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Estudos dos parâmetros de deformação dos isótopos 24Mg, 30Mg e 32Mg; Studies of the deformation parameters of the isotopes 24mg, 30mg and 32Mg

Chisté, Vanessa
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 06/10/1999 PT
Relevância na Pesquisa
36.67%
A proposta deste trabalho é estudar as distribuições de prótons e nêutrons e suas deformações na região da "ilha de inversão". Esta região, situada entre 10 Z 14 e 19 N 21, apresentar anomalias como núcleos fortemente deformados perto do número mágico N=20. Os parâmetros de deformação de carga e de matéria dos isótopos de 24Mg, 30Mg e 32Mg foram medidos, via espalhamento inelástico do feixe secundário de Mg, através de um experimento realizado no Laboratório GANIL, Caen, França. Um feixe primário de 36S, a 77 MeV/núcleon, produziu, via fragmentação do projétil sobre um alvo de 12C, feixes secundários de 24, 30,32Mg, com 37 MeV/núcleon. O feixe secundário foi analisado nos dipolos acromáticos do espectrômetro LISE. Os parâmetros de deformação são extraídos da seção de choque de excitação do projétil de Mg para o seu primeiro estado 2+. Para medir a distribuição de carga, um alvo de 208Pb foi utilizado. Como a interação nuclear e mais forte com o 12C, este alvo foi utilizado para determinar a deformação de massa. A obtenção dos parâmetros de deformação foi feita através da comparação da são de choque experimental com a seção de choque calculada através do formalismo de canais acoplados (programa ECIS) Na comparação...

Contribuição ao estudo da deformação permanente dos solos de subleito; Contribution to study of subgrade soil permanent deformation

Ribeiro, Madalena Maria Pereira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 05/08/2013 PT
Relevância na Pesquisa
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Esta pesquisa apresenta uma contribuição ao entendimento do efeito da variação do estado de tensões e variação de umidade na compactação, na suscetibilidade à deformação permanente dos solos de subleito. Assim, um programa experimental foi desenvolvido considerando as variáveis o estado de tensões e a umidade, que são importantes na análise da evolução da deformação permanente dos solos de subleito. Para esta avaliação, foi utilizado um solo arenoso laterítico proveniente da região de Dois Córregos, estado de São Paulo, Brasil. Foram realizados ensaios de caracterização e ensaios triaxiais de cargas repetidas (módulo de resiliência e deformação permanente). Adicionalmente, foi analisado o efeito do acúmulo de deformação permanente nos valores de módulo de resiliência, que foi efetuado a partir de ensaios realizados antes e após o ensaio de deformação permanente. Além disso, de posse dos resultados de deformação permanente foi verificada a ocorrência do Shakedown. Concluiu-se que um aumento de tensões causa um aumento na deformação permanente, não sendo possível avaliar o efeito da variação de umidade na deformação permanente. Observou-se a ocorrência do Shakedown...

Deformation of elastomeric chains related to the amount and time of stretching

Yagura,Denise; Baggio,Paulo Eduardo; Carreiro,Luiz Sérgio; Takahashi,Ricardo
Fonte: Dental Press International Publicador: Dental Press International
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 EN
Relevância na Pesquisa
36.63%
OBJECTIVE: To investigate a potential relationship between degree of stretching and resulting permanent deformation of elastomeric chains (ECs) as well as whether or not stretching time has any bearing on the degree of permanent deformation. METHODS: Five-module segments of closed elastomeric chains manufactured by 3M Unitek were stretched to 10-100% of their original length in devices especially designed for this purpose, remaining submerged in artificial saliva at 37 ± 1° C and were removed sequentially after 1, 2, 3 and 4 weeks. Upon removal, each segment was measured and, once recorded the values, were statistically analyzed with the purpose of assessing the degree of permanent deformation. CONCLUSIONS: It was concluded that permanent deformation is directly proportional to the degree of stretching of the ECs assessed. The mean percentages found were 8.4% to 10% of stretching, and exceeding 20% (21.3%) when stretched by 40%, and reaching 56.6% permanent deformation when stretched 100% of their original length. Finally, the highest percentage of permanent deformation occurred during the first week and was not statistically significant after this period.

