Academic literature on the topic '3D gravity model'
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Journal articles on the topic "3D gravity model"
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Zapata, José A. "Continuum spin foam model for 3d gravity." Journal of Mathematical Physics 43, no. 11 (November 2002): 5612–23. http://dx.doi.org/10.1063/1.1509850.
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Sedrakyan, A. G. "3D Ising model and 2D induced gravity." Physics Letters B 260, no. 1-2 (May 1991): 45–52. http://dx.doi.org/10.1016/0370-2693(91)90967-u.
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Sun, Siyuan, Changchun Yin, and Xiuhe Gao. "3D Gravity Inversion on Unstructured Grids." Applied Sciences 11, no. 2 (January 13, 2021): 722. http://dx.doi.org/10.3390/app11020722.
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Compared with structured grids, unstructured grids are more flexible to model arbitrarily shaped structures. However, based on unstructured grids, gravity inversion results would be discontinuous and hollow because of cell volume and depth variations. To solve this problem, we first analyzed the gradient of objective function in gradient-based inversion methods, and a new gradient scheme of objective function is developed, which is a derivative with respect to weighted model parameters. The new gradient scheme can more effectively solve the problem with lacking depth resolution than the traditional inversions, and the improvement is not affected by the regularization parameters. Besides, an improved fuzzy c-means clustering combined with spatial constraints is developed to measure property distribution of inverted models in both spatial domain and parameter domain simultaneously. The new inversion method can yield a more internal continuous model, as it encourages cells and their adjacent cells to tend to the same property value. At last, the smooth constraint inversion, the focusing inversion, and the improved fuzzy c-means clustering inversion on unstructured grids are tested on synthetic and measured gravity data to compare and demonstrate the algorithms proposed in this paper.
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Wang, Peng, Jie Zhang, and Ning Huang. "An Idealized 3D Model of Interfacial Instability of Aeolian Bedform." Applied Sciences 11, no. 19 (September 26, 2021): 8956. http://dx.doi.org/10.3390/app11198956.
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An idealized morphodynamic model is constructed for formation of the aeolian sand ripples from small bottom perturbations of a two-dimensional sand bed. The main goal of the analysis is to evaluate the influence of the gravity flow (including “impact-induced gravity flow” in the reptation flux and “topography-induced gravity flow” in the creep flux) on the formation of the aeolian sand ripples and to clarify the relative contribution of various factors to the bed instability. A 3D linear stability analysis reveals that gravity flow appreciably affects the dynamics behaviors of aeolian sand ripples, which decreases the growth rate of sand ripples, tends to stabilize the sand bed, and leads to longer wavelength. We found that the competition between the destabilizing effect of reptation flow and the stabilizing effects of gravity flow leads to pattern selection. The along-crest diffusion of topography driven by impact and gravity is beneficial to the transverse stability of sand ripples, producing sand ripples with straighter and more continuous crests. For moderate values of D, the most unstable mode has zero value of the transverse wavenumber (ky = 0), thus corresponding to aeolian ripples with crests perpendicular to the wind. Moreover, when the impact angle is 9–16°, it has little effect on the characteristics of sand ripples for the initial stage of ripple development. For every increase of the impact angle by 1°, the initial wavelength only increases by about 1.5%. In conclusion, the influence of the gravity flow on the dynamics of sand ripples formation stage cannot be neglected.
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BOULATOV, D. V. "A MODEL OF THREE-DIMENSIONAL LATTICE GRAVITY." Modern Physics Letters A 07, no. 18 (June 14, 1992): 1629–46. http://dx.doi.org/10.1142/s0217732392001324.
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A model is proposed which generates all oriented 3D simplicial complexes weighted with an invariant associated with a topological lattice gauge theory. When the gauge group is SUq(2), qn=1, it is the Turaev-Viro invariant and the model may be regarded as a nonperturbative definition of 3D simplicial quantum gravity. If one takes a finite Abelian group G, the corresponding invariant gives the rank of the first cohomology group of a complex C:IG(C)=rank(H1(C,G)), which means a topological expansion in the Betti number b1. In general, it is a theory of the Dijkgraaf-Witten type, i.e., determined completely by the fundamental group of a manifold.
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ARIAS, PIO J., ADEL KHOUDEIR, and J. STEPHANY. "MASTER ACTIONS FOR LINEARIZED MASSIVE GRAVITY MODELS IN 3D." International Journal of Modern Physics A 27, no. 03n04 (February 10, 2012): 1250015. http://dx.doi.org/10.1142/s0217751x12500157.
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We present a unified analysis of the self-dual, second order, topologically massive and the recently introduced fourth-order models of massive gravity in 3D. We show that there is a family of first-order actions which interpolate between these different single excitation models. We show how the master actions are related by duality transformation. We construct by the same method the master action which relates the fourth-order new massive model with two excitations and the usual second-order model with Fierz–Pauli mass. We show that the more general model obtained by adding a Chern–Simons term to the new massive model is equivalent off-shell to the second-order spontaneously broken linearized massive gravity.
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MARTELLINI, MAURIZIO, and MARIO RASETTI. "(2+1)-DIMENSIONAL QUANTUM GRAVITY AND THE 3D-ISING MODEL." International Journal of Modern Physics B 10, no. 18n19 (August 30, 1996): 2217–48. http://dx.doi.org/10.1142/s021797929600101x.
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We show that (2+1)-dimensional Euclidean quantum gravity is equivalent, under mild topological assumptions, to a Gaussian fermionic system. Furthermore we argue that the corresponding (2+1)-dimensional Euclidean quantum gravity partition function may be related to the partition function of the reduced 3D-lattice Ising model for finite lattices.
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Chasseriau, Pierrick, and Michel Chouteau. "3D gravity inversion using a model of parameter covariance." Journal of Applied Geophysics 52, no. 1 (January 2003): 59–74. http://dx.doi.org/10.1016/s0926-9851(02)00240-9.
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Qiang, Jianke, Jing Xu, Kai Lu, and Zhenwei Guo. "A Fast Forward and Inversion Strategy for Three-Dimensional Gravity Field." Mathematics 11, no. 4 (February 13, 2023): 962. http://dx.doi.org/10.3390/math11040962.
