the Euler pole method, and it produces a velocity vector value on the east component is -6.08 to 5.25 mm/year while the north component is -3.38 to 5.74 mm/year. Meanwhile, in the northern segment of the Opak fault, the estimated slip rate is around 3.5 to 10.5 mm/year, with the locking depth obtained of 1.1 to 8 km, while in the southern segment of the Opak fault, the estimated slip rate is 4 to 5.5 mm/year, with a locking depth obtained of 0.6 to 1.2 km. The creep of the fault effect is predominantly in the southern segment of the Opak fault. This case indicates that the potential for earthquake hazards is smaller in the south segment than in the north segment.
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Kolyanova, A. S., i Y. N. Yaltsev. "MISORIENTATION DISTRIBUTION FUNCTION FOR CUBIC CRYSTALS". Industrial laboratory. Diagnostics of materials 85, nr 5 (5.06.2019): 28–32. http://dx.doi.org/10.26896/1028-6861-2019-85-5-28-32.
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A calculation method for obtaining the misorientation distribution function (MDF) for cubic crystals which can be used to estimate the presence or absence of special boundaries in the materials is presented. The calculation was carried out for two samples of Al-Mg-Si alloy subjected to various mechanical and thermal treatments: the first sample is subjected to rolling; the second sample is subjected to recrystallization annealing. MDF is calculated for each sample; the results are presented in the Euler space and in the angle-axis space. The novelty of the method consists in the possibility of gaining data on the grain boundaries from X-ray texture analysis without using electron microscopy. A calculation involving only mathematical operations on matrices was performed on the basis of the orientation distribution function restored from incomplete pole figures. It is shown that no special boundaries are observed in the deformed sample, whereas in the recrystallized alloy, special boundaries are detected at Ʃ = 23, 13, and 17. The shortcoming of the proposed method can be attributed to the lack of accurate data on grain boundaries, since all possible orientation in the polycrystal should be taken into account in MDF calculation.
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A, Saleh, Udensi E.E., Salako K.A. i Unuevho, C.I. "DELINEATION OF AIRBORNE MAGNETIC AND RADIOMETRIC STRUCTURES ASSOCIATED WITH GOLD MINERALIZATION OF MINNA AND ITS ENVIRONS, NORTHCENTRAL NIGERIA". Earth Sciences Pakistan 6, nr 2 (2022): 54–59. http://dx.doi.org/10.26480/esp.02.2022.54.59.
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This study utilized the interpretation of the airborne magnetic and radiometric data to delineate the potential structures that are associated with gold mineralization of the Minna and its environs, Northcentral Nigeria. The total field anomaly data was reduced to pole and upward continued in a bid to well positioned and enhanced the shallow (high pass) magnetic structures. The high pass structural lineaments were extracted and the resulting prominent E-W and NE-SW tectonic trends were revealed which are perhaps related to Eburnean (D1) and Pan-African (D2) deformation events respectively. Subsequently, numerous regions with relatively high degree of faulting and shearing effects were unraveled from the line density analysis of the high pass lineaments. The 3-D Euler deconvolution technique provides a synonymous trend pattern with the HP lineaments as well as estimate the depth extents to the potential structures with values varying between 82.7 and 211.9 m. It was found that the mineralized structures associated with gold over the study area interact with the hydrothermal fluids alongside/adjacent to the structurally deformed (relatively high degree of faulting and shearing effects) regions. The observed regions with coincident, of the hydrothermally altered and structurally deformed are therefore marked as the resourceful, structures for gold mineralization. Hence, the derived evidence from this study has updated the information on the structures that are associated with gold mineralization and also acts a mitigation major against the indiscriminate excavations of the studied region.
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Fedi, Maurizio. "DEXP: A fast method to determine the depth and the structural index of potential fields sources". GEOPHYSICS 72, nr 1 (styczeń 2007): I1—I11. http://dx.doi.org/10.1190/1.2399452.
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We show that potential fields enjoy valuable properties when they are scaled by specific power laws of the altitude. We describe the theory for the gravity field, the magnetic field, and their derivatives of any order and propose a method, called here Depth from Extreme Points (DEXP), to interpret any potential field. The DEXP method allows estimates of source depths, density, and structural index from the extreme points of a 3D field scaled according to specific power laws of the altitude. Depths to sources are obtained from the position of the extreme points of the scaled field, and the excess mass (or dipole moment) is obtained from the scaled field values. Although the scaling laws are theoretically derived for sources such as poles, dipoles, lines of poles, and lines of dipoles, we give also criteria to estimate the correct scaling law directly from the data. The scaling exponent of such laws is shown to be related to the structural index involved in Euler Deconvolution theory. The method is fast and stable because it takes advantage of the regular behavior of potential field data versus the altitude [Formula: see text]. As a result of stability, the DEXP method may be applied to anomalies with rather low SNRs. Also stable are DEXP applications to vertical and horizontal derivatives of a Newtonian potential of various orders in which we use theoretically determined scaling functions for each order of a derivative. This helps to reduce mutual interference effects and to obtain meaningful representations of the distribution of sources versus depth, with no prefiltering. The DEXP method does not require that magnetic anomalies to be reduced to the pole, and meaningful results are obtained by processing its analytical signal. Application to different cases of either synthetic or real data shows its applicability to any type of potential field investigation, including geological, petroleum, mining, archeological, and environmental studies.
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Hang, Nguyen Thi Thu, Erdinc Oksum, Le Huy Minh i Do Duc Thanh. "An improved space domain algorithm for determining the 3-D structure of the magnetic basement". VIETNAM JOURNAL OF EARTH SCIENCES 41, nr 1 (8.01.2019): 69–80. http://dx.doi.org/10.15625/0866-7187/41/1/13550.
