峨眉山玄武岩成因新思考——天体撞击的对冲聚合效应

New ideas on the genesis of Emeishan basalt——the effect of collision and coalescence caused by the collision of celestial objects

峨眉山玄武岩是目前被国内、国际唯一认可的大陆溢流玄武岩(CFB),关于其成因有很多解释,多数认为是"地幔柱"成因,但是也仅仅停留在地球化学的依据上,没有更多有说服力的证据。本文结合有关实验和数据论证"对冲聚合"理论的事实性和普遍性,认为地球另一端(撞击点)发生猛烈行星撞击,引起"对冲聚合"效应,造成对冲点巨大冲击能量重新聚合进而引起地震、火山活动和大规模岩浆溢流,撞击点和对冲点分别处在地球两端通过地心的对应点上,撞击发生时间和大规模岩浆活动几乎同时。为此,峨眉山玄武岩可能不是"地幔柱"成因,其冲破岩石圈形成溢流可能并非"地幔柱"头部作用造成穹窿上升、地壳减薄或者裂谷而喷溢,而可能是二叠纪/三叠纪时期地球另一端剧烈小行星撞击而引起"对冲聚合"效应形成上升通道,热流体因为外界扰动而喷溢。且本文也为探索"地幔柱"动力学机制和探讨地表热点分布以及和小行星撞击事件、全球生物大灭绝事件之间的联系,起到抛砖引玉的作用。

Emeishan basalt is the only kind of continental flood basalt (CFB)in China which is accredited by domestic and international society at present.The genesis of Emeishan basalt is broadly interpreted and most of the explanations support the theory of “mantle plume”.However,the existing explanations are all based only on the geochemistry yet without convincing evidences.This paper used the related experiments and data to demonstrate the factuality and universality of the "collision and coalescence" theory,and it believed that violent planetary collision which occurred on the other side of the earth(the impact point)caused the "colli-sion and coalescence" effect.In the collision point huge impact energy aggregates afresh,which arouses earthquakes,volcanic activities and overflowed massive lava.The impact point and the collision point are lo-cated at the each end of the axis which pass through the geocenter,and the impact and large-scale magmatic activity occur almost simultaneously.The author believed that the Emeishan basalts may not be of "mantle plume" genesis.Instead of being caused by the dome rising or crust thinning or rift valleys which result from the plume head effect of the"mantle plume",the overflow formed by magma escaped from the lithosphere may be the effusion of hydrothermal fluid disturbed by extraneous incidents,such as a rising channel created by"collision and coalescence" effect on account of a violent asteroid impact on the other side of earth in the period of Permian/Triassic.Moreover,this paper explored the dynamic mechanisms of the "mantle plume"and the distribution of the hot spots on the earth surface as well as their relations with the asteroid impact e-vents and the global mass extinction events.