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Obtaining a three-dimensional (3D) density distribution within a reasonable time is one of the most critical problems in gravity exploration. In this paper, we present an efficient 3D forward modeling and inversion method for gravity data. In forward modeling, the 3D model is discretized into multiple horizontal layers, with the gravity field at a point on the surface being the sum of the gravity fields from all layers. To calculate the gravity field from each horizontal layer, we use the fast Fourier transform (FFT) method and the Block Toeplitz with Toeplitz Blocks (BTTB) matrix, which dramatically reduces both the computation time and storage requirement. In the inversion, the observed gravity data are separated into multiple gravity components of different depths using the cutting separation method. An iterative method is used to adjust the model to fit the above gravity component for each cutting radius. The initial model is constructed from the transformation of gravity components. These methods were applied to both synthetic data and field data. The numerical simulation validated the proposed methods, and the inversion results of field data were consistent with information obtained from well logging. The computational time and memory usage were also reasonable.
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Geng, Meixia, Danian Huang, Qingjie Yang, and Yinping Liu. "3D inversion of airborne gravity-gradiometry data using cokriging." GEOPHYSICS 79, no. 4 (July 1, 2014): G37—G47. http://dx.doi.org/10.1190/geo2013-0393.1.
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We developed a new method for interpretation of airborne gravity gradiometry data, based on cokriging inversion. The cokriging method that we evaluated minimized the theoretical estimation error variance by using auto- and crosscorrelations of several variables. It does not require iterations and can easily include complex a priori information. Moreover, the smoothing effects in the inverted density structure model can be reduced to a certain extent due to the anisotropy constrain in the covariance model. We compared the recovered models obtained by inverting the different combinations of gravity-gradient components to understand how different component combinations contributed to the resolution of the recovered model. The results indicated that including multiple components for inversion increased the resolution of the recovered density model and improved the structure delineation. Moreover, in the case in which the parameters of the variogram model are not well chosen, cokriging with multicomponent combinations can still correctly recover the geometry of the targeted sources. The survey data of the Vinton dome were considered as a case study. The results of the inversion were in good agreement with the known formation in the region. This supports the validity of our method.
Dissertations / Theses on the topic "3D gravity model"
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Umeda, Naoya. "Critical behavior of the matrix models generating 3D random volumes." Kyoto University, 2018. http://hdl.handle.net/2433/232234.
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Yehuwalashet, Ezra. "Gravity and Magnetic Survey, Modelling and Interpretation in the Blötberget Iron-Oxide Mining Area, Bergslagen, Sweden." Thesis, Uppsala universitet, Geofysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-305964.
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The Blötberget mining area, the focus of this MSc project, is located about 230 km northwest ofStockholm and 12 km southwest of the city of Ludvika (central Sweden). The mining area has beenknown since 1600 for its various types of mineralization particularly iron-oxide deposits (magnetite andhematite) with the mining commenced in 1944. Previous geoscientific research in the area providesdetailed information about lithological variations and structure of the bedrock near the surface.However, knowledge of the depth extent of the mineral deposits and their host rocks is limited. To shedlights on these issues and support deep mineral exploration potential in the study area, within the recentlylaunched StartGeoDelineation project, new ground gravity data, 180 data points on average 150 m apart,were collected during two field campaigns in 2015 and 2016. Aeromagnetic data were obtained fromthe Geological Survey of Sweden (SGU) to complement the ground gravity measurement interpretationsand modelling. After a careful inspection of the field gravity data, they were reduced to completeBouguer anomaly with a maximum error estimate of about 0.6 mGal due to uncertainty in theinstrumental drift, slab density, geodetic surveying, diurnal variations and terrain (or topography)correction. The Bouguer gravity data after separation of regional field (second order polynomial at theend was used) were used (~ 8 mGal range) for interpretation and 3D inverse modelling. Clear anomalouszones are noticeable in the gravity data particularly due to mineralization and a major boundaryseparating a gravity low from gravity high in the southern part of the study area likely representing afault boundary separating two different lithological units. In my study, both forward and inversemodelling using rudimentary objects/shapes and voxel-type (mesh) approach were carried out. Effect ofinitial and reference models were tested on both gravity and magnetic datasets. While the constrainedmodels have still significant ambiguity, they help to suggest structural control on the location ofmineralization and may allow estimating an excess tonnage due to the presence of mineralization in thestudy area. Due to access limitations (e.g., unable to measure on the water-filled pit) the gravity modelis sensitive to the measuring positions and constraints using known shape of mineralization was not atthe end successful to overcome this. Collecting more gravity data on the target area and repeated test of3D inversion by adjusting the inversion parameters might help to improve the final result.Gruvområdet Blötberget som denna MSc avhandling är fokuserat kring ligger 230 km från Stockholm,12 km från Ludvika, i Bergslagen. Mineralförekomster, framförallt järnmalm (magnetit och hematit)har varit kända i området sedan 1600-talet, och storskalig brytning inleddes år 1944. Tidigare geologiskaundersökningar i området har gett detaljerad information om fyndighetens ytnära litologi och struktur.Hur långt ner förekomsten och moderbergarten sträcker sig har dock varit okänt. Som del av detnystartade projektet StartGeoDelineation utfördes marknära gravimetrimätningar. Totalt 180 mätpunkter,med ett medelavstånd av 150 m, samlades in under två fältkampanjer under 2015 och 2016.Vid modellering komplementades gravimetridata med magnetometridata, insamlad under flygmätningarutförda av Sveriges geologiska undersökningar (SGU). Efter noggrann bearbetning av gravimetridatatogs den kompletta bougeranomalin fram. Det uppskattade felet är ca 0.6 mGal och är till följd avosäkerhet i korrigeringar för drift hos instrument, dygnsvariation, geodesi och topografi. Efter korrigeringav regional trend (uppskattad från 2:a ordningens pylonom, och med satt skala av 8 mGal somresultat) gjordes en 3D modell, via inversionsalgoritmer, samt en tolkning. Det står klart av framförallti gravimetridatan att det finns två avvikande zoner. Dessa indikerar mineraliseringen och en gräns i densödra delen av undersökningsområdet med gravimetridata i låg respektive höga värde. Detta återspeglartroligtvis också en förkastningszon mellan två lithologiska enheter. I denna studie har enkla geometriskaformer och voxlar (mesh) använts för bådadera forward modellering och inversionsalgoritmer. Deursprungliga och referensmodellerna testades på både dataset för gravitmetri och magnetometri. Trotsatt modellerna fortfarande visar tvetydiga resultat så kan de ändå användas för att ge förslag på struktureroch läge för mineraliseringen, och skall även kunna användas för att uppskatta tonnage. Det sistnämndakunde dock inte uppnås då punktäthet i mätdatan, till följd av att det numera vattenfyllda dagbrottet intekunde inkluderas i mätområdet, och att formen av mineraliseringen inte kunde avgränsar på etttillfredsställande sätt. För en förbättring av resultaten bör fler mätpunkter till gravimetridata samlas in iområdet så att 3D-modelleringen kan förbättras genom upprepade justeringar av inversionsparametrarna
StartGeoDelineation
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Reis, Augusto César Dias dos. "Aplicação da teoria de representação do grupo SU(2) a um modelo de gravitação quântica em 3D." reponame:Repositório Institucional da UFABC, 2016.