Partitioning of Localized and Diffuse Deformation in the Tibetan Plateau from Joint Inversions of Geologic and Geodetic Observations

Loveless, J. P.; Meade, Brendan J.
Fonte: Elsevier BV Publicador: Elsevier BV
Tipo: Artigo de Revista Científica
EN_US
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The spatial complexity of continental deformation in the greater Tibetan Plateau region can be defined as the extent to which relative motion of the Indian and Asian plates is partitioned between localized slip on major faults and distributed deformation. Potency rates provide a quantitative metric for determining the magnitudes of diffuse and on-fault crustal deformation, which are proportional to strain rates within crustal micro-plates and fault slip rates, respectively. We simultaneously estimate micro-plate rotation rates, interseismic elastic strain accumulation, fault slip rates on major structures, and strain rates within 24 tectonic micro-plates inferred from active fault maps in the greater Tibetan Plateau region using quasi-static block models constrained by interseismic surface velocities at 731 GPS sites and 9 Holocene–Late Quaternary geologic fault slip rates. The joint geodetic–geologic inversion indicates that geologic slip rates are kinematically consistent with differential micro-plate motions. Estimated left-lateral slip rates on the Altyn Tagh, west-central Kunlun, and Xianshuihe faults are relatively homogeneous along strike (~ 11.5, 10.5, and 11 mm/yr, respectively) while segmentation of the eastern Kunlun fault by the intersecting Elashan and Riyueshan faults results in a decreased slip rate...

Geophysical anomalies and quartz deformation of the Warburton West structure, central Australia

Glikson, Andrew Y.; Meixner, A.J.; Radke, B.; Uysal, I.T.; Saygin, E.; Vickers, J.; Mernagh, T.P.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica Formato: 18 pages
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This paper reports geophysical anomalies and intra-crystalline quartz lamellae in drill cores from the Warburton West Basin overlapping the border of South Australia and the Northern Territory. The pre-Upper Carboniferous ~450 × 300 km-large Warburton Basin, north-eastern South Australia, is marked by distinct eastern and western magnetic, gravity and low-velocity seismic tomography anomalies. Quartz grains from arenite core samples contain intra-crystalline lamellae in carbonate–quartz veins and in clastic grains, similar to those reported earlier from arenites, volcanic rocks and granites from the Warburton East Basin. Universal Stage measurements of quartz lamellae in both sub-basins define Miller–Bravais indices of {10–12} and {10–13}. In-situ quartz lamellae occur only in pre-Late Carboniferous rocks whereas lamellae-bearing clastic quartz grains occur in both pre-Late Carboniferous and post-Late Carboniferous rocks — the latter likely redeposited from the pre-Late Carboniferous basement. Quartz lamellae in clastic quartz grains are mostly curved and bent either due to tectonic deformation or to re-deformation of impact-generated planar features during crustal rebound or/and post-impact tectonic deformation. Seismic tomography low-velocity anomalies in both Warburton West Basin and Warburton East Basin suggest fracturing of the crust to depths of more than 20 km. Geophysical modelling of the Cooper Basin...

Rational definition of the flexural deformation capacity of RC column sections

Wu, Y.; Oehlers, D.; Griffith, M.
Fonte: Elsevier Sci Ltd Publicador: Elsevier Sci Ltd
Tipo: Artigo de Revista Científica
Publicado em //2004 EN
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Traditional definitions of the ultimate displacement of RC structures are usually based on strength concerns in order to maintain a substantial proportion of the initial load-carrying capacity. This kind of definition does not reflect the true deformation capacity of structures. This work reveals the qualitatively different deformation stages of RC members through analytical and numerical studies, which is then used to define ultimate displacement and displacement ductility. The study provides a clear insight into the fundamental mechanism of concrete structural deformation and reveals the following three basic parameters that affect the deformation capacity of RC sections: ultimate strain of concrete material; axial load level; and cross-sectional depth. The longitudinal reinforcement is found to reduce the deformation capacity of RC sections at axial load levels that are lower than a critical axial load level, which is near to 30% of concrete crushing load, and to increase the deformation capacity at axial load levels that are higher than the critical axial load.; http://www.elsevier.com/wps/find/journaldescription.cws_home/30415/description#description; Yu-Fei Wu, Deric J. Oehlers and Michael C. Griffith

Compressional deformation and exhumation in sedimentary basins at ‘passive’ continental margins, with implications for hydrocarbon exploration and development.

