大火成岩省及地幔动力学

Large Igneous Provinces and Mantle Dynamics

大火成岩省由一个体积巨大的、连续的、以富镁铁岩石占优势的喷出岩及其伴生的侵入岩组成 ,是一个全球现象。它包括大陆溢流玄武岩和伴生的侵入岩 ,火山被动边缘玄武岩 ,大洋高原、海岭、海山群和洋盆溢流玄武岩。OntongJava和Kerguelen_BrokenRidge大洋高原、北大西洋火山被动边缘、德干和哥伦比亚河大陆溢流玄武岩是 3个主要大火成岩省的典型代表。各种不同的大火成岩省在时空分布及组成上都具有相似性 ,它们具有非常大的体积、高的喷发速率 ,岩石类型以拉斑玄武岩为主。大火成岩省代表了地球上已知的最大的火山岩浆活动 ,记录了物质和能量从地球内部向外的大量转换。大火成岩省难以用板块构造来解释 ,可用热柱模式来解释 ,通常被认为是与来自下地幔的热柱“头”有关。大火成岩省是地球动力学过程在地壳的表现 。

As a global phenomenon, large igneous provinces (LIPs) are continuums of voluminous magnesium_rich and iron_rich effusive rocks, and include continental flood basalts and associated intrusive rocks, volcanic passive margins, oceanic plateaus, submarine ridges, seamount groups and ocean basin flood basalts. The representatives of the three major categories are Ontong Java and Kerguelen_Broken Ridge oceanic plateaus, North Atlantic volcanic passive margins, and Deccan and Columbia River continental flood basalts. Various LIPs have important temporal, spatial and compositional similarities, characterized exclusively by huge melt volume, high eruption rates and preponderant tholeiite. LIPs represent the largest known volcanic episode on the earth and record the outward significant transfer of material and energy from the Earth's interior. As they cannot be easily explained by plate tectonics, the mantle plume hypothesis is widely applied to interpret the origin of many large igneous provinces. In the thermal plume model, LIPs and many associated hotspot tracks have been ascribed to the melting of a large plume head and a narrow tail respectively. LIPs are crustal manifestations of dynamic processes in the Earth's mantle, and hence LIP parameters may be employed as boundary conditions to invert such processes.