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Orientador: Prof. Dr. Rodrigo FresnedaDissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Matemática , 2016.
O modelo de Ponzano-Regge é um modelo de gravitação quântica em três dimensões. O principal objetivo deste trabalho é apresentar os fundamentos para construção desse modelo. Buscamos introduzir conceitos necessários para entendê-lo, abordando a teoria de representações de grupos de Lie compactos, tais como: redutibilidade de uma representação, representações de produto direto, e representações no espaço de funções. Tratamos especialmente do caso particular do grupo SU(2). Nesse contexto particular, apresentamos os símbolos 3j e 6j e suas propriedades. O modelo de Ponzano-Regge descreve uma geometria tridimensional discretizada, dada em termos de uma triangulação por simplexos (tetraedros, em três dimensões), de tal forma que o comprimento de cada aresta corresponde a uma representação irredutível do grupo de Lie SU(2). Estes tetraedros são descritos como símbolos 6j, cuja fórmula assintótica possibilita a passagem ao limite clássico, levando a uma expressão para a função de partição que representa uma soma sobre geometrias em três dimensões.
The Ponzano-Regge model is a quantum gravity model in three dimensions. The main goal of this work is to present the foundations for the construction of this model. We aim at introducing the necessary concepts to understand it, taking into account the theory of representations of compact Lie groups, such as: reducibility of representations, direct product representations, and representations in function spaces. We treat the particular case of the SU(2) group. In this special case, we present the 3j and 6j symbols and their properties. The Ponzano-Regge model describes a discretized 3-geometry, given in terms of a triangulation through simplices (tetrahedrons, in 3 dimensions), such that the length of each edge corresponds to an irreducible representation of the Lie group SU(2). These tetrahedrons are described as 6j symbols, whose asymptotic formula allows taking the classical limit, leading to an expression of the partition function that represents a sum over 3-geometries.
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Bomfim, Everton Pereira. "O uso dos dados da missão GOCE para a caracterização e a investigação das implicações na estrutura de densidade das Bacias Sedimentares do Amazonas e Solimões, Brasil." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/14/14132/tde-21062013-003455/.
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A maneira mais direta de detectar as anomalias da densidade é pelo estudo do potencial gravitacional e de suas derivadas. A disponibilidade global e a boa resolução dos dados do satélite GOCE, aliadas à disponibilidade de dados de gravimetria terrestre, são ideais para a comparação e classificação das bacias de larga escala, como as bacias sedimentares do Solimões e do Amazonas dentro do Craton amazônico. Foram processados um conjunto de dados, produtos GOCE EGG_TRF_2 Level 2, ao longo das trajetórias do satélite para remover o ruído (shift/drift) nos gradientes da gravidade a partir da técnica crossover (XO). Calculamos a redução das massas topográfica a fim de obter os componentes do gradiente da gravidade e anomalia da gravidade usando modelagem direta com prismas esféricos a partir do modelo de elevação digital, ETOPO1. Desta maneira, a comparação dos dados somente do satélite GOCE com as reduções das massas topográficas referentes aos componentes do gradiente da gravidade permitiram estimar quantidades invariantes que trouxeram uma melhoria na interpretação dos dados do tensor de gravidade. Além disso, comparamos dados terrestres do campo de gravidade com dados do campo de gravidade dos modelos geopotenciais EGM2008 e GOCE, uma vez que os dados terrestres podem ser afetados por erros em longos comprimentos de onda devido a erros de nivelamento, diferentes referenciais de altitudes, e aos problemas em interligar diferentes campanhas de medidas da gravidade. Portanto, estimamos uma melhora e uma nova representação dos mapas das anomalias de gravidade e do tensor gradiente da gravidade nas áreas inacessíveis do Craton Amazônico. As observações forneceram novas entradas para determinar campos regionais a partir dados brutos pre-processados (gradiente de gravidade EGG_TRF_2 L2), bem como a partir de um modelo geopotencial mais recente até grau e ordem 250 dos harmonicos esféricos derivados de dados somente do satélite GOCE para a representação do campo de gravidade como geóide, anomalias da gravidade e os componentes tensor da gravidade, os quais foram quantidades importantes para interpretação, modelagem e estudo dessas estruturas. Finalmente, obtivemos um modelo isostático considerando a estrutura de densidade litosférica estudada através de uma modelagem direta 3D da distribuição de densidade por prismas esféricos usando a geometria do embasamento e descontinuidade do Moho. Além do que, constatamos através da modelagem direta das soleiras de diabásios dentro dos sedimentos mostramos que somente as soleiras dentro da Bacia do Amazonas não são as únicas responsáveis pela anomalia de gravidade positiva que coincide aproximadamente com as espessuras máximas dos sedimentos da Bacia. Talvez, isso possa ser também um resultado de movimentos relativos do Escudo das Guianas situado ao norte da Bacia, e o Escudo Brasileiro situado ao sul. Embora isso seja apenas uma evidência adicional preliminar, não podemos confirmá-las a partir das estimativas do campo da gravidade. Portanto, é necessário outros tipos de dados geofísicos, como por exemplo, evidências mais claras advindas do paleomagnetismo.The most direct way to detect density anomalies is the study of the gravity potential field and its derivatives. The global availability and good resolution of the GOCE mission coupled with the availability of terrestrial gravity data are ideal for the scope of intercomparison and classification of the two large-scale Amazon and Solimoes sedimentary basins into area of the Amazon Craton. The GOCE data set obtained in satellite tracks were processed from EGG_TRF_2 Level 2 Products generated with the correction needed to remove the noise (shift/drift), and so, to recover the individual components of the gravity gradient tensor using the crossover (XO) points technique. We calculated the topographic masses reductions in order to obtain the gravity gradient components and gravity anomaly (vertical component) using