Tassone, David Ronald
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2014
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There is growing recognition that extensive phases of compressional deformation and exhumation have interrupted the post-rift subsidence histories of some economically important ‘passive’ continental margins. Understanding the distribution, magnitude, chronology and causes of exhumation and compressional deformation at these margins can reduce exploration uncertainty. The Otway and Faroe-Shetland basins along the southern Australian margin and northwest European Atlantic ‘passive’ margins, respectively, provide ideal natural laboratories to further understand syn and post-rift compressional deformation, inversion and exhumation. Post-Albian exhumation in the Otway Basin was quantified to be ~400-3600 m across the eastern and northern parts of basin using a new sonic transit time-depth trend, which represents normal compaction of volcaniclastic shales deposited within a fluvio-lacustrine environment – unlike any other such trends previously published. These estimates are consistent with those from complementary thermal, palynological and seismic datasets. Whilst the impacts of exhumation are well known for conventional hydrocarbon systems, this study is amongst the first to highlight the implications of exhumation on unconventional hydrocarbon systems...

Numerical simulation of deformation microstructures and folds in polar ice and ductile rocks

Llorens Verde, Maria Gema
Fonte: Universität Tübingen Publicador: Universität Tübingen
Tipo: Dissertation; info:eu-repo/semantics/doctoralThesis
EN
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This thesis contains 8 manuscripts for peer-reviewed journals (4 published, 2 submitted, 2 to be submitted within 4 weeks) that present studies of deformation microstructures and folds in polar ice and ductile anisotropic rocks by means of numerical simulations. It is organized in four different parts that focus: (1) Viscoplastic deformation of polycrystalline polar ice in simple and pure shear coupled with dynamic recrystallisation simulating microstructure evolution and formation of folds; (2) Folding and unfolding of single and multilayers in pure and simple shear; (3) Influence of anisotropy degree and type on rotation of rigid bodies (porphyroclasts and porphyroblasts); and (4) Analysis of the effects of dynamic recrystallisation on the rheology and microstructures of partially molten rocks. The first part (chapters 2, 3 and 4) contains three manuscripts analysing the influence of dynamic recrystallisation on deformation of pure polar ice. A full-field viscoplastic code (FFT) that fully reproduces the ice crystal’s mechanical anisotropy is coupled with dynamic recrystallisation processes to perform a series of numerical simulations in pure (chapter 2) and in simple shear (chapter 3 and 4). The results show that dynamic recrystallisation (DRX) has remarkable effects on the developed ice microstructures...

Deformation and nano-rheology of red blood cells: An AFM investigation

Bremmell, Kristin Elizabeth; Evans, Allan Mark; Prestidge, Clive Allan
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
36.67%
Interaction forces, deformation and nano-rheology of individual red blood cells in physiologically relevant solution conditions have been determined by colloid probe atomic force microscopy (AFM). On approach of the physically immobilised cell and silica glass spherical probe surfaces, deformation of the red blood cell was observed in the force curves. At low levels of deformation, spring constants were determined in the range 3–6 mN m⁻¹, whereas for higher levels of deformation, the forces increase non-linearly and on retraction, significant force curve hysteresis is observed (i.e. lower forces upon retraction). The extent of force curve hysteresis was dependent on both the drive velocity and loading force, typical of a viscoelastic system. The response of the red blood cell has been described by viscoelastic theory, where the short and long time scale elastic moduli and relaxation times are determined, i.e. the cell's nano-rheological properties elucidated. In addition to a time independent elastic modulus of 4.0 × 10³ Nm⁻² at low levels of deformation, time-dependent elastic moduli ranges are observed (3.5 × 10⁴ to 5.5 × 104 Nm⁻² at intermediate levels of deformation and 1.5 × 10⁵ to 3.0 × 10⁵ Nm⁻² at higher levels of deformation). That is...

