Rozprawy doktorskie na temat „Deep crustal structures”
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Shi, Zhiqun. "Automatic interpretation of potential field data applied to the study of overburden thickness and deep crustal structures, South Australia". Title page, contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phs5548.pdf.
Pełny tekst źródłaGonçalves, Susana Ferreira D. S. "Geophysical characterization of the Crustal structures from Equatorial to North-East Brazilian margins". Electronic Thesis or Diss., Brest, 2023. https://theses.hal.science/tel-04619710.
Pełny tekst źródłaAdaptation and application of 3D gravity inversion with seismic constraint method to the study of the deep crustal structures of the Northwest Brazil passive margins. With a layer-stripping approach, the method has the capacity, robustness and coherency to study the geometry of the Moho discontinuity, or any other crustal layer, within the context of the passive margins environment. The obtained results have sufficient accuracy to distinguish transitions between different domains – continental domain, necking zones and oceanic domain. It is also capable to identify differences within the same domain when analyzing two parallel profiles, for example.Imaging of deep crustal structures with Reverse Time Migration method applied to two Wide-Angle Seismic data profiles, acquired by Ocean Bottom Seismometers and Land Seismic Stations. The method has capacity to image these type of structures in the two domains. The analysis of the two results is an important tool to investigate the shape and geometry of the necking zone even in profiles with asymmetric shooting. It is also shown the essential contribution of the refracted wavefield for its success.Merge of three sub-parallel Wide-Angle Seismic profiles in the Northwest area of Brazil into a unique profile of approximately 1800 km in length, providing an unique perspective on the evolution process of the opening of the South Atlantic Ocean. The merged profile showcases the similarities between the Equatorial and Central margins of the South Atlantic Ocean in spite of the different geodynamic processes and time of opening
Empinotti, Luiz Carlos Lucena. "Arcabouço crustal profundo da parte Centro-Norte da margem de Angola: modelo de afinamento e contato de crostas". Universidade do Estado do Rio de Janeiro, 2011. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=9471.
Pełny tekst źródłaThe main objectives of this study are to identify features on seismic data that allow (1) the building of a deep crustal framework and of the upper portion of the mantle, in part of the Angolan margin; (2) to compare this framework with the adjacent outcropping basement of the African continent and; (3) to try to fit these results to the published continental breakup models. In order to achieve these objectives, five deep reflection seismic lines (25 km of depth) situated in the in Kwanza and Lower Congo Basins on the passive margin of Angola were interpreted. The features identified on seismic were useful to recognize the tripartite division that caracterize the oceanic crust and in defining the Mohorovicic Discontinuity (that represents the limit between crust and mantle). The seismic interpretation associated with the data obtained from the scientific literature (that provided density values for the packages identified on seismic interpretation) allowed the establishment of a gravity modeling that was compared to the gravity data acquired during the seismic acquisition. The gravity model was useful to validate the seismic interpretation, acting as a quality control of the latter. In case of the gravity anomaly generated by the modeling not being in accordance with the measured anomaly, the seismic interpretation was revised in order to obtain a better adjustment between the modeled and the measured result. This adjustment, however, was always done honoring the reflectors that were clearly positioned on seismic. In addition, the magnetic data acquired on the field was used to help on interpretation. The crustal framework obtained by the methodology described above was compared with the passive margin evolution models found on scientific literature, showing some points in common with the models that postulate the occurrence of exhumed mantle in magma-poor passive margins. The final interpretation of these data showed the existence of a proximal domain characterized by a thick continental crust slightly thinned in contact with a distal domain marked by a hyper-extended continental crust. Oceanwards there is a region where the exhumation of the mantle took place. The passage of the proximal to the distal domain is abrupt, here termed as a Necking Zone. Oceanic crust is identified to the west of exhumed mantle. The comparison of the results obtained in this study with data from the outcropping basement on the African continent suggests a basement control on the vales of continental crust thinning attained under the basins and on the regions of exhumed mantle. Recent works done on the Angolan and Brazilian margins show features similar to the ones identified on this dissertation.
Doody, J. J. "Deep crustal seismic studies of Southwest Britain". Thesis, Bucks New University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356207.
