不同时空背景幔源物质对比与华北深部岩石圈破坏和增生置换过程

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华北克拉通地幔破坏作用,使之成为世界研究大陆形成演化的最理想地区之一.但有关破坏机制、时限、范围及其动力学背景,甚至破坏前岩石圈状况等相关联问题都存争议.华北东部不同时代(如古生代、中生代和新生代)、位置(如地块内部与边缘、郯庐断裂带和重力梯度带)火山岩所携带捕虏体橄榄岩,及其南侧苏鲁-大别造山带地质体橄榄岩等直接的岩石圈地幔物质对比表明:华北古老岩石圈是不均一的、存在幔内薄弱带,中生代、新生代岩石圈减薄作用包括地幔伸展、熔体-岩石作用、不均匀侵蚀减薄与小幅增生增厚,从而实现难熔克拉通地幔被新生饱满岩石圈地幔置换作用等复杂过程.早中生代时,扬子大陆深俯冲碰撞引起华北岩石圈的完整性受影响甚至破坏、边缘受俯冲陆壳释放熔/流体交代改造、岩石圈地幔伸展和构造侵位以及受山根断离扰动软流圈物质上涌侵蚀等;早白垩世-早第三纪时,太平洋板块俯冲进一步扰动软流圈并强烈上涌侵蚀上覆岩石圈引起它的巨大减薄作用;晚第三纪以来上涌软流圈的热沉降作用带来小幅度岩石圈增生增厚过程,最终实现了已存岩石圈被新生地幔置换和岩石圈整体的减薄作用,并由此构成了陆内造山和克拉通盆地形成耦合过程的深部驱动力.郯庐等岩石圈深大断裂带是软流体物质上涌的良好通道,同时由于在岩石圈内部起通道作用的幔内薄弱带是不规则的,它们引导着软流圈物质侵蚀岩石圈和岩浆喷出地表的时间存在早、晚不一致现象.喷发时代为100Ma的玄武岩所捕获的橄榄岩主体是饱满的,说明华北东部的一些地区在此之前(如125~100Ma)曾有过地幔置换作用发生. The destructive effect of the North China craton on the mantle has made it one of the most ideal areas in the world to study the formation and evolution of the continent, but there are still controversies about the damage mechanism, time frame, scope and dynamics, and even the destruction of the former lithosphere. Permian xenoliths carried by volcanic rocks of different ages (such as Paleozoic, Mesozoic and Cenozoic) and volcanic rocks in the interior (such as the interior and margins of the block, Tanlu fault zone and gravity gradient zone) in the eastern part of North China and the Sulu-Dabie The contrast of the lithospheric mantle directly from the orogenic belts indicates that the ancient lithosphere in North China is heterogeneous with weak strata within the mantle, Mesozoic and Cenozoic lithospheric thinning effects include mantle extension, melt-rock interaction, Uneven erosion thinning and small thickening and thickening so as to realize the complex processes such as replacement of mantle lithosphere mantle by new born and full lithospheric mantle replacement.During the early Mesozoic, the deep subduction collision in the Yangtze continent caused or even destroyed the integrity of lithosphere in North China , The margin is affected by the subduction of the submarine crust, the replacement of melt / fluid, the lithospheric mantle extension and structural emplacement, and the disturbance of asthenosphere Upwelling and so on. From the Early Cretaceous to the Early Tertiary, the subduction of the Pacific Plate further perturbed the asthenosphere and strongly upwells the overlying lithosphere, causing great thinning effect. Upwelling asthenosphere since the Late Tertiary The thermal sedimentation brings about a small increase of lithospheric hyperplasia and thickening process. Finally, the existing lithosphere was replaced by the new-born mantle and the whole lithosphere thinning and thus formed the coupling process between the intracontinental orogenic craton and the craton basin Of the deep driving force.The Tanlu and other lithospheric deep fault zone is a good channel for soft fluid upwelling at the same time due to the channel within the lithosphere within the role of the channel is irregular within the weak zone, they guide the asthenosphere material There are early and late inconsistencies in the erosional lithosphere and magma spewing out of the surface.The body of the peridotite captured by basalts of 100 Ma during the Eruption Age is full, indicating that some areas in the eastern North China had (125 ~ 100 Ma) Mantle replacement occurred.
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