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The paper presents an improved algorithm based on Bhaskara Rao and Ramesh Babu’s algorithm to invert magnetic anomalies of three-dimensional basement structures. The magnetic basement is approximated by an ensemble of juxtaposed vertical prisms whose bottom surface coincides with Curie surface with the known depth. The computer program operating with the proposed algorithm is built in Matlab environment. Test applications show that the proposed method can perform computations with fast and stable convergence rate where the results also coincide well with the actual model structure. The effectiveness of the method is demonstrated by inverting magnetic anomalies of the southeast part of Vietnam continental shelf. The calculated magnetic basement relief of the study area provides useful additional information for studies in the aim of dealing with the geological structure of the area.References Beiki M., 2010. Analytic signals of gravity gradient tensor and their application to estimate source location, Geophysics, 75(6), i59–i74.Bui C.Q. (chief author), Le T., Tran T. D., Nguyen T. H., Phi T.T., 2007. Map of deep structure of the Earth’s crust, Atlas of the characteristics of natural conditions and environment in Vietnam’s waters and adjacent region. Publisher of Science and Technology, Ha Noi. Do D.T., Nguyen T.T.H., 2011. Atempt the improvement of inversion of magnetic anomalies of two dimensional polygonal cross sections to determine the depth of magnetic basement in some data profile of middle off shelf of Vietnam. Journal of Science and Technology, Vietnam Academy of Science and Technology, 49(2), 125–132.Do D.T., 2013. Study for application of 3D magnetic and gravity method to determine density contribution of basement rock and depth of magnetic basement on Vietnam’s shelf for oil research and prospecting Vietnam National University, Hanoi, Project code QG-11-04. Keating P. and Pilkington M., 2000, Euler deconvolution of the analytic signal, 62nd Annual International Meeting, EAGE, Session P0193.Keating P., Zerbo L., 1996. An improved technique for reduction to the pole at low latitudes, Geophysics, 61, 131–137.Le H.M., Luu V.H., 2003. Preliminary interpretation of the magnetic anomalies of the Eastern Vietnam sea and adiacent regions. J. Sci. of the Earth, 25(2), 173–181. Mai T.T., Pham V.T., Dang V.B., Le D.B., Nguyen B., Le V.D., 2011. Characteristics of Pliocene - Quaternary geology and Geoengineering in the Center and Southeast parts of Continental Shelf of Vietnam. J. Sci. of the Earth, 33(2), 109-118.Mushayandebvu M.F., Lesur V., Reid A.B., Fairhead J.D., 2004. Grid Euler deconvolution with constraints for 2D structures, Geophysics, 69, 489–496.Nguyen N.T., Bui V.N., Nguyen T.T.H., Than D.L., 2014a. Application of power density spectrum of magnetic anomaly to estimate the structure of magnetic layer of the earth crust in the Bac Bo gulf. Journal of Marine Science and Technology, 14(4A), 137–148.Nguyen N.T., Bui V.N., Nguyen T.T.H., 2014b. Determining the depth to the magnetic basementand fault systems in Tu Chinh - Vung May area by magnetic data interpretation. Journal of Marine Science and Technology, 14(4A), 16–25.Nguyen T.T.H., Pham T.L., Do D.T., Le H.M., 2018. Improving algorithm of determining the coordinates of the vertices of the polygon to invert magnetic anomalies of two-dimensional basement structures in space domain, Journal of Marine Science and Technology (preparing to print).Parker R.L., 1973. The rapid calculation of potential anomalies, Geophys. J. Roy. Astron. Soc, 31, 447–455. Pilkington M., Gregotski M.E., Todoeschuck J.P., 1994. Using fractal crustal magnetization models in magnetic interpretation, Geophysical Prospecting, 42, 677–692.Pilkington M., 2006. Joint inversion of gravity and magnetic data for two-layer models, Geophysics, 71, L35–L42.Rao D.B., Babu N.R., 1993. A fortran 77 computer program for three dimensional inversion of magnetic anomalies resulting from multiple prismatic bodies, Computer & Geosciences, 19(8), 781–801.Tanaka A., Okubo Y., Matsubayashi O., 1999. Curie point depth based on spectrum analysis of the magnetic anomaly data in East and Southeast Asia, Tectonic Pphysics, 306, 461–470.Thompson D.T., 1982. EULDTH – A new technique for marking computer-assisted depth estimates from magnetic data, Geophysics, 47, 31–37.Vo T.S., Le H.M., Luu V.H., 2005. Determining the horizontal position and depth of the density discontinuties in Red River Delta by using the vertical derivative and Euler deconvolution for the gravity anomaly data, Vietnam. Journal of Geology, Series A, 287(3–4), 39–52. Werner S., 1955. Interpretation of magnetic anomalies of sheet-like bodies, Sveriges Geologiska Undersokning, Series C, Arsbok, 43, 6.Xu S.Z., 2006. The integral-iteration method for continuation of potential fields, Chinese journal of geophysics (in Chinese), 49(4), 1176–1182.Zhang C., Huang D.N., Zhang K., Pu Y.T., Yu P., 2016. Magnetic interface forward and inversion method based on Padé approximation, Applied Geophysics, 13(4), 712–720.CCOP, 1996. Magnetic anomaly map of East Asia, scale 1:4.000.000, Geological survey of Japan and Committee for co-ordination of joint prospecting for mineral resources in asian offshore areas.
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Singh, Arjun, G. M. Bhat i Yudhbir Singh. "Assessment of Velocity pattern of Lithotectonic Segments of the Kashmir Himalaya: Constraints from GPS measurements". Journal of The Indian Association of Sedimentologists 39, nr 1 (30.06.2022): 96–101. http://dx.doi.org/10.51710/jias.v39i1.235.
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We present the estimated horizontal velocities of different lithotectonic segments of the NW Himalaya using data recorded by the eighteen GPS observatories installed in the Jammu and Kashmir region. The data was acquired from 2016 to 2019 and was processed using high precision GAMIT/GLOBK software. With respect to ITRF08 reference frame, the site motion in the region varies from 35 mm/yr to 45 mm/yr towards north-east. The India fixed site motion was estimated using the Ader's Euler pole of rotation. This yielded site motion varying from 2.4 to 11 mm/yr towards south-west and is consistent with the reported plate motion in the Northwest Himalaya. Further study with additional GPS networks is expected to provide precise estimates of deformation in the locked and creeping zones of the main Himalayan thrust in the Northwest Himalaya.
