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51.
52.
大陆岩石圈流变学研究 总被引:2,自引:1,他引:2
简单介绍了流变学的概念和两种基本研究方法,基于大陆岩石圈较大洋岩石圈有更为复杂的流变特征客观事实,指出研究大陆岩石圈流变学的重要性,并提出几个主要的研究方向和领域。 相似文献
53.
泥石流固体颗粒级配倒置,影响流速垂线分布、流态与冲击力,是一个十分重要的问题。本文根据力学及流变学对泥石流固体颗粒级配倒置进行了解释,对于泥石流运动机理的认识是有裨益的。 相似文献
54.
综述了高压超高压变质岩带的基本构造特征,认为运用体粘滞性流变学理论可以很好地解释高压超高压变质岩的发育过程及其抬升-剥露动力学机制。 相似文献
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天山造山带构造环境复杂,活动断裂带和强震分布广泛,且主要分布于阿尔泰山、天山、西昆仑—帕米尔弧形构造带上,尤以天山地区最为集中.迄今为止,天山造山带地区的主要断裂带的活动特征与孕震应力场特征之间的动力学机理尚未有清晰的认识.本文以GPS等实际观测数据为约束,建立有限元数值模型,计算了研究区域地壳形变、应力/应变积累速率、弹性应变能密度以及库仑应力变化率等关键因素.模拟计算结果显示地表速度场与研究区域实际GPS观测值基本一致,且主要断裂带上弹性应变能密度分布与实际地震活动性也基本吻合,验证了数值模型和结果的可靠性.结合最新的观测和数值模拟结果分析发现,研究区的断层和地震活动性主要受控于近南北向的主压应力,与主要观测特征相一致.同时,帕米尔高原北部边界带—塔什库尔干断裂(TKF)、天山造山带南边界的东侧—迈丹断裂(MDF)、兴地断裂(XDF)库仑应力增大明显,在未来强震发生的可能性较高,应予密切关注. 相似文献
57.
The Role of History-Dependent Rheology in Plate Boundary Lubrication for Generating One-Sided Subduction 总被引:1,自引:0,他引:1
Michio Tagawa Tomoeki Nakakuki Masanori Kameyama Fumiko Tajima 《Pure and Applied Geophysics》2007,164(5):879-907
We have developed a two-dimensional dynamical model of asymmetric subduction integrated into the mantle convection without
imposed plate velocities. In this model we consider that weak oceanic crust behaves as a lubricator on the thrust fault at
the plate boundary. We introduce a rheological layer that depends on the history of the past fracture to simulate the effect
of the oceanic crust. The thickness of this layer is set to be as thin as the Earth's oceanic crust. To treat 1-kilometer
scale structure at the plate boundary in the 1000-kilometer scale mantle convection calculation, we introduce a new numerical
method to solve the hydrodynamic equations using a couple of uniform and nonuniform grids of control volumes. Using our developed
models, we have systematically investigated effects of basic rheological parameters that determine the deformation strength
of the lithosphere and the oceanic crust on the development of the subducted slab, with a focus on the plate motion controlling
mechanism. In our model the plate subduction is produced when the friction coefficient (0.004–0.008) of the modeled oceanic
crust and the maximum strength (400 MPa) of the lithosphere are in plausible range inferred from the observations on the plate
driving forces and the plate deformation, and the rheology experiments. In this range of the plate strength, yielding induces
the plate bending. In this case the speed of plate motion is controlled more by viscosity layering of the underlying mantle
than by the plate strength. To examine the setting of the overriding plate, we also consider the two end-member cases in which
the overriding plate is fixed or freely-movable. In the case of the freely-movable overriding plate, the trench motion considerably
changes the dip angle of the deep slab. Especially in the case with a shallow-angle plate boundary, retrograde slab motion
occurs to generate a shallow-angle deep slab. 相似文献
58.
Experimental Investigation of Eclogite Rheology and Its Fabrics at High Temperature and Pressure 总被引:7,自引:0,他引:7
Eclogite plays an important role in mantle convection and geodynamics in subduction zones. An improved understanding of processes in the deeper levels of subduction zones and collision belts requires information on eclogite rheology. However, the deformation processes and associated fabrics in eclogite are not well understood. Incompatible views of deformation mechanism have been proposed for both garnet and omphacite. We present here deformation behaviour of eclogite at temperatures of 1027–1427 °C, confining pressures of 2.5–3.5 GPa, and strain rates of 1 × 10?5 s?1 to 5 × 10?4 s?1. We obtained a power‐law creep for the high temperature and pressure deformation of a ‘dry’ eclogite (50 vol.% garnet, 40% omphacite and 10% quartz) with A = 103.3 ± 1.0, n = 3.5 ± 0.4, ΔE =403 ± 30 KJ mol?1 and ΔV = 27.2 cm3 mol?1. The two principal minerals of eclogite have greatly different strengths. Progressive increase of garnet results in a smooth increase in strength. Analysis by electron back‐scattered diffraction shows that: (1) garnet displays pole figures with near random distributions of misorientation angle under both dry and wet conditions; (2) omphacite shows pronounced lattice preferred orientations (LPOs), suggesting a dominant dislocation creep mechanism. Further investigation into the water effects on eclogite show: (3) water content does not influence the style of omphacite fabric but increases slightly the fabric strength; (4) grain boundary processes dominate the deformation of garnet under high water fugacity or high shear‐strain conditions, yielding a random LPO similar to that of non‐deforming garnet, despite the strong shape preferred orientation (SPO) observed. {110} [001] slip may dominate the deformation of rutile. Quartz displays complicated and inconsistent LPOs in eclogite. These results are remarkably similar to observations from deformed eclogites in nature. 相似文献
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60.
岩石圈流变性取决于岩石圈的地热状态、物质组成和结构,并量化为岩石圈总强度。沉积盆地的沉降和抬升是地球最上层流变带形变的响应,岩石圈板块对构造应力的响应在很大程度上取决于岩石圈流变性在横向和纵向上的不均一性。辽西、辽北、松辽盆地区岩石圈流变性存在明显差异,因而岩石圈总强度明显不同,在晚中生代伸展过程中,变形方式、变形幅度不同,分别形成了断陷盆地、多断少坳型盆地和断坳型盆地。 相似文献