Pełny tekst źródłaBiari, Youssef. "Structure profonde de la marge Nord-Ouest Africaine". Thesis, Brest, 2015. http://www.theses.fr/2015BRES0080/document.
Pełny tekst źródłaThe NE American margin represents one of the best studied margins in the world, it was the subject of several scientific programs. In comparison, the conjugate NW African margin remains fairly unknown, only two deep seismic cruises were acquired: the SISMAR cruise (2001) offshore the Meseta and the DAKHLA cruise (2002) offshore the Sahara. The deep structure of the Canadian margin is known due to the SMART wide-angle seismic profiles 1, 2 and 3. The first objective of the MIRROR project was to acquire combined wide-angle and deep reflection seismic data offshore a segment conjugate to the SMART-1 profile. The comparison between the homologous segments of these two margins aimed to better understand the opening mechanism of the Central Atlantic Ocean. A comparison between Sismar, Dakhla and Mirror models shows that the continental crust is thicker in the north and thins toward the south. The width of the transition zone is narrower south and Sismar profiles are located on a sedimentary basin placed on a very thinned continental crust. Comparing the Mirror profile with that of the Canadian conjugate margin (Smart 1) shows that the thickness, the structure of the continental crust and the thinning is very similar. However, zones of exhumed and serpentinized mantle were imaged along the Canadian profile that have no conjugate on the African margin. Moreover, the thickness of the oceanic crust is variable with 8 km on the African side and only 3-4 km on the Canadian margin. Several hypotheses have been proposed to explain this difference (a) an age difference between the two types of crust (b) thickening associated with the passage of the Canary hotspot (c) an asymmetric accretion or (d) an accretion at slow to ultra-slow speading centers
Hunter, Richard John. "Deep crustal structure of the central North Sea". Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46834.
Pełny tekst źródłaMarshall, A. Saskia. "High-silical peralkaline magmatism of the Greater Olkaria Volcanic Complex, Kenya Rift Valley". Thesis, Lancaster University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310585.
Pełny tekst źródłaDilles, Zoe Y. G. "Geochronologic and Petrologic Context for Deep Crustal Metamorphic Core Complex Development, East Humboldt Range, Nevada". Scholarship @ Claremont, 2016. http://scholarship.claremont.edu/scripps_theses/811.
Pełny tekst źródłaReynisson, Reynir Fjalar. "Deep structure and sub-basalt exploration of the mid-Norwegian margin with emphasis on the Møre margin". Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-11136.
Pełny tekst źródłaZhang, Sufang. "Deep structure beneath the Central-South Tibet crustal density modelling and azimuthal anisotropy variation inferred from Quasi-Love wases". Doctoral thesis, Università degli studi di Trieste, 2010. http://hdl.handle.net/10077/3621.
Pełny tekst źródłaThe area of the present study is the central part of southern Tibet. It consists of two accreted terranes, Lhasa and Himalaya terranes, which today record the deformation history that originated from the processes of collision between the Eurasia and India plates. Our study of the crust/mantle structure in terms of seismic velocity, density, anisotropy and petrologic composition are undoubtedly significant to deepen the understanding of the continent-continent collision and its dynamics. This PhD thesis can be briefly summarized into four parts that are listed in the following. 1) In order to reveal the characteristics of the crust/mantle deformation that has been generated by the Indian/Eurasia collision in the southern Tibet plateau, we study the propagation of Quasi-Love (QL) waves. Our study is based on the results from numerical modeling, which proved that QL is sensitive to lateral variation of seismic anisotropy, rather than heterogeneity and other factors. The results we obtain from processing locally observed seismograms, reveal a West-East variation of crust/mantle deformation in each terrane of the plateau. 2) A 3D density model of central-south Tibet is produced by modeling the Bouguer gravity field using all existing constraints. 3) Integrating seismic velocity and density models of the crust in the Lhasa and Himalaya terranes, we infer crustal composition models in central and southern Tibet. 