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Handyarso, Accep, i A. D. Mauluda. "PENERAPAN METODE DEKONVOLUSI EULER UNTUK ESTIMASI KEDALAMAN SUMBER ANOMALI". GEOMATIKA 24, nr 1 (6.07.2018): 21. http://dx.doi.org/10.24895/jig.2018.24-1.726.
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<p>Metode gayaberat merupakan salah satu metode geofisika yang kerap digunakan dalam studi pendahuluan cekungan sedimen. Metode ini memiliki resolusi lateral yang baik namun tidak pada resolusi vertikalnya. Metode Dekonvolusi Euler merupakan salah satu metode estimasi kedalaman sumber anomali pada data gayaberat. Keberadaan lapisan New Guinea Limestone Group di Cekungan Bintuni menyebabkan berbagai permasalahan dalam proses interpretasi. Estimasi ketebalan New Guinea Limestone Group ini dapat dilakukan berdasarkan data anomali residual gayaberat dan algoritma inversi tertentu. Metode Dekonvolusi Euler diterapkan pada data sintetik dan data lapangan di Cekungan Bintuni (daerah Mogoi, Papua Barat). Hasil penerapan metode Dekonvolusi Euler pada data sintetik memberikan solusi kedalaman yang sesuai dengan model bawah permukaan. Penerapan metode Dekonvolusi Euler pada data lapangan menghasilkan kedalaman anomali antiklin dengan kelurusan Tenggara – Barat Laut pada 2513.95 m dan kedalaman anomali antiklin dengan kelurusan Barat Daya – Timur Laut pada 2860.31 m. Diduga terjadi penambahan kedalaman ke arah timur daerah penelitian, hal ini sesuai dengan pola konfigurasi <em>basement</em> di daerah penelitian yang semakin dalam ke arah Timur. Solusi Dekonvolusi Euler tersebut digunakan sebagai informasi awal pada saat melakukan inversi data gayaberat berdasarkan algoritma inversi <em>planting density anomalies</em>. Berdasarkan hasil inversi tersebut diperoleh ketebalan sumber anomali yang diinterpretasikan sebagai <em>New Guinea Limestone</em><em> Group</em> sekitar ±2000.00 m.</p><p><strong>Kata kunci</strong>: gayaberat, estimasi kedalaman sumber, Dekonvolusi Euler, inversi gayaberat, mogoi</p>
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Kim, A. Yu, M. F. Amoyan i V. E. Khapilin. "Static calculation of the bearing capacity of a two-pole membrane-rod system taking into account the air-bearing effect using the numerical Euler-Cauchy procedure". Herald of Dagestan State Technical University. Technical Sciences 48, nr 4 (11.02.2022): 159–70. http://dx.doi.org/10.21822/2073-6185-2021-48-4-159-170.
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Objective. The purpose of this study is to create a light, sufficiently rigid bearing coating, which can be strengthened by the air-supporting effect during overloads during force majeure. These structures can be erected in a very short time, both in combat conditions and during natural disasters. Method. The study was carried out in the software package "Program for calculating membrane-pneumatic structures by the step method using the numerical Euler-Cauchy procedure" according to the method of static calculation of membrane-pneumatic systems, taking into account non-linear factors. Result. A method for calculating air-supported double-belt membrane-rod systems for covering large spans by the iterative method of parameter increments using FEM and the Euler-Cauchy numerical procedure of the third order of accuracy has been developed. Conclusion. In design practice, the effect of strengthening the coating due to the air-supporting effect can approximately be taken equal to three. The use of the air-supported effect makes it possible to save significant funds, sometimes reaching up to 25% of the estimated cost of the structure due to the use of structural elements of a smaller section.
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Rodrigues, Rafael Saraiva, David Lopes de Castro i João Andrade dos Reis Júnior. "CHARACTERIZATION OF THE POTIGUAR RIFT STRUCTURE BASED ON EULER DECONVOLUTION". Revista Brasileira de Geofísica 32, nr 1 (1.03.2014): 109. http://dx.doi.org/10.22564/rbgf.v32i1.400.
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ABSTRACT. The Euler deconvolution is a semi-automatic interpretation method of potential field data that can provide accurate estimates of horizontal position and depth of causative sources. In this work we show the application of 3D Euler Deconvolution in gravity and magnetic maps to characterize the rift structures of the Potiguar Basin (Rio Grande do Norte and Ceará States, Brazil) using the structural index as a main parameter, which represents an indicator of the geometric form of the anomalous sources. The best results were obtained with a structural index equal to zero (for residual gravity anomalies) and 0.5 (for magnetic anomalies reduced to the pole), a spatial window size of 10 km, which is used to determine the area that should be used in the Euler Deconvolution calculation, and maximum tolerance of error ranging from 0 to 7%. This parameter determines which solutions are acceptable. The clouds of Euler solutions allowed us to characterize the main faulted limits of the Potiguar rift, as well as its depth, dip and structural relations with the Precambrian basement. Keywords: Euler deconvolution, potential field, structural index, Potiguar rift. RESUMO. A deconvolução de Euler é um método de interpretação semiautomático de dados de métodos potenciais, capaz de fornecer uma estimativa da posição horizontal e da profundidade de fontes anômalas. Neste trabalho, mostraremos a aplicação da deconvolução de Euler 3D em mapas gravimétricos e magnéticos para caracterizar as estruturas rifte da Bacia Potiguar (RN/CE), utilizando como principal parâmetro o índice estrutural, que representa um indicador da forma geométrica da fonte anômala. Os melhores resultados foram obtidos com um índice estrutural igual a zero (para as anomalias gravimétricas residuais) e 0,5 (para as anomalias magnéticas reduzidas ao polo), tamanho da janela espacial igual a 10 km, que ´e utilizada para determinar a área que deve ser usada para o cálculo da deconvolução de Euler, e tolerância máxima do erro variando de 0 a 7%, que determina quais soluções são aceitáveis. As nuvens de soluções de Euler nos permitiram caracterizar os principais limites falhados do rifte Potiguar, bem como suas profundidades, mergulho e relações estruturais com o embasamento Pré-cambriano. Palavras-chave: deconvolução de Euler, métodos potenciais, índice estrutural, rifte Potiguar.
