Stress tectonic

Maximal horizontal stress (= minimal horizontal stress + tectonic stress) Tensile strength of rock material Pore pressure... 

Residual stresses in the formation, resulting from regional tectonic forces may cause the borehole to collapse or deform resulting in stuck pipe. Prevention sometimes high mud weights may help delay deformation of the bore hole. 

It is clear in Fig. 1.10 that the distribution of Kuroko deposits is restricted in a narrow zone in the Green tuff region which was called a Kuroko belt by Inoue (1969). This belt was formed by rapid subsidence under the extensional stress regime and is thought to have been a back-arc depression zone at middle Miocene age. The relationship between tectonic setting and formation of Kuroko deposits is discussed in section 1.5. 

The changes in stress fields, and intensities of igneous and hydrothermal activities seem to correlate to oscillatory motion of the Pacific plate (Jackson s episodes) (Jackson et al., 1975 Jackson and Shaw, 1975) (Masuda, 1984). Masuda (1984) and Takeuchi (1987) pointed out that the oscillatory motion of Pacific plate during the least 42 Ma correlates with magmatism, the intensity of tectonism, the change of stress field and the history of sedimentary basin in arc-trench system (Fig. 1.147). The above arguments also suggest that the mineralizations in arc and back-arc systems relate to the oscillatory motion of the Pacific plate. 

Figure 1.147. Jackson s curve and arc stress reorientations. Apparent swing motion of Pacific Plate (Jackson et al., 1975) and regional stress orientation at the Northeast Honshu convergent margin are illustrated in order to show their synchronous relationship. Dashed line represents the average trend of the Hawaiian volcanic chain. Pacific plate moves along the direction with fluctuation in reference to Hawaii Hot Spot. Vertically shaded parts of the graph indicate the climax phases of clockwise episodes . Lower part of the figure shows the phases and reversals in orientation of tectonic stress fields on the inner zone of Northeast Honshu Arc (Takeuchi, 1987).

During Miocene age most of this province was in a submarine environment. Violent submarine volcanism (bimodal and basic type) took place at Miocene age in this province. This geologic environment may be related to an extensional stress regime (Uyeda and Kanamori, 1979). The Kuroko deposits have been formed related to this tectonic situation. 

Kobayashi, Y. (1979) Early and middle Miocene dike swarms and regional tectonic stress field in the southwest Japan. Kazan, 2, 203-212 (in Japanese). 

Nakamura, K. (1977) Volcanoes as possible indicator of tectonic stress orientation — Principle and proposal. J. Volcano Geotherm. Res., 2, 1-16. 

Otsuki, K. (1989) Reconstruction of Neogene tectonic stress fields of northeast Honshu Arc from metalliferous veins. Geology Soc. Japan, Mem., 32, 281-304 (in Japanese with English abst.). 

Takeuchi, A. (1980) Tertiary stress field and tectonic development of the southern part of the northeast Honshu Arc. J. Geosci. Osaka City U., 213, 1-64. 

Takeuchi, A. (1981) Temporal changes of regional stress field and tectonics of sedimentary basin. J. Geol. Soc. Japan, 87, 737-751 (in Japanese). 

Takeuchi, A. (1987) On the episodic vicissitude of tectonic stress field of the Cenozoic Northeast Honshu arc, Japan. In Nasu, N. et al. (eds.), Formation of Active Ocean Margins, D. Reidel Publ., pp. 443-468. 

Thickening at the plate boundary is predicted to occur until gravitational forces balance tectonic stresses and elevation reaches an equilibrium. This balance of tectonic and gravitational forces causes the deformation to propagate away from the plate boundary and for a plateau to grow outward in a smooth fashion (England and Houseman 1988). However, if the entire lithosphere was shortened and thickened by a factor of 2, an appropriate number for the doublethickness crust of the Tibetan Plateau, then the surface of the plateau is predicted to rise no... 

Falsaperla S, Lanzafame G, Longo V, Spampinato S (1999) Regional stress field in the area of Stromboli (Italy) insights into structural data and crustal tectonic earthquakes. J Volcanol Geotherm Res 88 147-166... 

Mimran Y. (1975) Fabric deformation induced in Cretaceous chalks by tectonic stresses. Tectonophysics 26, 309-316. 

Thus, because of these empirical correlations, it may be possible, at least in principle, to estimate quantitatively the stress, temperature, and perhaps the strain-rate of a naturally deformed rock from measurements of dislocation density, subgrain size, and dynamically recrystallized grain size, together with Burgers vector determinations. However, these estimates will be questionable unless certain conditions are fulfilled. Some of the more important of these conditions will now be discussed before considering specific examples of the application of microstructural observations to tectonic problems. 

Carr, W. J., 1974, Summary of tectonic and structural evidence for stress orientation at the Nevada Test Site, U.S, Geol Survey Open-File Report 74-176. 

Sometimes tectonic stresses pulled the forming continents apart, creating cracks hundreds of miles or kilometers long in the crust. These cracks quickly filled with upwellingmagma to form dikes of solid rock. There are so many of these dikes of black rock that they are collectively called dike swarms. 

The cavity continues to expand in this manner until the pressure of the gases is balanced by the reaction of the rocks. This reaction can result either from the lithostatic pressure of the rocks, which depends on the explosion depth, or from the cohesive forces of the medium, or from residual stresses of tectonic origin which are the trace of the forces exerted on the medium during the formation of the massif. 

Sections 1.2.1 to 1.2.3 present the basic equations for groundwater flow through a representative elementary volume of the porous medium (Bear, 1972) under certain restrictive assumptions, such as isothermal and isochemical subsurface conditions and absence of changes in tectonic stress. 

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