The recognition of fault-perturbed stress fields is an important tool in areas of mineral or hydrocarbon exploration. The Bowie underground coal mines of western Colorado expose a reverse-reactivated growth fault that perturbed the stress field during cleat (fracture) formation, rotating cleat orientations up to 500 m on both sides of the fault. Two unusual fracture types are found only in coal adjacent to the fault: (1) concentric cleats, highly curved fractures that form blocks resembling balls or eggs and (2) horsetail cleats, striated surfaces that superficially resemble shattercones and result from shear failure in coal. Numerical models created with the boundary element program Poly3D were used to estimate the magnitudes and orientations of the paleostress axes during cleat formation, taking into account the depth of burial, 3-D fault orientation, elastic rock parameters, and far-field stress states. When the elastic rock parameters and modeled orientations of the stress axes are held constant, the relative stress ratio, R = (σ_1 — σ_2)/(σ_2 — σ_3), uniquely determines the orientations of fractures forming in the fault-perturbed stress field. Comparison of the models with systematic observations on both sides of the fault allows the selection of a best-fit model. If the depth of overburden during fracture formation is known, this technique can be used to estimate the magnitude of σ_1 in fault-perturbed areas. The rotated face cleats and unusual, fault-related cleat types provide unequivocal evidence of a fault when (1) the fault predates cleat formation and (2) the far-field horizontal stress during cleat formation is oblique to fault strike. In addition, the varying spatial association of these fault-perturbed cleat styles with the fault may provide a qualitative estimate of fault location while mining. Pre-existing faults also strongly control reactivation-related folding, which at formed several low-amplitude folds, including a footwall fold. Igneous sills in three Bowie coal seams show strong preference for fault zones. The recognition of similar fracture trends in other mining or exploration areas is a valuable tool that may significantly reduce economic or human cost by helping to mitigate fault-related hazards and highlighting potentially productive zones in faulted reservoirs.

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No description available.

In nature, rock masses are not static, but constantly changing with erosion, metamorphosis, tectonics and more. Rocks that bend and buckle can be seen almost as nature's origami, being folded into new shapes and structures. During shortening of a sequence of sedimentary layers, they fold and/or thrust to accommodate the convergence. Folds initiate as kinks which may evolve into thrusts. These folds and thrusts form a wedge which grows in height and length with continued convergence. This study examines the sequence of formation of kinking in fold and thrust belts, specifically the development of forekinks from thrusting and the evolution of the wedge. This was done through geometric analysis of images taken of an analogue sandbox model, run in 2011, which consisted of horizontal layers shortened from one end to 25% bulk convergence above a rigid basement. In nature, such wedges are found as accretionary prisms in convergence zones and as fold and thrust belts on either side of an orogen. By simulating the creation of these wedges and kinks with controlled parameters, it is possible to gain an understanding of the mechanical processes involved in their creation, which allows for a better understanding of these processes in nature. This study is mainly based on measurements of separation created by kinking, dip of the kinks at different levels, and the dimensions of the wedge, in addition to other geometric features. The results showed clear trends for the evolution of these geometric features with progressive model shortening. Results show that, forekinks become inactive when a new kink develops in its foreland. The amount of separation within a kink is dependent on how soon a new kink is developed in front of it and the throw (vertical component) is generally larger than the heave (horizontal component). Dip of a forekink steepens as the forekink cumulatively rotates backwards by the creation of new forekinks in front of it. Evolution of the forekinks has a direct impact on wedge development. Wedge length is larger than height and as the shortened layers are compacted, the dimensions of the wedge increase at different rates. Generally the results of this study are in agreement with previous research conducted within the subject. If rock folding is nature’s origami, then the study of these processes can allow us to understand how fold and thrust belts develop, just as studying how a piece of paper folds, can show us how a napkin can transform into a swan. / I naturen är bergmassor inte statiska utan förändras ständigt av erosion, metamorfos, tektonik med mera. Berg som böjs och bänds kan nästan ses som naturens origami; veckandes till nya former och strukturer. Under förkortning av en sekvens sedimentära lager viker de sig och/eller förkastas för att tillgodose konvergensen. Ett veck i ett lager kan så småningom utvecklas till en förkastning. Dessa veck och förkastningar bildar en kil som växer både på höjden och längden med fortsatt konvergens. Denna studie undersöker veckbildning i bergskedjor, specifikt utvecklingen av framåtvända veck och kilens utveckling. Detta gjordes genom geometrisk analys av bilder tagna av ett försök utfört i en analog Sandbox-modell (gjort 2011) som bestod av horisontella lager förkortade från ena änden till 25% bulk-förkortning ovanför en fast bas. Kilar såsom de som ses i modellen hittas i naturen som accretionära prismor i konvergenszoner och på vardera sida om bergskedjor. Genom att simulera skapandet av dessa kilar och veck i en kontrollerad miljö är det möjligt att skapa sig en förståelse för de mekaniska processer som är involverade i dess skapande, vilket möjliggör en bättre förståelse av dessa processer i naturen. Denna studie är huvudsakligen baserad på mätning av separation skapad av veckning, veckens stupning vid olika djup och kilens dimensioner, tillsammans med andra geometriska egenskaper. Resultaten visade tydliga trender för utvecklingen av dessa geometriska egenskaper i samband med att modellen förkortades. Resultaten visar att framåtvända veck blir inaktiva när ett nytt veck utvecklas framför den. Mängden separation inom ett veck beror på hur snart det nya vecket utvecklas framför den och kast (vertikal komponent) är i allmänhet större än hiv (horisontell komponent). Stupning av ett veck blir brantare när vecket kumulativt roterar bakåt genom att det skapas nya veck framför den. Utvecklingen av vecken har en direkt inverkan på kilens utveckling. Kilen är längre än den är hög och då de förkortade lagren komprimeras växer kilens dimensioner i olika takt. Överlag överensstämmer resultaten av denna studie med tidigare forskning inom ämnet. Om veckandet av bergmassor är naturens origami, kan studerandet av dessa processer möjliggöra för oss att förstå hur bergskedjor utvecklas, precis som att studerandet av hur ett papper viker sig, kan visa oss hur en servett kan förvandlas till en svan.

