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高压低温变质岩的抬升,归因于浮力、底辟或者水动力驱动的回流的作用。只要俯冲作用缓慢或者停止,向下的牵引减弱,浮力就可以使俯冲到地幔的物质回复。由于高压矿物组合的密度增加,地壳内的浮力将倒转,俯冲物质因此不能上升到地壳基底之上。底辟和水动力流作用要求介质密度低、粘度低,所以只能解释被带入流动物质中的较小的岩石块体的侵位。相关地区高压低温地体的构造环境,能够用屈服强度可以忽略的增生楔形体的力学行为来解释,此时,板底垫托作用是增生的主要方式.板底垫托作用从底部加厚了楔形体,并增加了它的表面坡度.即使聚敛作用正在进行,板底垫托作用也导致了楔形体上部的水平扩张。连续的底部板底垫托作用和上部扩张作用可以使最老的高压岩石在1000万年内上升到中等侵蚀的区域。只要楔形体底部的俯冲作用持续进行,地热梯度就不会松弛到正常值。增生楔形体的动力学过程解释:(a)高压-低温岩石在聚敛作用过程中常被抬升的证据。 (b)许多情况下没有高温组合显著的叠加。(c)最古老最高压的岩石位于造山楔形体后上部。(d)上覆岩石的构造厚度不足以解释变质作用。(e)切割部分变质带的变质后断层的常见产状。
The uplifting of high-pressure and low-temperature metamorphic rocks is attributed to buoyancy, diapirism or hydrodynamic driven reflow. As long as the subduction is slow or stops, the downward pull is weakened, and the buoyancy can make the matter subduct to the mantle. Because of the increased density of high-pressure mineral assemblages, the buoyancy in the crust will be reversed and therefore the subduction material must not rise above the crustal basement. The role of diapirs and hydrodynamic streams, which require low medium density and low viscosity, can only account for the emplacement of smaller rock masses brought into the flowing material. The tectonic setting of the high-pressure and low-temperature terrain in the relevant area can be explained by the mechanical behavior of the accretion wedge body with negligible yield strength. In this case, the plate underlayment is the main mode of proliferation, and the plate underlayment is thickened from the bottom Wedges, and increases its surface slope.While convergence is underway, the plate underlayers also cause a horizontal expansion of the upper part of the wedge. The continuous bottom plate underlay and top dilation allow the oldest high-pressure rock to rise to medium-eroded areas within 10 million years. As long as subduction at the bottom of the wedge continues, the geothermal gradient will not relax to normal. The dynamical process of the accretion wedge explains: (a) Evidence of high-pressure-low-temperature rocks that are often uplifted during the convergence process. (b) In many cases there is no significant overlap of high temperature combinations. (c) The oldest and highest highest pressure rock is located at the top of the orogen wedge. (d) The overburden rocks are not thick enough to account for metamorphism. (e) Common occurrences of faults after metamorphic belt cutting.