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Kuncoro, Henri, Irwan Meilano i Susilo Susilo. "Sunda and Sumatra Block Motion in ITRF2008". E3S Web of Conferences 94 (2019): 04006. http://dx.doi.org/10.1051/e3sconf/20199404006.
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The Southeast Asia region is mostly surrounded by active subduction zones in which the Australian plate, the Indian plate, and the Philippine Sea plate submerges beneath the continental plates and blocks. The Sunda block covers the large part of the Southeast Asia region, which comprises of Indochina, the South China Sea, the northeastern part of Sumatra, Borneo, the northern part of Java, and the shallow seas in between. We collect the GPS data in the whole Southeast Asia region for the period from 1994 to 2016, and process the original carrier phase data of GPS using GAMIT/GLOBK 10.6 to obtain the velocity field in the International Terrestrial Reference Frame, ITRF2008. The velocity field thus obtained is utilized to update the Euler rotation parameters of the Sunda block in ITRF2008, and model the long-term slip rates between the adjacent plate and blocks. In this study, we model the Sunda block and the Sumatra block together with the Australian plate by using TDEFNODE. The estimated Euler pole parameters of the Sumatra and Sunda blocks are estimated as their locations at (37.4°S, 106.8°E) and (46.2°N, 89.4°W), respectively, and their angular velocities of 0.371°/Myr clockwise, and 0.327°/Myr counter clockwise, respectively. These parameters result in the slip rate of the Sumatra fault with magnitude of ~9 mm/yr.
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Kouame, Armel Kouadio, Marc Youan Ta, Bertrand Houngnigbo Akokponhoue, Omer Zéphir De Lasme i Loukou Nicolas Kouamé. "Contribution of Aeromagnetic Data to the Structural Discontinuities Identification of Black Volta Catchment Aquifer System in Côte d'Ivoire". European Scientific Journal, ESJ 19, nr 30 (31.10.2023): 307. http://dx.doi.org/10.19044/esj.2023.v19n30p307.
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This paper focuses on improving the structural knowledge of the fissured aquifers of the Black Volta catchment in Côte d'Ivoire based on the mapping of magnetic lineaments, which represent magnetic discontinuities such as magmatic body contacts or tectonic faults. Four filtering methods, pole reduction (equator), gradient (vertical and hori-zontal), upward extension, and angle tilt, were applied to the residual magnetic field map to extract magnetic discontinuities while using the Oasis Montaj (Geosoft) program. Euler deconvolution coupled with the analytical signal provided, in addition to the horizontal location of the magnetic contacts, is an indication of their depths. The resulting structural map contains 458 structures, with lengths ranging from 9.03 to 66.54 km. Three directions, NW-SE, E-W and NE-SW, were detected with a predominance of the NW-SE direction. Depths estimated by Euler solutions range from 6.8 to 2847 m. This map is consistent with many faults already recognised or assumed by traditional structural studies and tectonic events affecting the Ivorian basement. These results contribute significantly to the improvement of the structural map of the Black Volta Basin in Côte d'Ivoire. In addition to the major known tectonic faults, numerous lineaments, particularly those at depth, have been highlighted by the present study.
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Gerovska, Daniela, Marcos J. Araúzo-Bravo, Petar Stavrev i Kathryn Whaler. "MaGSoundDST — 3D automatic inversion of magnetic and gravity data based on the differential similarity transform". GEOPHYSICS 75, nr 1 (styczeń 2010): L25—L38. http://dx.doi.org/10.1190/1.3298619.
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We present an automatic procedure — Magnetic And Gravity SOUNDing Differential Similarity Transform (MaGSoundDST) — for inversion of regular or irregular magnetic- and gravity-grid data measured on even or uneven surfaces. It solves for horizontal position, depth, and structural index of simple sources and is independent of a linear background. In addition, it estimates the shape of sources consisting of several singular points and lines. The method uses the property of the differential similarity transform (DST) of a magnetic or a gravity anomaly to become zero or linear at all observation points when the central point of similarity of the transform, which we refer to as the probing point, coincides with a source’s singular point. It uses a measured anomalous field and its calculated or measured (gradiometry) first-order derivatives. The method is independent of the magnetization-vector direction in the magnetic data case and does notrequire reduction-to-the-pole transformed data as input. With MaGSoundDST, we provide an important alternative interpretation technique to the Euler deconvolution procedures, combining a moving-window method, whereby the solutions are linked to singular points of causative bodies, with an approach in which the solutions are linked to the real sources. The procedure involves calculating a 3D function that evaluates the linearity of the DST for different integer or noninteger structural indices, using a moving window. We sound the subsurface along a vertical line under each window center. Then we combine the 3D results for different structural indices and present them in three easy-to-interpret maps, avoiding the need for clustering techniques. We deduce only one solution for location and type of simple sources, which is a major advantage over Euler deconvolution. Application to different cases of synthetic and real data shows the method’s applicability to various types of magnetic and gravity field investigations.
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Barbosa Filho, Ricardo, Tatiane Bastos Mangueira de Menezes, Pérola Reis de Souza Dias, Emanuelly Thays Muniz Figueiredo Silva, Kristopherson Lustosa i Fabrício André Martins da Costa. "Apresentação Auto-Imune Rhupus Like de cancer de pulmão de não pequenas células". E-Acadêmica 3, nr 2 (16.06.2022): e4432168. http://dx.doi.org/10.52076/eacad-v3i2.168.
