马里亚纳海沟Challenger Deep的岩石圈流变结构与动力学分析

发布时间：2018-01-13 02:27

本文关键词：马里亚纳海沟Challenger Deep的岩石圈流变结构与动力学分析　出处：《中国科学院大学学报》2017年03期 　论文类型：期刊论文

【摘要】：马里亚纳海沟是西太平洋板块边缘沟-弧-盆体系构造演化的关键地区,其南端的Challenger Deep不仅是地球表面最深点,也是马里亚纳海沟、马里亚纳岛弧、马里亚纳海槽、西马里亚纳洋脊和帕里西维拉海盆的构造汇聚点。开展岩石流变结构与动力学过程研究对于认识Challenger Deep的形成演化具有重要的科学意义。利用综合地球物理资料,通过对重、磁数据的计算分析,研究马里亚纳沟-弧-槽-盆系统的等效黏滞系数和岩石圈强度等流变学特征。利用地震资料,勾绘海沟之下贝尼奥夫带随深度变化的特征以及陡变形态。计算结果表明:对应马里亚纳海沟-岛弧-海槽系统,自由空气重力异常向东凸出,形成弧型异常区;区内异常表现为串珠状线性特征,异常值中间高,两侧低。不同深度岩石圈累积强度比值表明,海沟南北两侧地壳上硬下软,海沟中部地壳上软下硬。在给定应变速率条件下计算的等效黏滞系数东高西低,说明西侧构造体地壳比东侧构造体地壳更容易变形。Challenger Deep岩石圈强度较大,等效黏滞系数较高,具有上硬下软的流变学特征,为板块俯冲在该区的弯曲、撕裂与快速翻转提供了重要条件。地震与重力剖面分析表明,Challenger Deep处的岩石圈累积应力强度和有效粘滞系数条件,可以使马里亚纳海沟俯冲带在重力作用下弯曲、开裂,或部分向南翻转、变陡。
[Abstract]:The Mariana trench is the key area for the tectonic evolution of the trench-arc basin system on the edge of the western Pacific plate. The Challenger Deep at the southern end of the trench is not only the deepest point on the earth's surface. It is also the Mariana Trench, the Mariana Island Arc, and the Mariana trough. The tectonic convergence points of the Western Mariana Ridge and the Palissilla basin. The study of the rock rheological structure and dynamics process for the understanding of Challenger. The formation and evolution of Deep is of great scientific significance. Based on the calculation and analysis of gravity and magnetic data, the rheological characteristics of the Mariana trench-arc-trough basin system, such as equivalent viscosity coefficient and lithospheric strength, are studied. The characteristics of the Benioff belt under the trench and its abrupt variation are plotted. The results show that the gravity anomaly of free air protrudes eastward corresponding to the Mariana trench-island arc-trough system. Forming arc anomaly area; The anomalies in the area are characterized by beaded linear characteristics, high in the middle and low in both sides. The ratio of accumulative strength of lithosphere at different depths indicates that the crust is hard and soft on the north and south sides of the trench. In the middle of the trench, the crust is soft and hard. The equivalent viscosity coefficient calculated under the condition of given strain rate is high and low in the east and west. It shows that the crust of the western tectonic body is more easily deformed than that of the eastern tectonic body. The Deep lithosphere has a stronger strength and a higher equivalent viscosity coefficient, and it has the rheological characteristics of upper and lower hardness and softness. It provides important conditions for plate subduction in this area, such as bending, tearing and fast turning. The seismic and gravity profile analysis shows that. The conditions of accumulated stress intensity and effective viscosity coefficient of the lithosphere at Challenger Deep can cause the Mariana trench subduction zone to bend, crack or partially flip southward under the action of gravity. Steepen.
【作者单位】：中国科学院计算地球动力学重点实验室;中国科学院大学地球科学学院;中国科学院深海科学与工程研究所;
【基金】：国家自然科学基金(41574047,41430319,41174085,91228205) 中国科学院战略先导项目(XDA1103010102、XDB06030400);中国科学院创新团队项目(KZZD-EW-TZ-19)资助
【分类号】：P736.1
【正文快照】： Challenger Deep(海斗深渊)位于马里亚纳海沟岛弧体系南端的俯冲折转部位,它既位于全球最深海沟———马里亚纳海沟体系中最深的位置,又位于现今仍进行俯冲汇聚的海底活动构造区,因此是研究俯冲带-大洋岛弧-弧后盆地等相关动力学问题的关键地区。 1地质与地球物理背景马里

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