forward modelling from tesseroids from Digital Elevation Model, ETOPO1. Thus, the comparison of the only-satellite GOCE data with the reductions of the topographic masses for the gradient components allowed to estimate invariants quantities for bring an improvement in the interpretation of the gravity tensor data. Furthermore, we compared the terrestrial data gravity field with EGM2008 and GOCE-deduced gravity field because the terrestrial fields may be affected by errors at long wavelengths due to errors in leveling, different height references, and problems in connecting different measurement campaigns. However, we have estimated an improvement and new representations of the gravity anomalies maps and gravity gradient tensor components primary in inaccessible areas of the Amazon Craton. GOCE observations provide new inputs to determine the regional fields from the preprocessed raw data (EGG_TRF_2 L2 gravity gradients), as well from the most recent global geopotential model available up to degree and order 250 developed in spherical harmonics derived only-satellite GOCE data for representing of geoid and others gravity field as gravity anomaly and gravity gradient tensor components, which are important quantities for modelling and studying these structures. Finally, we obtained the isostatic model considering the lithospheric density structure studied through a 3D direct modelling of density distribution using the geometry of basement and Moho discontinuity, assumed to be known as initial constraint. In addition, we found through direct modeling sills and sediment has shown that the diabase sills are not the only ones responsible for positive gravity anomaly map that transects the Amazon Basin, roughly coincident with the maximum thickness of sedimentary rocks or the trough of the basin. Maybe, this could be the result of the relative movements of the Guiana Shield, situated at the north of the Amazon basin, and the Brazilian Shield, situated at the south. Although this is only a preliminary additional evidence, we cannot confirm it only from the data of gravity. It is necessary others types of geophysical data, for example, more clear evidences obtained from paleomagnetism.
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Chen, Liang. "Dynamical microstructure formation in 3D directional solidification of transparent model alloys : in situ characterization in DECLIC-DSI under diffusion transport in microgravity." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4363/document.
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Afin de clarifier et caractériser les mécanismes fondamentaux de formation des réseaux étendus cellulaires et dendritiques en régime diffusif, des expériences de solidification dirigée permettant l’observation in situ en temps réel de l’interface solide-liquide d’un alliage transparent ont été réalisées dans l’instrument « DECLIC-DSI» à bord de la Station Spatiale Internationale. Des procédures spécifiques d'analyse d'images ont été développées pour caractériser les réseaux et extraire des données de référence à comparer aux modèles théoriques ou numériques. Les mécanismes d’évolution et de sélection de l'espacement primaire sont décrits et reliés à la courbure macroscopique de l'interface qui apparait comme un paramètre important de la dynamique de réseau. L’obtention de réseaux homogènes étendus nous a permis d'observer des instabilités secondaires du régime cellulaire pour la première fois dans des systèmes tridimensionnels: Oscillation et multiplet structure. Nos analyses mettent en évidence l'absence de cohérence globale de l’oscillation, exceptée dans des zones localement ordonnées dans lesquelles les oscillations de cellules voisines peuvent être synchronisées. Dans une autre gamme de paramètres de contrôle, la formation de multiplets -autre type d'instabilité secondaire- a été observée. La structure et la dynamique de ces multiplets est décrite. Enfin, des essais comparatifs ont été réalisés au sol, pour les mêmes paramètres de croissance, afin de clarifier l'influence de la convection. Les différences entre les expériences au sol et en microgravité, en particulier concernant l'espacement primaire, sont reliées à l'amplitude de la convectionTo clarify and characterize the fundamental physical mechanisms active in the formation of three-dimensional (3D) arrays of cells and dendrites, in situ monitoring of series of experiments on a transparent alloy was carried out under low gravity in the DECLIC-DSI on-board the International Space Station. Image analysis procedures have been developed to characterize the patterns and get benchmark data to compare with theoretical or numerical modelling. The mechanisms of primary spacing evolution and selection are described and related to the macroscopic interface curvature that appeared to be a critical parameter. The extended homogeneous patterns obtained in microgravity enabled us to observe secondary instabilities of the cellular pattern for the very first time in 3D patterns: cell oscillation and multiplet structure. Our analyses highlight the absence of global coherence of cell oscillations, except in locally ordered areas where synchronization of neighbor cells may happen. In another range of control parameters, another type of secondary instability has been identified that corresponds to multiplet formation; the structure and dynamics of those multiplets are also described. Finally, comparative experiments have been performed on ground with similar growth parameters to point out the influence of convection. The differences between ground and microgravity results, especially regarding the primary spacing, are related to fluid flow magnitude
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Di, Nezza Maria. "Struttura e Dinamica del Distretto Vulcanico dei Colli Albani da misure gravimetriche:implicazioni geodinamiche e vulcanologiche." Thesis, 2007. http://hdl.handle.net/2122/11864.
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In 2005-2006 in the framework of an INGV-DPC projects, in co-operation with the University of Rome “La Sapienza”, a gravity research started in the Colli Albani Volcanic District aimed:
i) to realize a new gravity network to detect gravity changes due to mass redistribution in the underground inferred by the local volcanic activity;
ii) to upgrade the already available Bouguer gravity map by means of new stations and to carry out new analyses and interpretations to outline a more detailed structural setting of the area.