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Rhupus, ou Síndrome Rhupus, é uma doença reumatológica rara caracterizada pela sobreposição de Lúpus Eritematoso Sistêmico e Artrite Reumatóide em pacientes preenchendo critérios de SLICC e ACR/EULAR. Objetivo: Descrever o caso clínico de uma paciente com câncer de pulmão de não pequenas células apresentando quadro clínico compatível com Síndrome Rhupus e realizar revisão bibliográfica sobre Rhupus e sua clínica. Metodologia: Estudo do tipo relato de caso, descritivo, qualitativo com informações obtidas diretamente dos registros médicos realizados durante a internação hospitalar. Discussão: Síndrome Rhupus, caracterizada pela sobreposição de LES e AR, possui duas apresentações mais comuns, a primeira são pacientes que iniciam quadro de AR, e, após, são diagnosticados com LES, compreendendo 2/3 dos casos de Rhupus. A segunda apresentação consiste em pacientes inicialmente com LES ou apresentam as duas doenças diagnosticadas no início do quadro. Tratando-se de uma síndrome rara, não existem critérios diagnósticos validados para esta enfermidade. Conclusão: Embora não rara a interposição de doenças reumatológicas, Rhupus possui prevalência estimada em 0,09% da população. O diagnóstico pode ser dificultado por não existirem critérios diagnósticos bem definidos e pela raridade, porém este diagnóstico pode ser determinante para a abordagem adequada do paciente e melhor prognóstico, reduzindo complicações relacionadas a LES e/ou AR.
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Debona, Luiz Augusto, Dilson Palhares Ferreira, Inácio Carlos Murta Júnior, Thaise Neto Maia, Letícia Rocha Santos Maciel, Evandro Messias Neves Da Silva, Michelly Rodrigues Cavalcante i Ulisses Almeida De Jesus. "ESCLEROSE SISTÊMICA: RELATO DE CASO DE UM DIAGNÓSTICO PRECOCE NA AUSÊNCIA DE FENÔMENO DE RAYNAUD E REVISÃO DE LITERATURA". Revista Contemporânea 4, nr 2 (20.02.2024): e3359. http://dx.doi.org/10.56083/rcv4n2-062.
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A Esclerose Sistêmica (ES) é uma doença autoimune crônica, multissistêmica, progressiva e de apresentação heterogênea envolvendo a pele e vários sistemas orgânicos. É considerada uma doença rara, com incidência anual estimada em 14 casos por milhão de habitantes e prevalência de 35 casos por milhão de habitantes. Tem apresentação clínica variável e pode ser classificada com base na extensão do acometimento cutâneo, associada ao padrão de envolvimento de órgãos e sistemas (gastrointestinal, pulmonar, renal, cardiovascular e musculoesquelético). Os sinais clínicos são diversos, sendo os mais comuns o espessamento e endurecimento da pele, por vezes associado a edema e fenômeno de Raynaud (FRy). Diagnosticar esta condição é um desafio para os médicos devido à sua apresentação diversificada. Para auxiliar no diagnóstico, os critérios de classificação do Colégio Americano de Reumatologia e da Liga Europeia Contra o Reumatismo (ACR/EULAR) de 2013 são usados para orientar o raciocínio diagnóstico. Não existe tratamento curativo para esta condição; o objetivo é prevenir a progressão para estágios avançados de fibrose. Este artigo tem como objetivo revisar o assunto e relatar o diagnóstico precoce de um paciente com ES Cutânea Difusa que apresentou sintomas de edema de dedos, esclerodermia de dedos e membros superiores durante 5 meses na ausência de FRy e que obteve de forma precoce o diagnóstico apesar do padrão incomum de acometimento.
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Arroyo Palomo, J., L. Villalobos-Sánchez, V. García García, V. Aguado Casanova, L. Calvo Sanz, I. Del Bosque Granero, F. J. Huelin Alcubierre, J. J. Gonzalez Lopez i M. Revenga Martínez. "AB0739 PSORIATIC ARTHRITIS RELATED-UVEITIS, OUR EXPERIENCE IN A THIRD-LEVEL SPANISH CENTRE." Annals of the Rheumatic Diseases 79, Suppl 1 (czerwiec 2020): 1665.1–1665. http://dx.doi.org/10.1136/annrheumdis-2020-eular.4835.