4) Combining crustal density, velocity and mineralogical composition models, some important issues, such as the Indian slab subduction angle, and the relationship between crustal density and earthquake occurrences are discussed. Some results based on the gravity modeling are summarized as follows: 1) under the constraint of the geometrical structure defined by seismic data, a 3-D density model and Moho interface are proposed for central-south Tibet; 2) the lower crustal density, smaller than 3.2 g/cm3, suggests the absence of eclogite or partial eclogitization due to delamination under the central-south Tibet; 3) seismicity is strong or weak in correspondence of the most negative Bouguer gravity anomaly, so there is not a relationship between them; 4) the composition of the lower crust, determined after the temperature-pressure calibration of seismic P wave velocity, might be one or a mixture of: 1. amphibolite and greenschist facies basalt beneath the Qiangtang terrane; 2. gabbro-norite-troctolite and mafic granulite beneath the Lhasa terrane. When using the data set published by Rudnick & Fountain (1995), the composition of the middle crust turns out to be granulite facies and might be pelitic gneisses. Granulite facies used to be interpreted as residues of partial melting, which coincides with the previous study by Yang et al. (2002) on partial melting in the middle crust. Amphibolite facies are thought to be produced after delamination, when underplating works in the rebound of the lower crust and lithospheric mantle. From the seismology study, I have made the following conclusions: 1) through numerical simulation of surface wave propagation in heterogeneous media, we find that amplitude and polarization of surface wave only change a little when considering heterogeneity and QL waves, generated by surface wave scattering, are caused by lateral variation of anisotropy. 2) QL waves have been identified from the seismograms of selected paths recorded by the Tibetan station CAD, and are utilized to determine the variation of the uppermost mantle anisotropy of the Tibetan plateau. The location of the azimuthal anisotropy gradient is estimated from the group velocities of Rayleigh wave, Love wave and QL wave. We find that a predominant south-north lateral variation of azimuthal anisotropy is located in correspondence of the Tanggula mountain, and a predominant east-west lateral variation of azimuthal anisotropy is found to the north of the Gandese mountain (near 85°E longitude and 30°N latitude) and near the Jinsha river fault (near 85°E longitude and 35°N latitude).
XXI Ciclo
1981
Hitz, Luzi. "Crustal structure at the transition between central and eastern Alps : processing, 3D modeling and interpretation of a network of deep seismic profiles /". Bern : [s.n.], 1994. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
Pełny tekst źródłaFraser, James. "The structural and metamorphic evolution of the deep crust in the Hunza Karakoram, Pakistan". Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393754.
Pełny tekst źródłaPerosi, Fábio André. ""Estrutura crustal do setor central da província Tocantins utilizando ondas p, s e fases refletidas com dados de refração sísmica profunda"". Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/14/14132/tde-18072006-124456/.
Pełny tekst źródłaThis research is based on an execution of two lines of deep seismic refraction of 300 km of extension (L1-Porangatu and L2-Cavalcante), crossing over central sector of Tocantins Province from west to east by using, in each line, 120 digital seismographs and explosions with controlled time and explosive charges between 500 and 1,000 kg in each 50 km; GPS receivers were employed in order to control the time and geographical coordinates from recording and shot points. This kind of experiment under these explained conditions is pioneer in Brazil. Initially experiment data, which have been considered of good quality, allowed the elaboration of 1D models, using TTInvers program. Successive models were related to represent layers with similar characteristics in a preliminary model aiming of modelling in 2D, accomplished with MacRay program. Obtained 2D models represent the final result of seismic velocity distribution from crust beneath L1 and L2 lines. Results show crust under central section of Tocantins Province with thickness varying from 36 to 43 km, and whose parameters are correlated to main geological structures existents in surface. VP as well as VP/VS ratio mean values vary about 6.5 km/s and 1.74, respectively, with the exception of fold-and-thrust belt, whose values are 6.3 km/s and 1.73. Those values reach 6.8 km/s and 1.74 beneath São Francisco craton. There are indicia of double subduction occurred in the eastern portion of Tocantins Province with São Francisco Cráton subducting to west (in | 760 Ma), as well as in the western portion, with Amazon Cráton subducting to east (in | 620 Ma). The gravimetric model, obtained in this work in terms of seismic model, adequately adjusts with observed gravimetric data by using theoretical densities slightly modified, within limits allowed by the function employed to calculating the densities based on VP values achieved from this work. Adopted mantle densities to modelling took in consideration Paleoproterozoic age, beneath São Francisco Cráton, less dense (3.31 g/cm3), and with higher VP (8.26 km/s), as well as Neoproterozoic one, beneath Tocantins Province, denser (3.34 g/cm3), and with lower VP (8.07 km/s).