At present, the most accurate approach to predicting protein structure, comparative modelling, builds a model of a target sequence using known protein structures as templates. Comparative modelling becomes markedly less accurate in the ‘twilight zone’, where the target protein shares little sequence identity with all known templates. There are two main causes of this inaccuracy: first, it becomes difficult to identify good structural templates; second, it becomes difficult to determine which amino acids in the template are structurally equivalent to those in the target. These are problems of fold recognition and target-template alignment respectively. In this thesis, new approaches are developed to address both these problems. The alignment problem is investigated in the special case of membrane proteins. These are key modelling targets as they resist structure determination and are pharmaceutically important. The approach taken here is to use ‘environment specific substitution tables’ (ESSTs)– that is, to alter the alignment scoring system for each local environment of the template structure. We show how ESSTs can be made for membrane proteins, tested for robustness of construction, and used to infer the most important evolutionary pressures acting on protein structure. The incorporation of ESSTs into a multiple sequence alignment method leads to more accurate alignments of membrane proteins, and so to more accurate models. Recently, algorithms have been developed that predict contacts in protein structures from a multiple sequence alignment of homologous sequences. We explore the potential of these predictions for fold recognition by developing an algorithm that makes no use of amino acid identity, and so should be agnostic to the existence of a ‘twilight zone’. We show that whilst this is not the case, our method is complementary to state-of-the-art approaches.

Protein evolution is a complex and diverse process, yielding an incredible assortment of biological functions and pathways occurring in the cells of living organisms. The way in which a protein's structure is constrained by its functional role and its notable conservation across even distant evolutionary relationships highlight structure as an important unit when considering the evolutionary dynamics of proteins. This thesis attempts to place the structural landscape of the protein universe within an evolutionary framework. We investigate potential evolutionary histories of protein superfamilies by introducing an age, which estimates when the ancestor of that superfamily first evolved. The range of ages of known protein superfamilies goes right back to those which evolved before the diversification of life into three major superkingdoms. The structures of these proteins are varied but those which have evolved more recently tend to be shorter and have a less elaborate globular packing. Protein structures sit within a complex global landscape of three-dimensional folds and we attempt to model the dynamics of this space using networks of folds. These networks consist of a structurally diverse core of folds with older ages, and neighbouring folds tend to be of similar ages. Moreover, there are a few pivotal folds which appear repeatedly as central in the landscapes, connecting together otherwise disparate portions of the space. Sequence profiles which capture patterns of conservation and variation amongst naturally occurring proteins within a superfamily can be compared to identify distant evolutionary relationships. The power of these profiles to detect such relationships is improved by seeding them with structural alignments. A landscape of evolutionary links crossing between different protein folds is presented.