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Background:The occurrence of uveitis in patients with psoriatic arthritis (PsA) has been documented as the most frequent and important extra-articular manifestation, with an estimated frequency of 7 and 18%. Clinical onset may be acute or insidious, and it may be accompanied by other ocular manifestations. In contrast with spondyloarthropathy related-uveitis, PsA associated tends to be insidious, bilateral, chronic or posterior.Objectives:To describe clinic and immunological features of psoriatic arthritis patients in our centre, especially those with associated-uveitis and to define its frequency.Methods:A retrospective, descriptive and single-centre study (1985-2017) of 494 patients diagnosed with PsA according to the criteria of an expert rheumatologist was conducted. All patients were studied according to a standard protocol. The group was divided into 3 articular categories: pure axial, pure peripheric and mixed. Data regarding enthesitis and dactylitis, as well as HLA-Cw6 and HLA-B27 were extracted, from those available. Ophthalmologic and cutaneous involvement was registered. 216 patients were excluded because of data absence or alternative plausible diagnosis. Descriptive analyses were applied.Results:Eight patients had uveitis (2,9% in this series), only one case developed chronic pattern. Acute anterior uveitis was the form of presentation in 6 patients (75%). Unilateral involvement was registered in 3 (37,5%), in every case with right eye implication. One patient developed up to 13 episodes of acute anterior uveitis, every episode in the same eye. Median of age at first episode was 54 years, 3 (37,5%) patients were female. Regarding articular categories: 1(12,5%) pure axial, 3 (37,5%) pure peripheric and 4 (50%) mixed. Enthesitis was registered in 2 patients, none of our series developed dactylitis. 3 patients (37,5%) were HLA-B27 positive and 2 patients (25%), HLA-Cw6 positive. 6 cases had cutaneous psoriasis (75%). Adalimumab was prescribed to 5 PsA related-uveitis patients with optimal control of disease.Larger PsA cohort without ocular involvement (270 patients), 118 (42,4%) cases were female and median of age was 44 years. Pure axial involvement was present in 20 (7,2%), pure peripheric, 134 (48,2%) and mixed, 122 (43,8%). 31 (11,15%) cases developed enthesis involvement and 18 (6,5%), dactylitis. HLA-B27 was tested positive in 45 patients (19,7%) and HLA-Cw6, in 56 (27,4%). Cutaneous psoriasis was present in 231 cases (83,1%).Conclusion:Frequency of psoriatic arthritis-uveitis is lower in our sample than referred in bibliography. Further investigations are needed to understand the underlying reasons, although it could be related to the use of biologic treatment and narrower inflammatory activity control in comparison to previous studies. No posterior pole involvement, bilaterality, chronicity nor insidious onset are common in our data; neither axial involvement seems to be predictor for the appearance of uveitis.References:[1]Rosenbaum JT. Uveitis in spondyloarthritis including psoriatic arthritis, ankylosing spondylitis, and inflammatory bowel disease. Clin Rheumatol 2015;34:999-1002.[2]Queiro R, et al. Clinical Features and Predictive Factors in Psoriatic Arthritis–Related Uveitis. Semin Arthritis Rheum 2002;31:264-270.[3]Paiva ES, et al. Characterisation of uveitis in patients with psoriatic arthritis. Ann Rheum Dis. 2000;59(1):67–70.Disclosure of Interests:None declared
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Karimi, Kurosh, i Gunther Kletetschka. "Subsurface geology detection from application of the gravity-related dimensionality constraint". Scientific Reports 14, nr 1 (30.01.2024). http://dx.doi.org/10.1038/s41598-024-52843-5.
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AbstractGeophysics aims to locate bodies with varying density. We discovered an innovative approach for estimation of the location, in particular depth of a causative body, based on its relative horizontal dimensions, using a dimensionality indicator (I). The method divides the causative bodies into two types based on their horizontal spread: line of poles and point pole (LOP–PP) category, and line of poles and plane of poles (LOP–POP) category; such division allows for two distinct solutions. The method’s depth estimate relates to the relative variations of the causative body’s horizontal extent and leads to the solutions of the Euler Deconvolution method in specific cases. For causative bodies with limited and small depth extent, the estimated depth (z^0) corresponds to the center of mass, while for those with a large depth extent, z^0 relates to the center of top surface. Both the depth extent and the dimensionality of the causative body influence the depth estimates. As the depth extent increases, the influence of I on the estimated depth is more pronounced. Furthermore, the behavior of z^0 exhibits lower errors for larger values of I in LOP–POP solutions compared with LOP–PP solutions. We tested several specific model scenarios, including isolated and interfering sources with and without artificial noise. We also tested our approach on real lunar data containing two substantial linear structures and their surrounding impact basins and compared our results with the Euler deconvolution method. The lunar results align well with geology, supporting the effectiveness of this approach. The only assumption in this method is that we should choose between whether the gravity signal originates from a body within the LOP–PP category or the LOP–POP category. The depth estimation requires just one data point. Moreover, the method excels in accurately estimating the depth of anomalous causative bodies across a broad spectrum of dimensionality, from 2 to 3D. Furthermore, this approach is mathematically straightforward and reliable. As a result, it provides an efficient means of depth estimation for anomalous bodies, delivering insights into subsurface structures applicable in both planetary and engineering domains.
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Abbas, Mahmoud Ahmed, Luca Speranza, Maurizio Fedi, Bruno Garcea i Luigi Bianco. "Magnetic data modelling of salt domes in Eastern Mediterranean, offshore Egypt". Acta Geophysica, 23.02.2024. http://dx.doi.org/10.1007/s11600-024-01284-9.
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AbstractWe analyzed magnetic data of a deep-water area in the Eastern Mediterranean, offshore Egypt where there are numerous salt domes. Regional-residual separation of the reduced to pole (RTP) magnetic anomalies was performed with the discrete wavelet transform, and the residual magnetic anomalies were interpreted as mainly due to the susceptibility contrast between sediments and salt bodies. A multiscale boundary analysis of the anomalies yielded meaningful lineaments at both large and short scales. Salt bodies lineaments are very well defined in the short-scale map. Then, we inverted the data by a nonlinear and non-iterative 3D inversion technique, to delineate the salt bodies and estimate their magnetization contrast. We used the depths obtained from the Euler deconvolution to form a set of maxima and minima constraints in the inversion. Our procedure yielded an interesting map of the top of salt in the deep-water region, entirely based on the magnetic data, which agrees well with the seismic top of salt. This is a somewhat surprising result, in some respects not obvious, demonstrating that magnetic prospecting can be an important and low-cost tool for the exploration of salt diapirs, especially when seismic data are partially or completely inaccessible or of poor quality.
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Snay, Richard A., Jeffrey T. Freymueller i Michael L. Dennis. "Modeling 3D crustal velocities in the vicinities of Alaska and the Bering sea". Journal of Applied Geodesy, 27.06.2023. http://dx.doi.org/10.1515/jag-2023-0004.
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Abstract This document introduces Version 0.4 of the TRANS4D software, where TRANS4D is short for Transformations in Four Dimensions. TRANS4D enables geospatial professionals and others to transform three-dimensional positional coordinates across time and among several popular terrestrial reference frames. Version 0.4 introduces new crustal velocity models for the vicinities of Alaska and the Bering Sea, including parts of northwestern Canada and eastern Russia. These new models supplement existing velocity models for the continental United States as well as for most of Canada and for a neighborhood of the Caribbean plate. This document also provides evidence for the existence of a Bering tectonic plate, and it presents estimates for the Euler-pole parameters of this hypothesized plate. Moreover, estimated horizontal velocities computed at several geodetic stations located in Alaska provide evidence for the existence of part of the plate boundary separating the North American plate and the hypothesized Bering plate.