The gravity network has been designed so as to incorporate an old net of 7 stations, settled in 1981 by the same University group and periodically reoccupied until 2004. The new network is presently formed by 30 stations covering the whole volcanic area and all close to levelling benchmarks to remove the effect of the vertical ground movements. Taking into account the logistic situation of the area, three absolute gravity stations have been settled. Two of them have been located out of the volcanic area to be adopted as references (Sant'Angelo Romano and Palestrina). The third ones has been realized inside the most active part of the volcanic district to calibrate in future (Castel Gandolfo), through its repetition, the gravity changes detected by relative measurements. In the absolute sites the measurements of the vertical gravity gradient have been carried out because g is not directly measured on the ground. Each absolute station is completed with an external satellite ones, then included in the relative network, where the absolute value of g has been also transported through relative measurements. Moreover, 13 selected stations are also sites of vertical gravity gradient measurements. Those measurements helpful to reduce the effect of height changes on gravity variations and their space distribution is useful to reduce the prospecting gravity data. Four surveys of both relative and gradiometric measurements has been carried out (March and June 2006 - January and June 2007).
In order to outline a more structural setting of the investigated area, a new set of about 900 new prospecting gravity stations have been settled inside an old survey made by 1500 stations measured partly by the Servizio Geologico d’Italia (SGI) in 1969 and partly by the University of Rome in 1995. Up today, the new stations have been partly measured and all the available data have been reprocessed and uniformed.
The results from both the dynamics and the static gravimetry will be presented and discussed.
3-D density model of the Colli Albani Volcanic District was obtained. Based on its volcano-tectonic evolution, we interpret volcanic structures that have never been imaged before.Dipartimento di Scienze della Terra Università Sapienza di Roma
Unpublished
1V. Storia eruttiva
2V. Struttura e sistema di alimentazione dei vulcani
4V. Dinamica dei processi pre-eruttivi
5V. Dinamica dei processi eruttivi e post-eruttivi
6V. Pericolosità vulcanica e contributi alla stima del rischio
2SR. VULCANI - Servizi e ricerca per la Società
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Cocchi, L. "Magnetic structural evidences of the 41° parallel zone (Tyrrhenian Sea) inferred from potential field data: the 3D model of the discontinuity." Thesis, 2007. http://hdl.handle.net/2122/4561.
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Potential field data hold a leading role in the geologic-structural
application. Their use becomes even more important if applied
to extremely inaccessible zones as oceanic basins or no-antropized area. By an
areo-naval survey it is possible to cover large areas, in a short time, to
define their deep crustal features that are otherwise not accessible
by other direct methods. The analysis of the magnetic field data is
particularly
effective in the study of the crustal portions characterized by lateral
variation of the magnetic susceptibility. The magnetic analysis is often
applied to areas where sub-volcanic bodies or relic portion of
oceanic nature in sedimentary deposits are located.
The aim of this thesis is the development of a tridimensional model about
the 41st parallel zone starting from potential field data.
The name 41st parallel indicates a geographic zone aligned along
N41st of latitude. This area is longitudinally defined between the
Continental Campanian Margin (Naplean Gulf, Ischia and Procida island) and
the northwestern portion of the Sardinia Island.
From a geological point of view, the 41st parallel represents a
complicate area. Several geological structures are located along this zone:
submerged volcanic bodies such as the Etruschi,
Vercelli and Cassinis seamounts, emerged edifices connected to the
Pliocenic-Quaternary volcanism of the Central Tyrrhenian sea (Palmarola,
Zenone, Ponza, Ischia and Procida) and several
deep fault structures such as the E-W fault of Ponza.
The formation and the development of this particular zone is not clear and
is still object of discussion in literature. The structural setting of
41st
parallel zone is highlighted only by magnetic field data. By the
observation of the magnetic anomalous field it is possible to see an
alignment of several magnetic anomalies along the N41st latitude.
These anomalies take place on the main structural evidences of the area.
The bathymetric data and information don't suggest
these features. To this aim, I use the magnetic data to analyse in quantitative
way, the 41st parallel zone.
The magnetic data used for the development of the 3D magnetic model derived by
the dataset of the Aeromagnetic Anomaly Map of Italy (Caratori Tontini
et al., 2004).
The original magnetic dataset includes the total intensity field
of Italy and its surrounding seas acquired partly during the aeromagnetic
surveys performed by Agip (now Eni-Spa) between 1971 and 1980 and during
new surveys in the years 2001-2002(Eni,Exploration & Production Division -
Igmar, La Spezia). The magnetic data were recorded, in a homogeneous way,
by using a cesium-magnetometer.
By the successive reprocessing of the row magnetic data
the revised magnetic anomaly map is obtained showing a strong
informative contribution and a good agreement with the sea-level
map of Chiappini et al. (2002).
In the first chapter of this thesis I describe the geological and structural
features of the Tyrrhenian sea in general way. However, I analyse the
41st parallel zone starting from the literature data. In the second
chapter I evaluate the Bouguer gravity field of the Tyrrhenian Sea by using
two methodologies for an evaluation of the optimal Bouguer reduction density.
Using a free-air gravimetric satellite data set of the Tyrrhenian sea, I
perform a map of isostatic level of the central Tyrrhenian area. In the third
chapter I describe the properties of the Geomagnetic field and its
representation focusing my interest on the time and spatial dependencies of the
field. The successive section provides information about the row magnetic
data used for the quantitative
elaboration describing the characteristics of the anomaly field of the
studied area. In the fifth chapter, the properties of the magnetic signal is
studied by using a statistical analysis of the power spectrum
(Spector and Grant, 1970) and by the Continuous Wavelet Transform.
After these analyses, in the sixth chapter I introduce the concept of magnetic
basement and the relationship between magnetic signal and temperature.
Starting from
the regional heat-flow data (Della Vedova et al., 2001) of the Central
Tyrrhenian area the Curie Isotherm surface is modeled defining the
maximum depth of the magnetic-thermal basement. The boundaries of the
magnetic sources (top and bottom) represents the base-line for the successive
phases of quantitative analysis.
By using a 2D inversion algorithm I obtain
the map of apparent susceptibility. In the seventh chapter, I apply this
algorithm to the magnetic evidence of the 41st parallel zone and to
the Selli Line region. This procedure suggests a distribution of magnetization
that permits to connect the 41st parallel zone and the structural
elements of the Southern Tyrrhenian Sea such as the Magnaghi Basin and the
Selli Line faults system.