La présente étude porte sur les caractéristiques structurales de la zone de cisaillement de Kandi dans la région Savalou-Dassa au Centre-Bénin et ses relations avec le magmatisme spatialement associé. Elle vise à comprendre l’évolution tardi- à post-collision de la chaîne panafricaine des Dahoméyides. Les études structurales, pétrologiques et géochronologiques indiquent que la zone de cisaillement de Kandi au Centre-Bénin correspond à un décrochement ductile dextre, large d’au moins 50 Km, et dans laquelle l’évolution de la déformation jusqu’à plus basse température a entraîné l’apparition des bandes de tectonites d’épaisseur kilométrique. Le décrochement ductile de Kandi a fonctionné dans la chaîne des Dahoméyides à partir de c. 606 Ma et il a affecté des granulites d’âge paléoprotérozoïque et des gneiss, migmatites et granitoïdes néoprotérozoïques. Les magmatites spatialement associés à la zone de cisaillement de Kandi sont anté- et syn-décrochements ductiles. Le magmatisme anté-décrochement ductile est sub-alcalin et comporte une composante crustale et une composante mantellique appauvrie. Le magmatisme sub-alcalin s’est poursuivi au cours du décrochement ductile et cette période se caractérise par un cogénétisme plutonisme-volcanisme. De même, on observe une transition de magmas sub-alcalins-alcalins, qui traduit un changement de sources mantelliques-manteau appauvri manteau enrichi. Nous montrons également que le bassin volcano-sédimentaire de Idaho-Mahou est ouvert par le jeu de décrochements. Les volcanites du bassin, présentant des analogies de composition chimique et de chronologie de mise en place avec le pluton syn-cisaillement de Fita, indiquent que ce bassin est syn-orogénique, intramontagneux. La présence de magmas d’origine mantellique remontant dans la zone de cisaillement implique l’ampleur lithosphérique de la zone de cisaillement de Kandi. La synthèse des données indique que le fonctionnement du décrochement ductile de Kandi est contemporain de l’édifice de nappes et chevauchements dans les unités externes des Dahoméyides et démontre ainsi une partition de la déformation à l’échelle de la chaîne pendant la période post-collision. Elle indique également que le fonctionnement du décrochement ductile de Kandi à l’Ouest de la chaîne des Dahoméyides est synchrone de la période d’activité des zones de cisaillement à l’Est de la chaîne et du Hoggar et du Brésil / The present study focuses on the structural characteristics of the Kandi shear zone (KSZ) and the time and space relationships between deformation and magmatic events in the central region of Bénin. This tectonic structure is a segment of a lithospheric-scale shear zone that extends from the Hoggar massif (Algeria) to the Atlantic Coast in Bénin and continues down to western Brazil. The present work aims at better understanding the late to post-collision geodynamic evolution of the pan African Dahomeyide fold beltIn summary, this study reveals that the Kandi shear zone in the Central-Bénin is a large (more than 50 km width) dextral transcurrent shear zone, where the latest increments of deformation occur as more localized (kilometric-scale width) shear bands at low temperature. The KSZ activity started at c. 610 Ma and affected the rock basement, including Paleoproterozoic granulites and Neoproterozoic gneisses, migmatites and granitoids. The granitoids intrusions that are spatially associated to the KSZ display ante- to syn-shearing structural features. The earliest intrusion, ante-tectonic Dassa has sub-alkaline affinity deriving from crustal and depleted mantle magmas. This sub-alkaline series carry on during the transcurrent shearing with the Gobada, Tré, Tchetti intrusions. The latest magmatic event of Fita intrusion suggests the transition from sub-alkaline to alkaline magmas, probably reflecting mantle source evolution, from depleted to enriched mantle. We also showed that the Idaho-Mahou volcano-sedimentary basin opened during the transcurrent shearing and the volcanic mafic and felsic rocks are probably related to the successive sub-alkaline to alkaline intrusions. The occurrence of mantle-derived magmas in the shear zone confirms the lithospheric scale of the Kandi shear zone. According to the available radiometric data from the Dahomeyides fold belt, the Kandi shear zone activity seems to contemporaneous with the nappes stacking and thrusting stages in the external orogenic zone (Atacora and western Benin plain) orogen-scale. It also indicates that the KSZ was coeval with the major shear zones from the easternmost region of the Dahomeyides fold belt (NE Nigeria), of the Hoggar and Braziliano belts.