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Allal, Saddam Housseyn, Said Eladj, Hicham Dekkiche, Kamel Hasni i Younes Ahmed Betchim. "Recent Euler pole parameters and relative velocities of the Nubia–Eurasia and Nubia–South America plates estimated using GPS technique". Acta Geophysica, 10.02.2023. http://dx.doi.org/10.1007/s11600-023-01031-6.
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Jarrin, P., J.-M. Nocquet, F. Rolandone, H. Mora-Páez, P. Mothes i D. Cisneros. "Current motion and deformation of the Nazca plate: new constraints from GPS measurements". Geophysical Journal International, 9.09.2022. http://dx.doi.org/10.1093/gji/ggac353.
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Summary We use new GPS data to determine an updated Euler pole describing the present-day motion of the oceanic Nazca plate. Our solution includes continuous GPS (cGPS) measurements at Malpelo Island offshore Colombia, two sites in the Galapagos archipelago, Easter Island and Salas y Gomez Island in the western part of the plate and Robinson Crusoe Island offshore Chile. A careful analysis of geodetic time series reveals that (1) previous estimates using former cGPS site EISL are biased by several mm/yr eastward due to station malfunctioning (2) north velocity component of cGPS site GLPS at Santa Cruz Island in the Galapagos is impacted by volcanic deformation at the 1-2 mm/yr level, probably caused by the recurrent volcanic activity of the Sierra Negra volcano. In addition, we find shortening at ∼1 mm/yr between Easter Island (cGPS ISPA) and Salas y Gomez Island (cGPS ILSG), consistent with the elastic deformation induced by rapid opening at the East Pacific rise. cGPS site at Robinson Crusoe Island shows ∼4-5 mm/yr abnormally fast East velocity induced by the visco-elastic relaxation following the Maule Mw 8.8 2010 earthquake. Using this information, we determine a new Euler pole (longitude: -90.93○E, latitude 56.19○N, 0.588 deg/Myr) describing the present-day Nazca/South America plate motion, using 5 sites (Malpelo Island, two sites in the Galapagos archipelago, Easter Island and Salas y Gomez Island). The proposed Euler pole provides a weighted root mean square (wrms) of residual velocities of 0.6 mm/yr, slightly higher than usually observed for other major tectonic plates and accounting for the uncertainty of potential volcanic/tectonic deformation. Our model predicts a maximum convergence rate at 65.5 ± 0.8 mm/yr at latitude ∼30○S along the Chile trench, decreasing to 50.8 ± 0.7 mm/yr in northern Colombia and 64.5 ± 0.9 mm/yr in southern Chile (1-σ confidence level). Comparison with the geological models NUVEL1A and MORVEL indicates constant decrease since 3.16 Ma of opening rate along the Nazca/Antarctic plate boundary spreading centers at ∼1 cm/yr per Myr. Combined with the ITRF2014 pole for the Pacific and Antarctic plates, our derived Euler pole predicts closure at the ∼1 mm/yr level for Pacific/Antarctic/Nazca plate circuit. However, combining our results with MORVEL estimates for the Cocos plate, the non-closure of the Pacific/Cocos/Nazca plate circuit is 9.7 ± 1.6 mm/yr, 30 per cent lower than the 14 ± 5 mm/yr reported in MORVEL model, but still significant. A small (∼1.5 mm/yr) velocity residual at Malpelo Island neither supports the hypothesis of an independent Malpelo microplate offshore Colombia nor large scale internal deformation induced by thermal contraction. Our solution rather suggests that non-closure of the Pacific/Cocos/Nazca plate circuit arises from the determination of the Cocos plate motion in MORVEL, an hypothesis further supported by the large discrepancy between MORVEL’s prediction and the observed GPS velocity observed at Cocos Islands (cGPS ISCO).
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Tawey, Mam D., Abbass A. Adetona, Usman D. Alhassan, Abdulwaheed A. Rafiu, Kazeem A. Salako i Emmanuel E. Udensi. "Edge Detection and Depth to Magnetic Source Estimation in Part of Central Nigeria". Physical Science International Journal, 9.09.2020, 54–67. http://dx.doi.org/10.9734/psij/2020/v24i730203.
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High-resolution aeromagnetic data covering an area of 24, 200 km2 in north central Nigeria has been acquired and analyzed with the aim of carrying out trend analysis, edge detection (structural delineation) and depth to magnetic source estimation using reduce to the pole (RTP), horizontal gradient magnitude (HGM), center for exploration targeting plug-in (CET), 3D Euler deconvolution and source parameter imaging (SPI) techniques. Trend analysis was applied to the RTP data to delineate structures that have dissected the area. The 3D Euler deconvolution and HGM were correlated by plotting the estimated Euler solutions for a structural index of one (SI=1) on HGM map and the resulting map produced have shown that both methods can contribute in the interpretation of the general structural framework of the study area. The structural delineation based on HGM and CET maps showed that two predominant trends (ENE-WSW) and (WNW-ENE) have affected the area. The trend/depth/contacts of these faults were classified into four groups: Faults <150 m, 150 m - 300 m, 300m - 450 m which are the most predominant fault system based on Euler solutions with a structural index of one (SI=1) and those deeper than 450 m while the result of source parameter imaging (SPI) revealed a depth to source varying from 58 m specifically for areas with shallow depth to the magnetic source to those from deeper source occurring at 588.153m depth especially the south-central portion and the south-eastern portion of the study area.
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"Characterization of the Microstructure of A Breakout Steel Sample". Journal of Applied Material Science & Engineering Research 7, nr 2 (13.11.2023). http://dx.doi.org/10.33140/jamser.07.02.12.
