Principles of Rock Deformation and Tectonics最新文献

Horizontal/vertical displacements and their rates 水平/垂直位移及其速率

Principles of Rock Deformation and Tectonics Pub Date : 2021-08-31 DOI: 10.1093/oso/9780192843876.003.0009

J. Bouchez, A. Nicolas

{"title":"Horizontal/vertical displacements and their rates","authors":"J. Bouchez, A. Nicolas","doi":"10.1093/oso/9780192843876.003.0009","DOIUrl":"https://doi.org/10.1093/oso/9780192843876.003.0009","url":null,"abstract":"This chapter widens our scope towards translation and rotation. These displacements are critical in tectonic studies along with distortion, which has so far been the main subject of this book. Note that a translation needs a fixed reference to be defined. Consider, for example, the glide of the lithosphere over the asthenosphere with respect to the mid-Atlantic ridge. On a spherical surface, a translation is also a rotation, where the horizontal displacement of a plate is governed by a rotation axis (or pole) and an angular velocity. Vertical displacements of the Earth’s surface are one order of magnitude less (on the order of mm per year) than horizontal displacements. Lots of studies, performed in the frame of a discipline called neotectonics, attempt to determine uplift rates through different techniques, such as fission track and radioactive decay. They will be briefly presented in this chapter. The main reference for vertical displacements is the sea level, which itself is mobile through time. This mobility is obviously sensitive when processes such as erosion or post-glacial rebound are considered, but much less significant when exhumation of deep-seated rocks may reach kilometres during an orogeny.","PeriodicalId":146168,"journal":{"name":"Principles of Rock Deformation and Tectonics","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131559108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Ductile deformation and microstructures 韧性变形与显微组织

Principles of Rock Deformation and Tectonics Pub Date : 2021-08-31 DOI: 10.1093/oso/9780192843876.003.0004

J. Bouchez, A. Nicolas

{"title":"Ductile deformation and microstructures","authors":"J. Bouchez, A. Nicolas","doi":"10.1093/oso/9780192843876.003.0004","DOIUrl":"https://doi.org/10.1093/oso/9780192843876.003.0004","url":null,"abstract":"In contrast to the elastic deformation, which is reversible, usually neglected by field geologists but important for geophysicists working in seismology, ductile deformation is irreversible. This chapter is restricted to solid materials. Materials containing a melt fraction will be examined in Chapter 7. In the geological literature, ‘ductile’ is often used as a synonym for ‘plastic’. The latter is rather used, and will be used to specify deformation mechanisms that dominantly involve the action of dislocations. In contrast to brittle deformation, which by essence is discontinuous and highly localized (see Chapter 3), ductile deformation is generally continuous and affects large volumes of rock. However, ductile deformation may be concentrated into restricted rock volumes (or domains). Such localization is common in shear zones and/or when superplastic deformation mechanism is involved. Plastic deformation mechanisms naturally depend on temperature, magnitude of the applied stress, mineral nature and grain-size of the rocks. In upper parts of the crust, fluids are able to carry chemical elements over large distances and influence the deformation mechanisms. Micrographs of several microstructural types as well as deformation maps for olivine and calcite are given at the end of this chapter.","PeriodicalId":146168,"journal":{"name":"Principles of Rock Deformation and Tectonics","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131755926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Brittle deformation 脆性变形

Principles of Rock Deformation and Tectonics Pub Date : 2021-08-31 DOI: 10.1093/oso/9780192843876.003.0002

J. Bouchez, A. Nicolas

{"title":"Brittle deformation","authors":"J. Bouchez, A. Nicolas","doi":"10.1093/oso/9780192843876.003.0002","DOIUrl":"https://doi.org/10.1093/oso/9780192843876.003.0002","url":null,"abstract":"By nature, brittle deformation is discontinuous. It is often studied through mechanical tests, both in laboratories and outdoors, in mines and quarries. Brittle deformation also concerns civil engineering (road maintenance, strength of retaining structures such as bridges, dams, galleries etc.) and is well integrated with investigations in rock mechanics. Hydraulic fracturing is extensively used in the geothermal sector, for oil or gas production enhancement, or recovery of shale gas. Along with in-situ stress measurements, it has expanded the interest of geologists within the domain of rock mechanics. A solid knowledge of the mechanisms governing rock failure is necessary to understand the processes operating at the origin of earthquakes and volcanic eruptions, as well as the genesis of ore vein deposits. Beyond the elastic threshold of mechanical tests, rock failure takes place after development of a certain amount of non-elastic deformation. The fact that a progressive transition exists between ductile and brittle deformation suggests that these two behaviours are not mutually exclusive. Indeed, the study of the brittle-ductile transition paves the way to new concepts that enrich our understanding of the mechanisms of failure, in turn allowing practical applications. In this chapter, a presentation of the relationships between fracture orientation and principal stress directions will be followed by an examination of the macroscopic and microscopic aspects of brittle deformation.","PeriodicalId":146168,"journal":{"name":"Principles of Rock Deformation and Tectonics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128808425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Deformation/strain and stress 变形/应变和应力