Starting form the results obtained by the apparent magnetization maps,
I perform a 3D inversion of magnetic data providing information about the
vertical distribution of the sources. In the eighth chapter,
that represents an important part of the thesis, I introduce the inverse
problem in the potential field analysis by a new 3D algorithm capable to
evaluate the depth to the bottom of the source.
Then, I apply this algorithm to the real magnetic dataset of the
41st and Selli Line regions. The recovered models show the shape,
location in depth and direction of development
of the magnetic generating sources suggesting the geometric relationship
between the different sources. These information are important for evaluating
the crustal setting of the study area. Finally, in the last
chapter I interpret the results of inversion process evaluating
the relationship between the 41 st
parallel and the Selli Line region. Starting from the magnetic recovered models
of these two regions I provide a chronological reconstruction of the geodynamic
evolution of the Central Tyrrhenian Sea.Università di Bologna
Unpublished
3.3. Geodinamica e struttura dell'interno della Terra
3.4. Geomagnetismo
3.5. Geologia e storia dei sistemi vulcanici
open
8
Panepinto, Stefano. "Time and space domain analysis of gravimetric data." Thesis, 2010. http://hdl.handle.net/2122/6166.
Full textAbstract:
The goal of this PhD thesis is to provide an overview on the very different aspects of modern gravimetric research. In particular, this geophysical method is applied here on the one hand as volcano monitoring tool essentially by continuous gravity observations while, on the other hand, for the construction of density-velocity 3D regional models by an integrated inversion procedure of gravimetric and seismic data.
The first section concentrates on continuous gravity observation performed at different sites of both Etna and Stromboli volcanoes. The gravity studies allow investigation of mass displacements (magma) and density variations (deep structures) under volcano edifices. Results are presented from high precision gravity measurements fully corrected using tidal and drift optimization programs and having a standard error of few μgal. Tidal analyses results of the treated data sets are also shown and discussed in the first section. Moreover, the simultaneous recording of external parameters (atmospheric pressure, temperature and humidity) is essential as their effects must be removed from the gravity records. The analyses carried out with different processing techniques on several data sets led us to point out the temperature as the responsible parameter for the annual drift present in the records of spring gravimeters. During the end of 2002 one of the gravimetric signals acquired on Mt. Etna showed, in its final residuals reaching a 5 μgal precision, a strong decrease of about 400 μgal in few hours. Correlation between this gravity decrease, on the one hand, and the other geophysical and geochemical signals – in particular the seismic and ground deformation data – as well as the observed summit activities, on the other hand, enable us to qualify the recorded gravity variation as a precursor of the 2002 eruption period. By comparison with simultaneous ground deformation data it is shown that the observed gravity changes are not in general caused by elevation changes but are due to the direct gravitational effect of subsurface movements of matter. Residual gravity changes are interpretable entirely in terms of mass changes in crater conduits and in near-surface dykes lying along know fissure system. Furthermore, the summit activity is consistent with a source at greater depth. Gravity measurements may thus not only contribute to a better understanding of some important features of geodynamics in volcanoes but may also be used directly for the monitoring and the prediction of the eruptions.
Section two addresses the unresolved question of the possible interference between tidal forces and volcanism. After the discussion of gravimetric tide results and the determination of tidal parameters, this section is completely devoted to “tidal modulation” of thermometric data acquired at sites very close to the summit active craters of Mt Etna. The intuition that these types of data may contain some geophysical signals related to the tidal stress-strain action, as an evidence of the tidal influence on volcanic processes, comes from the following boundary consideration: since the volcanic areas are characterised by high heat fluxes due to the presence of magma bodies near the surface, taking into account that convection is the major heat transfer mechanism, the tidal strain field within the volcanic edifice could affect this convective process. Some time variations of the efficiency of the convective process should produce corresponding temperature changes observable at shallow depth. The aim of the study is thus to investigate about the presence of a periodic variation due to the main lunar tidal component (M2, tidal period of 12.421 hours). This component is chosen in order to rule out the solar radiation effects. The data set at hand was thus processed with a stacking technique coupled with a wavelet analysis for a preliminary denoising. Through the proposed procedure an anomalous amplitude of the spectral component with a period equal to that of the M2 tidal wave was found. This evidence opens a scientific speculative argument about the interaction between tidal forces and volcanic processes highlighting the possibility, under some particular conditions, of dynamic triggering.
The last section deals with a seismo-gravity integrated inversion procedure for the construction of reliable 3D models of the Sicilian area and its surrounding basins. The proposed procedure allows inverting seismic and gravimetric data with a sequential technique to avoid the problematic optimization of assigning relative weights to the different types of data. The proposed procedure underlined the necessity of the different data integration although the seismic problem seemed to be a priori well constrained. Furthermore, it allowed highlighting some velocity and density features that could play a crucial rule for the reconstruction of the geodynamic evolution of the study area.Università degli studi di Palermo, I.N.G.V. sezione di Catania, International Center for Earth Tides (Royal Observatory of Belgium)
Unpublished
2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive
open
Book chapters on the topic "3D gravity model"
1
Hanif, Muhammad, and Lina Handayani. "2D and 3D Subsurface Geological Model of Baribis Fault Zone Using the Gravity Method." In Springer Proceedings in Physics, 991–97. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-0308-3_79.
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Xia, Dongrui, Lijiang Han, Yang Li, Lichuang Ma, and Junjie Yan. "Nonlinear Seismic Response Analysis of the Surrounding Rock-Tunnel System in the Mountain Areas Under SV Wave." In Advances in Transdisciplinary Engineering. IOS Press, 2021. http://dx.doi.org/10.3233/atde210185.