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The microstructure of a continuously cast break out of low carbon steel has been studied using optical microscopy; SEM/EDS and EBSD analysis techniques. SEM and EBSD studies were carried out on two different locations on one sample piece and the resulting room temperature grains were found to be mostly BCC α- ferrite phase. Their orientations (using Euler angles) were determined. No meaningful amount of FCC phase was indexed after two patterns indexed on the two locations of the sample piece. The FCC comprised only 0.02% to 0.08% of the total patterns indexed. EBSD maps for the two locations, along with pole figures and grain size charts were deduced for the BCC phase. Volume fraction of the phase was estimated. Reconstruction of the Prior Austenite Grain Boundary was made from the alpha grains data using AztecWave software (AZtecCrystal). Only a small amount of the prior austenite grain boundaries was determined suggesting that the size of the parent grains were significantly larger than the map area in each case.
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Eshanibli, Abdelhakim S., Abel Uyimwen Osagie, Nur Azwin Ismail i Hussin B. Ghanush. "Analysis of gravity and aeromagnetic data to determine structural trend and basement depth beneath the Ajdabiya Trough in northeastern Libya". SN Applied Sciences 3, nr 2 (27.01.2021). http://dx.doi.org/10.1007/s42452-021-04263-7.
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AbstractIn this study, we analyse both ground gravity and aeromagnetic data in order to delineate structural trends, fault systems and deduce sedimentary thicknesses within the Ajdabiya Trough in Libya’s northeast. A high-pass filter and a reduced-to-the-pole (RTP) transformation are applied to the gravity and aeromagnetic data respectively. Different filters are used to enhance the structural signatures and fault trends within the study area. The Werner deconvolution and source parameter imaging (SPI) techniques are applied to the RTP magnetic data for source depth estimation. Four well-data within the area are used as constraints in the two-dimensional forward modelling process. The results show that the Ajdabiya Trough is characterised by gravity anomaly highs and magnetic anomaly lows. The analysis of gravity data shows predominant Northeast–Southwest structural trends, whereas the analysis of magnetic data shows predominant North–South magnetic lineaments within the Ajdabiya Trough. The Euler deconvolution depth estimates of faults depths range between 1500 and 9500 m. The SPI estimates of the magnetic basement range between 2500 and 11,500 m beneath the study area (deepest beneath the Ajdabiya Trough). Constrained by the well-data, six major layers characterize the four profiles that are taken within the area. One of the profiles shows a high-density intrusion (about 4 km from the surface) within the sedimentary sequence. The intrusion may be the result of the rifting Sirt Basin which caused a weakening of the crust to allow for mantle intrusion.
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Khalil, Ahmed, Tharwat H. Abdel Hafeez, Ahmed El kotb, Hassan S. Saleh, Waheed H. Mohamed i Emad Takla. "Subsurface structural characterization as deduced from potential field data—West Beni Suef, Western Desert, Egypt". Arabian Journal of Geosciences 15, nr 21 (19.10.2022). http://dx.doi.org/10.1007/s12517-022-10900-1.
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AbstractThe goal of present study is determining subsurface structural elements by analyzing geomagnetic data sets aiming to examine their impacts on geological surface structures characterizing the western region in Beni-Suef Governorate, Western Desert, Egypt. A land-magnetic survey is conducted by two exceedingly sensitive proton magnetometers to measure the total intensity of geomagnetic field at the region under investigation. The measurements of regional gradients and time variation were applied to get the required reduction of daily variation. The regional expansions of subsurface structural units were obtained after applying the reduction to north magnetic pole (RTP) method to the corrected magnetic data acquired from land-magnetic survey along with Bouguer maps (1:100,000 scale and 1-mGal contouring interval). Regional-residual technique was applied depending on the power spectrum analysis. Moreover, the edge detection approach is conducted to depict the structures and subsurface hidden anomalies. Different handling processes were applied for acquired land magnetic datasets such as Euler deconvolution and trend analysis. The results of current study revealed that four significant structural forces across the N-S, NW–SE, NE-SW, and E-W directions affected the region. Estimating the basement depth was accomplished using a number of spectral analysis techniques. The values of estimated depths are used for creating a basement relief map. Moreover, the achieved results show that depths to the basement at the region under study vary between 2.3 and 4.7 km.
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Lei, Yu, Liguo Jiao, Jiyao Tu, Junhao Zhao i Qinghua Huang. "Magnetic Structure and its Tectonic Implication Around Longmenshan Fault Zone Revealed by EMAG2v3". Frontiers in Earth Science 10 (4.03.2022). http://dx.doi.org/10.3389/feart.2022.848824.
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The formation of magnetic minerals is bound up with the tectonic evolution history, whereupon the distribution of magnetic anomalies has great meanings for regional tectonics. In this study, we use the latest global lithospheric magnetic field model EMAG2-v3, processed by various techniques including reduction to the pole (RTP), upward continuation, derivations, Euler deconvolution, estimation of total magnetization direction, and Curie point depth (CPD), to unveil the tectonics around Longmenshan fault zone (LFZ). LFZ is clearly displayed as a positive and negative anomaly transition zone in RTP anomalies and acts as a magnetic basement boundary. The Sichuan Basin (SB), located to the east of LFZ, is marked by strong magnetic basement and NE-strike banded induced positive anomalies which are associated with the Neoproterozoic magmatic activity. The banded shape, absence of radial pattern of anomalies, and existence of fossil subduction zone supports that the magnetic basement was formed in arc environment. The CPD in SB estimated by radial average power spectral is 30–51 km, which allows magnetic minerals in deep crust or even in lithospheric mantle to exhibit high magnetizations. The Songpan-Ganzi fold belt (SGFB), in contrast, is located to the west of LFZ and covered by thick and low-susceptibility Triassic deposits of flysch, manifests as weak negative anomalies caused by relatively shallow CPD and widespread remanent magnetization. Significant positive anomalies, appearing around the Manai and Rilonguan granitic massifs, indicate a strong magnetic basement beneath SGFB, which is conjectured as westward extension of the Yangtze Block at depth.