Principles of Rock Deformation and Tectonics Pub Date : 2021-08-31 DOI: 10.1093/oso/9780192843876.003.0001

J. Bouchez, A. Nicolas

引用次数: 0

Magmatic fabrics, structures and microstructures 岩浆构造、构造和微观构造

Principles of Rock Deformation and Tectonics Pub Date : 2021-08-31 DOI: 10.1093/oso/9780192843876.003.0007

J. Bouchez, A. Nicolas

{"title":"Magmatic fabrics, structures and microstructures","authors":"J. Bouchez, A. Nicolas","doi":"10.1093/oso/9780192843876.003.0007","DOIUrl":"https://doi.org/10.1093/oso/9780192843876.003.0007","url":null,"abstract":"A magma is a two-phase material made of crystals immersed in a silicate melt, which displays a high viscosity contrast between the liquid and the solid fractions. A specific rheological behaviour is therefore expected from such a material, particularly as a function of the volume ratio between phases. Emplacement of magma to shallower levels of earth’s crust results in crystallization. As a consequence, crystal percentage increases and volume ratio between phases changes. Different structures at both the mesoscopic (field) and microscopic scales develop, which are characteristic of a particular crystal fraction. These aspects, and how shape preferred orientations (shape fabrics) develop in magmas, are discussed in this chapter. Rheological aspects of magma systems are presented, illustrated by significant microstructural features observed in granites. Our focus will then concern the construction mode of magmatic fabrics. Examples will demonstrate that, with the help of microstructures and sometimes of near-field gravity data distribution, emplacement modes of plutons are rather simple to analyse. Finally, mafic rocks will be considered at the end of chapter through case studies concerning, principally, the Skaergaard complex and gabbros from the oceanic crust.","PeriodicalId":146168,"journal":{"name":"Principles of Rock Deformation and Tectonics","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130720723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Macroscopic imprints of ductile deformation 韧性变形的宏观印记

Principles of Rock Deformation and Tectonics Pub Date : 2021-08-31 DOI: 10.1093/oso/9780192843876.003.0005

J. Bouchez, A. Nicolas

{"title":"Macroscopic imprints of ductile deformation","authors":"J. Bouchez, A. Nicolas","doi":"10.1093/oso/9780192843876.003.0005","DOIUrl":"https://doi.org/10.1093/oso/9780192843876.003.0005","url":null,"abstract":"The fundamentals of structural geology are presented, namely, folds, planar structures (cleavage or schistosity, foliation) and linear ones (lineations), regarded as emblematic for geologists. Ductile imprints of folds, affecting stratified formations, combined with brittle imprints, often remain modest in terms of strain intensity. Folding is essentially inhomogeneous and often results from the buckling (bending) of the layers (or stratification) as a consequence of layer parallel compression. Folded structures are frequently accompanied by fractures. Hence they may be classified as brittle–ductile. They are mostly encountered at low depths and constitute the upper structural level of the Earth’s crust. Ductile deformation sensu stricto appears at the lower structural level. The macroscopic aspects of ductile deformations and their implications will be examined. The principal operating mechanism, crystalline plasticity, represents the mechanical aspect of deformation, sometime assisted by chemical aspects (pressure-solution). While homogeneous deformation constitutes our principal concern, heterogeneous deformation is often present, particularly when examined at fine scales. At low shear strain (γ‎ < 0.7, or θ‎ ~35°, equivalent to ~30% shortening), plastic deformation generally leads to a planar and a linear anisotropy strengthening with increasing deformation. At higher shear strain, any pre-existing planar structure becomes so stretched that it cannot be recognized. The new structure may be purely planar, purely linear or plano-linear. Lattice fabrics, appearing in rocks subjected to plastic deformation and resulting from deformation mechanisms at the grain-scale, are examined in detail in Chapter 6.","PeriodicalId":146168,"journal":{"name":"Principles of Rock Deformation and Tectonics","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131340657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0