Cette thèse traite de l’enregistrement de la déformation, à différentes échelles de temps et d’espace dans la chaîne plissée de Malargüe et le bloc de San Rafael, situés dans la partie septentrionale du bassin de Neuquén en Argentine. La première partie du travail comprend une analyse de la déformation finie (chaîne de Malargüe) et de la déformation active (bloc de San Rafael) à l’échelle macroscopique. De manière générale, les coupes structurales régionales proposées mettent clairement en évidence le rôle l’héritage structural lié aux structures générées lors de l’ouverture du bassin au Jurassique. Nous montrons également que les mécanismes de soulèvement actuels du bloc de San Rafael à l’est reprennent les modalités de la déformation d’âge Miocène dans la chaîne. Contrairement au mode de structuration des prismes critiques classiques caractérisés par la localisation de la déformation le long d’un niveau de décollement, la structuration de la chaîne est ici issue d’une déformation distribuée plus largement dans la lithosphère. A l’échelle de l’endommagement mesoscopique, la fracturation régionale nous a permis d’enregistrer les différents champs de contraintes régionaux liés aux phases de raccourcissement depuis le domaine pré-plissement jusqu’à la phase syn-plissement. Ces différentes phases sont en accord avec la cinématique de la convergence de la plaque Nazca depuis le Crétacé supérieur. A l’échelle microscopique, l’analyse des propriétés de susceptibilité magnétique des roches met en évidence, d’une part, une compartimentalisation de la déformation à l’échelle de la matrice liée à l’héritage structural extensif. D’autre part, la distribution spatiale de cet endommagement ne démontre pas l’existence de gradient clair des fabriques magnétiques depuis l’avant-pays vers les zones internes ce qui confirme le caractère atypique du système Andin à la latitude de 35°S. Ce dernier étant principalement contrôlé par une déformation distribuée, liée à l’héritage structural et singulièrement différente de celle attendu dans le cadre de la théorie du prisme critique. / This PhD project deals with multiscale record of the tectonic signal in the Malargüe fold-and-thrust-belt (MFTB) located in the northern part of the Neuquén basin (Argentina). The first results presented rely on the study of the macroscopic finite strain in the fold-belt and the characterization of the active deformation of the San Rafael Block uplift. The cross-sections we produce show that structural inheritance related to the Jurassic extension is the main parameter controlling the belt structure. In addition we proposed that the building mechanisms that controlled the MFTB evolution by Miocene times are the same than those triggering the present day San Rafael block uplift. The second part of this work is dedicated to mesoscopic strain pattern analysis recorded by fracture networks. Throughout the MFTB, we are able to describe the occurrence of four main fractures sets emplaced in several stress regime that are linked (1) to the inheritance and (2) to the well-known compression phases from pre-folding to syn-folding settings. Finally the third part of this work describes the microscopic damage recorded by the anisotropy of magnetic susceptibility method. We mainly evidence that there is no clear gradient of magnetic fabrics from foreland to hinterland and that deformation is compartmentalized by structural inheritance. This atypical pattern of magnetic fabrics succession reveals that the matrix damage is governed by the same strain distribution as those observed at macroscopic scale thus providing a supplementary argument to consider the Andean system at these latitudes as singularly different from a classical Coulomb wedge.

[pt] Seja (Es)t o espaço de germes na origem de funções suaves entre os espaços euclidianos de dimensões e t. Nesta dissertação, apresentamos a parte da Teoria de Mather que descreve hipóteses suficientes para k-determinação em (Es)t sob duas ações diferentes, induzindo as chamadas R- e K-equivalências. Um germe é k-determinado se é equivalente a qualquer perturbação que deixa invariante seu k-jato, os termos de ordem até k de sua expansão de Taylor na origem. A R-equivalência consiste em compor germes com germes de difeomorfismos µa direita. A K- equivalência é mais difícil de descrever. / [en] Let (Es)t be the space of smooth map-germs at the origin between Euclidian spaces of dimensions s and t. In this dissertation, we present a section of Mather theory describing su±cient conditions for k- determinacy of this map-germs under two different actions, inducing the so called R- e K- equivalences. A map-germ is k-determined if it is equivalent to any perturbation that leaves invariant its k-jet, i.e., the terms up to order k of its Taylor expansion at the origin. The R-equivalence consists of compositions with germs of diffeomorphisms to the right. The K- equivalence is harder to describe.

BEGINNING MIDDLE AND is a project that takes a textile approach to explore repeated pattern and the ongoing. This paper, being a part of this project, is describing and discussing the potentiality of using notions such as softness, folds and ongoingness to widen the views on what a craft practice can be and do. This raises questions about the relevancy of ideas such as finished and the one piece, in a craft context. Based on the properties of a resist dyeing technique, the paper puts the fold in relation to pattern and modularity. It wants to discuss what a fold is and how ideas of folding and unfolding could engage with process based artistic work. Constantly shifting between perspectives and looking for overlaps, the text then touches upon paradoxes and dilemmas found when unfolding the systems and the unruliness that together form the work. Looking at acts of unfinishing, it tries to understand the fascination and the fear that is triggered by incompleteness. The beginning is a wish to enhance the complexity of my craft practice, and to expand the understanding of it. But realizing the difficulties in doing so, the reasoning eventually ends up at the challenging task to break free from your own habits, trying to find a new beginning.