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本文通过整理近年来蒙古-贝加尔裂谷有关地幔柱的研究成果,从重力异常、层析成像和接受函数等方面分析贝加尔地区上地幔的各向异性特性,并重点介绍了中蒙合作项目的深部构造研究成果,探究地幔柱在蒙古-贝加尔裂谷形成中的作用.研究发现:贝加尔裂谷区上涌物质来源于410km不连续面之下和660km不连续面之上,低速异常延伸至贝加尔裂谷下的地幔转换地带,可能是地幔柱低速异常的反映.速度异常还可能与应力环境有关,东部Pn速度低值异常与太平洋板块俯冲动力作用引起的地壳的伸展减薄和岩浆活动有关,西部Pn速度高值异常则是India板块强烈碰撞挤压动力作用所形成.蒙古-贝加尔裂谷带起源受岩石圈扩张和岩石圈不均匀性的综合影响,裂谷下的低速区存在偏转的地幔柱,偏转的地幔柱在India-Asia板块碰撞引起形变的远场力的帮助下,成为贝加尔裂谷演化和发展的主要成因之一.
This paper analyzes the anisotropy characteristics of upper mantle in Baikal region from the gravity anomaly, tomography and acceptance function by sorting out the research results of mantle plume in the Mongolia-Baikal rift in recent years, and focuses on the deep part of Sino-Mongolian cooperation project Constructed the research results and explored the role of mantle plume in the Mongolian-Baikal rift formation.It is found that the upwelling material in the Baikal rift region originates above the discontinuity of 410 km and the discontinuity of 660 km, and the low-velocity anomaly extends to the Baikal rift The mantle transition zone beneath the valley may be a reflection of the low-velocity mantle plume Anomalies may also be related to the stress environment. The low Pn velocity anomaly in the east is related to the crustal extension and thinning caused by the Pacific plate subduction and the magmatic activity. The high Pn velocity anomaly is formed by intensive collision and extrusion of the India plate.The origin of the Mongolia-Baikal rift zone is affected by the combination of lithospheric expansion and lithospheric heterogeneity, and the mantle plume , The deflection of the mantle plumes, with the help of the far-field forces resulting from the collision of the India-Asia plate collision, became the evolution and evolution of the Baikal rift One of the main causes of the show.