Shibutani, Takuo. "Multi-trace receiver function inversion of nearby deep earthquake waveforms to estimate S wave volocity structure of the crust and uppermost mantle". 京都大学 (Kyoto University), 1993. http://hdl.handle.net/2433/86445.
Pełny tekst źródłaTsai, Ching-Hui, i 蔡慶輝. "Study of crustal structures and deep-sea sediment waves in the northern South China Sea". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/90322780924963176476.
Pełny tekst źródła國立中央大學
地球物理研究所
95
There are two main topics presented in this thesis. First is to use reflection seismic data and gravity modeling to study the crustal structures in the northern continental margin of the South China Sea (SCS). Another topic is to use high resolution seismic and chirp sonar data to study deep-sea sedimemt waves in the north and south sides of downstream of the Formosa Canyon. Additionally, we present the foundamatal procedures of data collecting and processing of the multi-beam bathymetry data and show a preliminary result of new bathymetry map off southwest Taiwan. We can distinguish the crustal strutures in the northern margin of the South China Sea into three partions: the continental crust (CC), the thinned continental crust (TCC) and oceanic crust (OC). The TCC zone displays a steeper slope and Moho depth becomes shallow oceanward from about 24 km to about 14 km deep. The corresponding crustal thickness is from 20 km thick to about 10 km thick and is located in a relatively low free-air gravity zone. According to the seicmic data, crustal modeling results and magnetic anomaly curves, the OC could be existed further northward and the continent-ocean boundary is along the base of continental slope. Because the volcanism happened after sea floor spreading, there are many intrusive or extrusive igneous bodies around the Dongsha Island. Thus, we can find a possible underplating in this area. Volcanism in this area also causes the abnormal thick oceanic crust in the southeast of the Dongsha Island. In the northern SCS, the deep-sea sediment wave fields are located in two zones, one is between downstream of the Formosa Canyon and Penghu Canyon, the other is between downstream of the Formosa Canon and LRTPB (Luzon-Ryukyu Transform Plate Boundary). The distribution of these deep-sea sediment waves are found below 3000 m deep and the wave front is rather parallel to the bathymetric contour lines. Base on high resolution sesmic data, we suggest that these sediment waves are caused by turbidity currents. The sediment waves have shown asymmetrical internal structures which may induced by high gravity flow activity. Most of these sediment waves are less than 85 m high, and most of wavelengthes are less than 6 km long. Most of slopes are less 0.8 degree. We suggest that the Formosa Canyon and Penghu Canyon are two major sediment transportation channels. The turbidity flows downward and may overflow directly from the turning points of the two canyons. The sediment deposits in the stoss side and erodes in the lee side. It proceedes downslope continuously because of gravity effect. Due to the bathymetric offset of the LRTPB, the turbidity current can not overflow southwards from this tectonic structure, which makes LRTPB a natural sediment wave dam.
Liao, Yen-Che, i 廖彥喆. "Analyzing Deep Crustal Structure Beneath Taiwan Region By Receiver Function". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/99840397731100659623.
Pełny tekst źródłaLang, Zhongmin. "Geophysical study of deep-crustal structure: Mid-Atlantic passive continental margin". Thesis, 1997. http://hdl.handle.net/1911/17396.
Pełny tekst źródłaGoleby, Bruce Ronald. "The crustal structure of the Arunta Block, Central Australia : results from deep seismic reflection profiling". Phd thesis, 1990. http://hdl.handle.net/1885/140376.
Pełny tekst źródłaAustin, James R. "The Cloncurry Lineament: a long-lived deep crustal structure that acted as a metasomatic pathway during ca 1530-1500 Cu-Au mineralisation, Mount Isa Inlier, Australia". Thesis, 2007. https://researchonline.jcu.edu.au/18948/2/18948-austin-2007-thesis-chapters.pdf.
Pełny tekst źródłaMahan, Kevin H. "Exhumation of exposed deep continental crust, western Canadian Shield: Integrating structural analysis, petrology, and in situ geochronology". 2005. https://scholarworks.umass.edu/dissertations/AAI3193921.
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