Mechanical deformation of single-crystal ZnO

Kucheyev, S. O.; Bradby, J. E.; Williams, J. S.; Jagadish, C.; Swain, M. V.
Fonte: American Institute of Physics (AIP) Publicador: American Institute of Physics (AIP)
Tipo: Artigo de Revista Científica Formato: 3 pages
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The deformation behavior of bulk ZnO single crystals is studied by a combination of spherical nanoindentation and atomic force microscopy. Results show that ZnO exhibits plastic deformation for relatively low loads (>~4–13 mN with an ~4.2 mm radius spherical indenter). Interestingly, the elastic–plastic deformation transition threshold depends on the loading rate, with faster loading resulting, on average, in larger threshold values. Multiple discontinuities (so called ‘‘pop-in’’ events) in force–displacement curves are observed during indentation loading. No discontinuities are observed on unloading. Slip is identified as the major mode of plastic deformation in ZnO, and pop-in events are attributed to the initiation of slip. An analysis of partial load–unload data reveals values of the hardness and Young’s modulus of 5.060.1 and 111.264.7 GPa, respectively, for a plastic penetration depth of 300 nm. Physical processes determining deformation behavior of ZnO are discussed.

Structural analysis of the Paint Lake Deformation Zone, Northern Ontario /

Reilly, Brian Arthur.
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
ENG
Relevância na Pesquisa
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The Paint Lake Deformation Zone (PLDZ), located within the Superior Province of Canada, demarcates a major structural and lithological break between the Onaman-Tashota Terrane to the north and the Beardmore-Geraldton Belt to the south. The PLDZ is an east-west trending lineament, approximately 50 km in length and up to 1 km in width, comprised of an early ductile component termed the Paint Lake Shear Zone and a late brittle component known as the Paint Lake Fault. Structures associated with PLDZ development including S-, C- and C'-fabrics, stretching lineations, slickensides, C-C' intersection lineations, Z-folds and kinkbands indicate that simple shear deformation dominated during a NW-SE compressional event. Movement along the PLDZ was in a dextral sense consisting of an early differential motion with southside- down and a later strike-slip motion. Although the locus of the PLDZ may in part be lithologically controlled, mylonitization which accompanied shear zone development is not dependent on the lithological type. Conglomerate, intermediate and mafic volcanic units exhibit similar mesoscopic and microscopic structures where transected by the PLDZ. Field mapping, supported by thin section analysis, defines five strain domains increasing in intensity of deformation from shear zone boundary to centre. A change in the dominant microstructural deformation mechanism from dislocation creep to diffusion creep is observed with increasing strain during mylonitization. C'-fabric development is temporally associated with this change. A decrease in the angular relationship between C- and C'-fabrics is observed upon attaining maximum strain intensity. Strain profiling of the PLDZ demonstrates the presence of an outer primary strain gradient which exhibits a simple profile and an inner secondary strain gradient which exhibits a more complex profile. Regionally metamorphosed lithologies of lower greenschist facies outside the PLDZ were subjected to retrograde metamorphism during deformation within the PLDZ.

EVOLUTION OF INTERPHASE AND INTERGRANULAR STRAIN IN ZR-NB ALLOYS DURING DEFORMATION AT ROOM TEMPERATURE

Cai, SONG
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 8501566 bytes; application/pdf
EN; EN
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Zr-2.5Nb is currently used for pressure tubes in the CANDU (CANada Deuterium Uranium) reactor. A complete understanding of the deformation mechanism of Zr-2.5Nb is important if we are to accurately predict the in-reactor performance of pressure tubes and guarantee normal operation of the reactors. This thesis is a first step in gaining such an understanding; the deformation mechanism of ZrNb alloys at room temperature has been evaluated through studying the effect of texture and microstructure on deformation. In-situ neutron diffraction was used to monitor the evolution of the lattice strain of individual grain families along both the loading and Poisson’s directions and to track the development of interphase and intergranular strains during deformation. The following experiments were carried out with data interpreted using elasto-plastic modeling techniques: 1) Compression tests of a 100%Zr material at room temperature. 2) Tension and compression tests of hot rolled Zr-2.5Nb plate material. 3) Compression of annealed Zr-2.5Nb. 4) Cyclic loading of the hot rolled Zr-2.5Nb. 5) Compression tests of ZrNb alloys with different Nb and oxygen contents. The experimental results were interpreted using a combination of finite element (FE) and elasto-plastic self-consistent (EPSC) models. The phase properties and phase interactions well represented by the FE model...