Full textAbstract:
The seismic responses and failure mechanisms of the tunnels embedded in the rock are quite different from those of the aboveground structures due to the dynamic interactions between tunnel and surrounding rock. In the previous studies, the tunnel models were under some extent of simplification without considering much of critical issues such as the three-dimensional (3D) characteristics, nonlinear mechanical properties or initial in-situ stress in the model, which are bound to bring the unpredictable errors in the evaluation of seismic response of tunnel-rock system. In this paper, some 3D nonlinear finite element models are established to evaluate the seismic response of surrounding rock-tunnel system in the mountain areas, considering the initial stress state of surrounding rock-tunnel system induced by gravity and excavation, General Mohr Coulomb nonlinear constitutive. Based on the proposed model, the optimal value of the longitudinal length of the model is firstly discussed to determine the value range of the model size. After that, a series of numerical parametric analyses are carried out to investigate the deformation of the surrounding rock. One important finding is that there exists a most unfavorable stress condition which makes the tunnel induce maximum seismic responses. Finally, the typical control variable method is employed to compare the results of the models established in this paper with those of the model considering or not some of significance factors, the comparison results further prove the necessity of establishing the 3D nonlinear model.
3
Glatzmaier, Gary A. "Boundaries and Geometries." In Introduction to Modeling Convection in Planets and Stars. Princeton University Press, 2013. http://dx.doi.org/10.23943/princeton/9780691141725.003.0010.
Full textAbstract:
This chapter examines how boundary and geometry affect convection. It begins with a discussion of how one can implement “absorbing” top and bottom boundaries, which reduce the large-amplitude convectively driven flows within shallow boundary layers or the reflection of internal gravity waves off these boundaries in a stable stratification. It then considers how to replace the impermeable side boundary conditions with permeable periodic side boundary conditions to allow fluid flow through these boundaries and nonzero mean flow. It also introduces “two and a half dimensional” geometry within a cartesian box geometry and describes how a fully 3D cartesian box model could be constructed. Finally, it presents a model of convection in a fully 3D spherical-shell and shows how it can be easily reduced to a 2.5D spherical-shell model. The horizontal structures are represented in terms of spherical harmonic expansions.
4
Martellini, Maurizio, and Mario Rasetti. "2+1 Dimensional Quantum Gravity as a Gaussian Fermionic System and the 3D-Ising Model." In Series on Knots and Everything, 301–41. WORLD SCIENTIFIC, 1995. http://dx.doi.org/10.1142/9789812796189_0008.
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Andresen, L., H. Jostad, K. Andersen, and A. Rahim. "Bearing capacity of offshore gravity platforms by 3D FEM." In Numerical Models in Geomechanics. Taylor & Francis, 2007. http://dx.doi.org/10.1201/noe0415440271.ch74.
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Glatzmaier, Gary A. "Rotation." In Introduction to Modeling Convection in Planets and Stars. Princeton University Press, 2013. http://dx.doi.org/10.23943/princeton/9780691141725.003.0013.
Full textAbstract:
This chapter examines the effects of rotation on convection and gravity waves. Flows in the atmospheres, oceans, and liquid cores of terrestrial planets are dominated by the Coriolis forces, as are the interiors of giant planets and stars. The sum of gravitational and centrifugal forces can go to zero at the top boundary of a rapidly rotating star or accretion disk. The time rate of change of the planetary rotation rate gives rise to Poincaré forces. The chapter first considers Coriolis, centrifugal, and Poincaré forces before explaining the modifications needed to add these effects of rotation to previous models of convection and gravity waves in 2D cartesian box and cylindrical annulus geometries, both of which now lie within a rotating equatorial plane. It also describes 2.5D rotating models and 3D spherical-shell magnetohydrodynamic dynamo models.
7
Kallio, Ulla, Thomas Klügel, Simo Marila, Swetlana Mähler, Markku Poutanen, Timo Saari, Torben Schüler, and Heli Suurmäki. "Datum Problem Handling in Local Tie Surveys at Wettzell and Metsähovi." In International Association of Geodesy Symposia. Berlin, Heidelberg: Springer Berlin Heidelberg, 2022. http://dx.doi.org/10.1007/1345_2022_155.
Full textAbstract:
AbstractThe datum problem is a fundamental issue in the network adjustment when connecting a local measurement network to an external reference frame. Datum elements in 3D networks are scale, translation, and orientation. We consider here the local tie network at geodetic core stations, where the external reference frame is the latest ITRF realization, ITRF2014, in the mean epoch of terrestrial observations.Accurate distance measurements are used for the determination of the network scale. Thus the improvement of its accuracy and the inclusion of weather measurements to account for refraction errors are essential. For rotation and translation of the network, we need external information. Angle observations are related to the coordinate system of the instrument (e.g. a tachymeter) which is usually aligned to the plumb line. Instruments have different vertical orientation at every station point and the direction of the plumb line does not coincide with the normal vector of the reference ellipsoid. Horizontally the observed set of angles are oriented in arbitrary or approximately oriented directions.External information which is needed for solving the absolute orientation are datum points, providing the link to the global coordinate system, and correction terms for the vertical orientation (deflection of the vertical), which can be derived from combined terrestrial/GNSS observations, from a gravity based geoid model, or from astronomical observations.In this article, we present the solutions/options for the datum problem in the framework of the EMPIR GeoMetre project using the example of the ITRF core stations Metsähovi and Wettzell using transformation-free approaches. The inclusion of distant targets is promising, since in small networks even a millimeter change in the coordinates of a datum point can significantly affect a local tie vector. It is shown that at both stations the determination of the deflection of the vertical using different techniques yield the same results within the measurement error.
Conference papers on the topic "3D gravity model"
1
Sonke, Mahendra K., and Rambhatla G. Sastry. "Co-seismic 3d gravity model for 2010 Chile earthquake." In International Conference on Engineering Geophysics, Al Ain, United Arab Emirates, 9-12 October 2017. Society of Exploration Geophysicists, 2017. http://dx.doi.org/10.1190/iceg2017-050.
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ZAPATA, JOSÉ A. "SPIN FOAM MODEL FOR 3D GRAVITY IN THE CONTINUUM." In Proceedings of 2002 International Conference. WORLD SCIENTIFIC, 2006. http://dx.doi.org/10.1142/9789812772732_0041.
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Lin, Wei, and Michael Zhdanov. "3d inversion of gravity and gravity gradiometry data using multinary transformation of the model parameters." In SEG Technical Program Expanded Abstracts 2016. Society of Exploration Geophysicists, 2016. http://dx.doi.org/10.1190/segam2016-13821786.1.
