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921.
矿物反射光谱与反射旋转性的关系 总被引:1,自引:0,他引:1
根据对表达矿物的反射旋转及反射率公式的分析、对比,建立了反射旋转与反射率的关系。在此基础上建立了反射旋转色散与反射光谱的关系,继而得出了依据矿物的反射光谱、反射色及其颜色指数推断其反射旋转性质的方法与具体指标。 相似文献
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Interpretation of porphyroblast inclusion trails: limitations imposed by growth kinetics and strain rates 总被引:3,自引:0,他引:3
A. J. BARKER 《Journal of Metamorphic Geology》1994,12(5):681-694
Porphyroblast inclusion trails provide important information about the tectonometamorphic evolution of a metamorphic rock. However, there remains considerable controversy over whether porphyroblasts rotate during bulk non-coaxial deformation.
With reference to an area of the Scandinavian Caledonides and utilizing existing data from theoretical and experimental modelling, this study demonstrates that both 'straight' and 'S-shaped' inclusion trails are consistent with an interpretation in terms of syndeformational porphyroblast growth in a regime approximating to Newtonian simple shear. At crustal strain rates of 10-14 s-1 and porphyroblast growth times of 0.1–1.0 Ma, it is shown that a maximum of 5-9 angular rotation would occur during growth. At faster strain rates of 10-12 s-1 (e.g. those in a shear zone) porphyroblast angular rotations of 90 are shown to occur in 0.1–0.25 Ma (i.e. times comparable with or faster than porphyroblastesis). In view of this, 'S-shaped' inclusion trails are to be expected in porphyroblasts growing in active shear zones or other situations of high shear strain, whereas 'straight' inclusion trails can be interpreted as static overgrowth of an existing fabric or as syndeformational porphyroblastesis at low strain rates. 相似文献
With reference to an area of the Scandinavian Caledonides and utilizing existing data from theoretical and experimental modelling, this study demonstrates that both 'straight' and 'S-shaped' inclusion trails are consistent with an interpretation in terms of syndeformational porphyroblast growth in a regime approximating to Newtonian simple shear. At crustal strain rates of 10
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928.
江西地区气候变暖的增湿效应研究 总被引:4,自引:4,他引:4
应用江西地区近45 a的气温、降水、水汽压、蒸发量等常规观测资料,对比分析了气温与降水的关系,并试图在此基础上,利用第二类热成风螺旋度来理解江西地区自20世纪80年代中期以来气候变暖的湿旋转效应.研究结果发现,1959~1969年,江西地区气温降低时,第二类热成风螺旋度下降,导致降水量减少.1970~1983年,气温、降水和第二类热成风螺旋度的变化幅度均较小.1984~2003年,气温上升时,第二类热成风螺旋度上升,引起湿旋转作用加强,从而进一步加速大气中的水汽凝结,形成更多的降水;与此同时,地面蒸发量却减少,导致地表水增加,引发更多的地质灾害,造成更大的经济损失. 相似文献
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Factors α and β used in equivalent static analysis to account for natural and accidental torsion are evaluated with consideration of soil–structure interaction. The combined torsional effects of structural asymmetry and foundation rotation are examined with reference to a single monosymmetric structure placed on a rigid foundation that is embedded into an elastic half‐space, under to the action of non‐vertically incident SH waves. Dynamic and accidental eccentricities are developed such that when used together with the code‐specified base shear, the resulting static displacement at the flexible edge of the building is identical to that computed from dynamic analysis. It is shown that these eccentricities do not have a unique definition because they depend on both the selection of the design base shear and the criterion used for separation of the torsional effects of foundation rotation from those of structural asymmetry. Selected numerical results are presented in terms of dimensionless parameters for their general application, using a set of appropriate earthquake motions for ensuring generality of conclusions. The practical significance of this information for code‐designed buildings is elucidated. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
930.
Research on the dynamics of the South China Sea opening:Evidence from analogue modeling 总被引:15,自引:1,他引:15
SUN Zhen ZHOU Di ZHONG Zhihong XIA Bin QIU Xuelin ZENG Zuoxun JIANG Jianqun 《中国科学D辑(英文版)》2006,49(10):1053-1069
Independent of Indochina extrusion, the South China Sea experienced a process from passive continental rifting to marginal sea drifting. According to the fault patterns in the Beibu Gulf basin and the Pearl River Mouth basin, the continental rifting and early spreading stage from 32 to 26 Ma were controlled by extensional stress field, which shifted clockwise from southeastward to south southeastward. From 24 Ma on, the sea spread in NW-SE direction and ceased spreading at around 15.5 Ma. Integrated geological information with the assumption that the South China Sea developed along a pre-Cenozoic weakness zone, we did analogue experiments on the South China Sea evolu- tion. Experiments revealed that the pre-existing weakness zone goes roughly along the uplift zone between the present Zhu-1 and Zhu-2 depression. The pre-existing weakness zone is composed of three segments trending NNE, roughly EW and NEE, respectively. The early opening of the South China Sea is accompanied with roughly 15° clockwise rotation, while the SE sub-sea basin opened with SE extension. Tinjar fault was the western boundary of the Nansha block (Dangerous Ground), while Lupar fault was the eastern boundary of the Indochina, NW-trending rift belt known as Zengmu basin developed between above two faults due to block divergent of Indochina from Nansha. In the experiment, transtensional flower structures along NW-trending faults are seen, and slight inversion occurs along some NE-dipping faults. The existence of rigid massifs changed the orientations of some faults and rift belt, and also led to deformation concentrate around the massifs. The rifting and drifting of the South China Sea might be caused by slab pull from the proto South China Sea subducting toward Borneo and/or mantle flow caused by India-Asia collision. 相似文献