Méthodes de génération et de validation de champs de déformation pour la recombinaison de distribution de dose à l’aide d’images 4DCT dans le cadre d’une planification de traitement de cancers pulmonaires

Labine, Alexandre
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
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36.74%
Des efforts de recherche considérables ont été déployés afin d'améliorer les résultats de traitement de cancers pulmonaires. L'étude de la déformation de l'anatomie du patient causée par la ventilation pulmonaire est au coeur du processus de planification de traitement radio-oncologique. À l'aide d'images de tomodensitométrie quadridimensionnelles (4DCT), une simulation dosimétrique peut être calculée sur les 10 ensembles d'images du 4DCT. Une méthode doit être employée afin de recombiner la dose de radiation calculée sur les 10 anatomies représentant une phase du cycle respiratoire. L'utilisation de recalage déformable d'images (DIR), une méthode de traitement d'images numériques, génère neuf champs vectoriels de déformation permettant de rapporter neuf ensembles d'images sur un ensemble de référence correspondant habituellement à la phase d'expiration profonde du cycle respiratoire. L'objectif de ce projet est d'établir une méthode de génération de champs de déformation à l'aide de la DIR conjointement à une méthode de validation de leur précision. Pour y parvenir, une méthode de segmentation automatique basée sur la déformation surfacique de surface à été créée. Cet algorithme permet d'obtenir un champ de déformation surfacique qui décrit le mouvement de l'enveloppe pulmonaire. Une interpolation volumétrique est ensuite appliquée dans le volume pulmonaire afin d'approximer la déformation interne des poumons. Finalement...

Caracterização meso e microscópica de bandas de deformação em arenitos porosos: um exemplo nas tectonossequências Paleozoica, Pré- e Sin-rifte da Bacia do Araripe, Nordeste do Brasil; Meso and microscopic characterization of deformation bands in porous sandstones: an example on the Paleozoic, Pre- and Sin-rift sequences of the Araripe Basin, Northeast of Brazil

Netto, João Marculino de Araújo; Silva, Fernando César Alves da; Sá, Emanuel Ferraz Jardim de
Fonte: Universidade de São Paulo. Instituto de Geociências Publicador: Universidade de São Paulo. Instituto de Geociências
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; Formato: application/pdf; application/octet-stream
Publicado em 01/04/2012 POR
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Bandas de deformação são estreitos volumes tabulares desenvolvidos em arenitos porosos. Apesar de produzidas em condições de deformação frágil, internamente podem apresentar gradiente de deslocamento contínuo. Quando o mecanismo de deformação dominante durante a nucleação dessas bandas é a cataclase granular, podem ser alteradas significativamente as propriedades originais de suas rochas hospedeiras, tais como porosidade e permeabilidade. Bandas de deformação, presentes nos arenitos pré- e sin-rifte da Bacia do Araripe, foram estudadas em meso e microescala com o intuito de classificá-las e de entender os mecanismos deformacionais envolvidos durante sua nucleação e desenvolvimento. Critérios geométrico-espaciais, cinemáticos e reológicos permitiram estabelecer as relações entre a gênese das bandas de deformação e a litificação dos arenitos protólitos. À luz desses dados, discutiu-se o impacto dessas estruturas no fluxo de fluido, na escala de reservatório. Além disso, o estudo das bandas de deformação auxiliou no entendimento da evolução geotectônica da bacia sedimentar estudada. Dessa maneira, o estudo das bandas de deformação pode subsidiar pesquisas sobre a evolução tectonossedimentar local e regional de bacias sedimentares.; Deformation bands are narrow tabular volumes developed in porous sandstones. Although these structures are a product of brittle deformation...