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Mantovani, M., A. Lovatini, K. Hayo, and L. De Luca. "3D Velocity Model Building via Simultaneous Joint Inversion of 2D Seismic and 3D Gravity Datasets." In 78th EAGE Conference and Exhibition 2016. Netherlands: EAGE Publications BV, 2016. http://dx.doi.org/10.3997/2214-4609.201601349.
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Sampietro, D., M. Capponi, K. Oikonomopoulos, D. Ktenas, E. Tartaras, and A. Stefatos. "3D model of South Crete offshore area by seismic constrained gravity inversion." In Third EAGE Eastern Mediterranean Workshop. European Association of Geoscientists & Engineers, 2021. http://dx.doi.org/10.3997/2214-4609.202137022.
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Qiu, Gengen, Hui Fang, Qing Zhong, Xiaobo Zhang, Fagen Pei, and Yongzhen Yuan. "Analysis of 2D MT inversion in approximately explaining 3D model." In International Workshop and Gravity, Electrical & Magnetic Methods and their Applications, Chenghu, China, 19-22 April 2015. Society of Exploration Geophysicists and and Chinese Geophysical Society, 2015. http://dx.doi.org/10.1190/gem2015-117.
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Sterckx, Peter, and Ian D. Walker. "Modeling and Design Optimization of Robotic Hoses for 3D Printing of Cement." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23829.
Full textAbstract:
Abstract Modeling tendon tensions for applications of tendon-actuated continuum robots under significant loading is necessary for sizing motors, tendons, and other components to ensure that the robot can safely support its mass during operation. While models exist that express tendon tensions as a function of continuum robot configuration, previously proposed models do not consider the effects of gravity on tendon tensions. In this paper, we discuss the addition of gravity to a static model previously developed for low-mass tendon-actuated continuum robots. Using the Euler-Lagrange methodology, the potential energy due to gravity is incorporated into the formulation of the equations that describe tendon tensions as a function of robot configuration. Preliminary experimental results reveal the potential of this nonzero-gravity tendon-tension model.
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Alvers, M. R., B. Lahmeyer, C. Plonka, and E. Stangeland Karlsen. "New Insights from Interactive Gravity Inversion of Complex Salt Structures - The 3D SEAM Model." In 76th EAGE Conference and Exhibition 2014. Netherlands: EAGE Publications BV, 2014. http://dx.doi.org/10.3997/2214-4609.20141553.
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Nakatsuka, Jumpei, Yuta Muraki, and Kenichi Kobori. "Center of gravity correction method for self-support of output model in 3D printer." In International Workshop on Advanced Imaging Technology (IWAIT 2022), edited by Shogo Muramatsu, Masayuki Nakajima, Jae-Gon Kim, Jing-Ming Guo, and Qian Kemao. SPIE, 2022. http://dx.doi.org/10.1117/12.2625785.
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Mahmoodi, Omid, Richard Smith, and Bill Spicer. "Using constrained inversion of gravity and magnetic field to produce a 3D litho-prediction model." In SEG Technical Program Expanded Abstracts 2016. Society of Exploration Geophysicists, 2016. http://dx.doi.org/10.1190/segam2016-13685551.1.
Full textReports on the topic "3D gravity model"
1
Goodwin, J. A., and R. J. L. Lane. The North Australian Craton 3D Gravity and Magnetic Inversion Models: A trial for first pass modelling of the entire Australian continent. Geoscience Australia, 2021. http://dx.doi.org/10.11636/record.2021.033.
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de Caritat, Patrice, Brent McInnes, and Stephen Rowins. Towards a heavy mineral map of the Australian continent: a feasibility study. Geoscience Australia, 2020. http://dx.doi.org/10.11636/record.2020.031.
Full textAbstract:
Heavy minerals (HMs) are minerals with a specific gravity greater than 2.9 g/cm3. They are commonly highly resistant to physical and chemical weathering, and therefore persist in sediments as lasting indicators of the (former) presence of the rocks they formed in. The presence/absence of certain HMs, their associations with other HMs, their concentration levels, and the geochemical patterns they form in maps or 3D models can be indicative of geological processes that contributed to their formation. Furthermore trace element and isotopic analyses of HMs have been used to vector to mineralisation or constrain timing of geological processes. The positive role of HMs in mineral exploration is well established in other countries, but comparatively little understood in Australia. Here we present the results of a pilot project that was designed to establish, test and assess a workflow to produce a HM map (or atlas of maps) and dataset for Australia. This would represent a critical step in the ability to detect anomalous HM patterns as it would establish the background HM characteristics (i.e., unrelated to mineralisation). Further the extremely rich dataset produced would be a valuable input into any future machine learning/big data-based prospectivity analysis. The pilot project consisted in selecting ten sites from the National Geochemical Survey of Australia (NGSA) and separating and analysing the HM contents from the 75-430 µm grain-size fraction of the top (0-10 cm depth) sediment samples. A workflow was established and tested based on the density separation of the HM-rich phase by combining a shake table and the use of dense liquids. The automated mineralogy quantification was performed on a TESCAN® Integrated Mineral Analyser (TIMA) that identified and mapped thousands of grains in a matter of minutes for each sample. The results indicated that: (1) the NGSA samples are appropriate for HM analysis; (2) over 40 HMs were effectively identified and quantified using TIMA automated quantitative mineralogy; (3) the resultant HMs’ mineralogy is consistent with the samples’ bulk geochemistry and regional geological setting; and (4) the HM makeup of the NGSA samples varied across the country, as shown by the mineral mounts and preliminary maps. Based on these observations, HM mapping of the continent using NGSA samples will likely result in coherent and interpretable geological patterns relating to bedrock lithology, metamorphic grade, degree of alteration and mineralisation. It could assist in geological investigations especially where outcrop is minimal, challenging to correctly attribute due to extensive weathering, or simply difficult to access. It is believed that a continental-scale HM atlas for Australia could assist in derisking mineral exploration and lead to investment, e.g., via tenement uptake, exploration, discovery and ultimately exploitation. As some HMs are hosts for technology critical elements such as rare earth elements, their systematic and internally consistent quantification and mapping could lead to resource discovery essential for a more sustainable, lower-carbon economy.