Enhancement of fluid permeability during shear deformation of a synthetic mud

Zhang, Shuqing; Cox, Stephen
Fonte: Royal Asiatic Society Publicador: Royal Asiatic Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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This study concerns the effect of stress paths on permeability and permeability anisotropy in a synthetic mud at conditions where cataclastic flow is dominant. The synthetic mud is composed of 10 wt.% montmorillonite, 40 wt.% illite, and 50 wt.% silt-sized quartz. In the experiments where the mud was first consolidated at 90 MPa effective pressure (pe) and then also sheared at 90 MPa pe, permeability decreased continuously with increasing shear displacement; subsequent shear deformation at 30 MPa and 20 MPa effective pressure resulted in permeability increases. The permeabilities parallel to and across the mud layer are similar during shear deformation at 90 MPa pe and remain so during shear deformation at lower pe. In the experiments where shear deformation commenced at 30 MPa pe after an initial consolidation at 90 MPa, permeability increased significantly with increasing displacement. Combined effects of reducing mean effective stress and shear sliding result in permeability enhancement up to two orders of magnitude. The permeability parallel to the shear direction is one order of magnitude higher than that across the shear plane. Our shear deformation experiments at high pressures confirm the importance of stress path on the evolution of fluid permeability during shear deformation. The experimental results clearly indicate that to effectively enhance permeability and to channel fluids along shear zones in wet sediments...

Structural and geochronological constraints of early Ross orogenic deformation in the Pensacola Mountains, Antarctica

Curtis, Michael L; Millar, Ian L; Storey, Bryan; Fanning, Christopher
Fonte: Association of Engineering Geologists Publicador: Association of Engineering Geologists
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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During end-Neoproterozoic to early Paleozoic time, the southern margin of Gondwana was affected by widespread subduction-related orogenesis. In East Antarctica this event is known as the Ross orogeny, whose manifestation is exposed along the 3500 km length of the Transant-arctic Mountains. In the Pensacola Mountains, the Ross orogeny is characterized by two contractional deformation events, which bracket a brief period of latest Middle Cambrian to early Late Cambrian extension and sedimentation. The oldest and most intense of these deformation events effected a succession of latest Neoproterozoic metagraywackes (Hannah Ridge Formation), producing tight to isoclinal F1 folds that possess a slaty axial-planar cleavage. Steeply plunging asymmetric F2 folds and their associated cleavage are superimposed upon the NNE-SSW D1 structural grain, forming a consistent clockwise oblique angle. Together with several shear-sense indicators, the angular relationship of D2 and D1 suggests that the F2 folds formed as a result of sinistral reactivation of D1 structures. At Serpan Peak, new meso- and microstructural observations of the Serpan Peak granite suite reveal two phases of emplacement: an early granodioritic phase emplaced prior to the regional D1 deformation event...

The role of the East Asian active margin in widespread extensional and strike-slip deformation in East Asia

Schellart, Wouter; Lister, Gordon
Fonte: Geological Society of London Publicador: Geological Society of London
Tipo: Artigo de Revista Científica
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East Asia is a region of widespread deformation, dominated by normal and strike-slip faults. Deformation has been interpreted to result from extrusion tectonics related to the India-Eurasia collision, which started in the Early Eocene. In East and SE China, however, deformation started earlier than the collision Oatest Cretaceous to Palaeocene), suggesting that extrusion tectonics is not the (only) driving mechanism for East Asia deformation. It is suggested that the East Asian active margin has influenced deformation in East Asia significantly. Along the margin, Cenozoic back-arc extension took place behind several adjoining arcs, implying eastward rollback of the subducting; slab and collapse of the overriding plate towards the retreating hinge-line. We show that extension took place along a c. 7400 km long stretch of the East Asian margin during most of the Cenozoic. Physical models are presented simulating overriding plate collapse and back-are extension. The models reproduce important aspects of the strain field in East Asia. For geometrical and rheological conditions scaled to represent East Asia, modelling shows that the active margin can be held responsible for deformation in East Asia as far west as the Baikal rift zone, located c. 3300 km from the margin.

Co-seismic deformation of the 2010 Maule, Chile earthquake: validating a least squares collocation interpolation

Gómez,D.D; Smalley,R; Langston,C.A; Piñón,D.A; Cimbaro,S.R; Bevis,M; Kendrick,E; Barón,J; Báez,J.C; Parra,H
Fonte: Geoacta Publicador: Geoacta
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2015 EN
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36.7%
Least squares collocation (LSC) has been successfully applied to develop the Velocity Model for SIRGAS (VEMOS) (Drewes and Heidbach, 2012) used to predict the velocities in the Geocentric Reference System for the Americas (Sistema de Referencia Geocéntrico para las Américas, SIRGAS) GNSS reference frame. After the 2010 (Mw 8.8) Maule, Chile earthquake, the co-seismic and ongoing post-seismic deformation changed both the coordinates and velocities of geodetic benchmarks and continuous operating GPS reference stations (CORS) within the region affected (latitude -28 to -40). This deformation made VEMOS invalid for the estimation of velocities in the reference frame. To correctly obtain coordinates in the pre-seismic frame using post-seismic coordinates, it is necessary to estimate the deformation produced by the earthquake, both co- and post-seismic. Since neither the Argentine nor the Chilean CORS GPS networks are sufficiently dense to directly determine the deformation at arbitrary locations (by using the closest station), a densification of the observations of the deformation field using LSC was recently proposed. In this paper, we used a finite element model (FEM) to simulate the co-seismic deformation of the 2010 Maule earthquake. The FEM was then used to test the LSC of the co-seismic deformation field. We found that LSC cannot be used to correctly predict the behavior of the deformation in the near field due to the complexity of the elastic response of the earth’s crust. Nevertheless...

Geologic structure of the northern margin of the Chihuahua trough: Evidence for controlled deformation during Laramide Orogeny

Carciumaru,Dana; Ortega,Roberto
Fonte: Sociedad Geológica Mexicana, A.C. Publicador: Sociedad Geológica Mexicana, A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 EN
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In this article we studied the northern part of the Laramide foreland of the Chihuahua Trough. The purpose of this work is twofold; first we studied whether the deformation involves or not the basement along crustal faults (thin- or thick- skinned deformation), and second, we studied the nature of the principal shortening directions in the Chihuahua Trough. In this region, style of deformation changes from motion on moderate to low angle thrust and reverse faults within the interior of the basin to basement involved reverse faulting on the adjacent platform. Shortening directions estimated from the geometry of folds and faults and inversion of fault slip data indicate that both basement involved structures and faults within the basin record a similar Laramide deformation style. Map scale relationships indicate that motion on high angle basement involved thrusts post dates low angle thrusting. This is consistent with the two sets of faults forming during a single progressive deformation with in - sequence - thrusting migrating out of the basin onto the platform. We found that the style of deformation in the Chihuahua trough is variable. In places such as the East Potrillo Mountains and Indio Mountains is typical of the thin- skinned style...

A rheological model of post-seismic deformation for the 2001 Kunlun, China earthquake, Mw 7.8

Zhang,Chaojun; Shi,Yaolin; Ma,Li; Lomnitz,Cinna
Fonte: Instituto de Geofísica, UNAM Publicador: Instituto de Geofísica, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2007 EN
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The Mw7.8 Kunlun earthquake of 14 November, 2001, in the northern Tibetan Plateau of China, was the largest event in the Chinese continental area in the latest 50 years. In this paper, layered visco-elastic models are calculated using the PSGRN/ PSCMP code, and the results are fitted to the observed post-seismic deformation. We show that a model of a surface anelastic layer of 10km thickness over an elastic lower crust cannot explain the observed amplitude of deformation. A relaxation model featuring 30km of elastic upper crust over 40km of a ductile lower crust will account for the main features of exponential attenuation of post-seismic deformation. Combination of the two models, however, provides an even better fit including the fact that the deformation rate was higher in the first few weeks and slower thereafter. The viscous layer in the lower crust provides good control of the post-seismic deformation, including the long term decay of deformation over a period of months. The upper anelastic layer may contribute to the observed high deformation rate in the initial few weeks after the main earthquake. The results suggest that rheological differences may exist between the materials on either side of the Kunlun fault.