Generation of hydrous-carbonated plumes in the mantle transition zone linked to tectonic erosion and subduction
Generation of hydrous-carbonated plumes in the mantle transition zone linked to tectonic erosion and subduction
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DOI：
10.1016/j.tecto.2015.08.005
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发表时间：
2015-11
期刊：
影响因子：
2.9
通讯作者：
I. Safonova;S. Maruyama;K. Litasov
中科院分区：
文献类型：
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作者：
I. Safonova;S. Maruyama;K. Litasov
本文提出了一个连接(1)太平洋型辐合边缘的地幔过渡带（MTZ）中含水碳酸柱（HCPs）生成的模型；（二）在挥发物（水、二氧化碳）、俯冲的花岗岩物质和大洋板块的影响下，中过渡带熔体的产生；（三）中亚中新生代板块内岩浆活动。该模型基于从地质学、岩石学、地震层析成像和数值模拟中获得的四组证据。后中新世亚洲周围太平洋型边缘的双面俯冲向深部地幔提供了含水碳酸化的洋壳和陆壳物质，这些物质在410 ~ 660 km的MTZ内聚集。西太平洋洋内弧的直接俯冲和辐合边缘上壁的构造侵蚀提供了向中过渡带输送地壳物质的途径。富集铀钍钾的大陆物质在中过渡带中积累，可以作为额外的热源。大陆地壳物质俯冲的证据来自地震层析成像和数值模拟数据。由蛇纹岩、水合沉积物、碳酸盐和碳化玄武岩组成的俯冲洋板向深部地幔提供水和二氧化碳，使之发生交代作用。挥发物的存在可以降低熔融温度，而俯冲的地壳物质的存在可以作为额外的加热器，可以协同触发hcp的产生。这些hcp可诱发地幔上涌、交代地幔和俯冲MORB板块的熔融、熔体的上升、表面裂陷以及基性和双峰型火山系列的形成。此外，它们对超大陆旋回也有贡献。中亚和东亚下MTZ的hcp形成了构造体制由挤压向张拉的转变，形成了大量中新生代板内火山场。
This paper presents a model for the generation of hydrous-carbonated plumes (HCPs) in the mantle transition zone (MTZ) linking (i) the Pacific-type convergent margins; (ii) melt generation in the MTZ under the influence of volatiles (water, carbon dioxide) and subducted granitic material and oceanic slabs and (iii) the Meso-Cenozoic intra-plate magmatism in Central Asia. The model is based on four groups of evidences obtained from geology, petrology, seismic tomography and numerical simulations. The double-sided subduction at the Pacific-type margins around post-Miocene Asia supplies hydrated-carbonated oceanic crust and continental crust materials down to the deep mantle, which accumulate in the MTZ at 410–660 km. The delivery of crustal material to the MTZ is provided by the direct subduction of intra-oceanic arcs in the Western Pacific and by the tectonic erosion of convergent margin hanging walls. The U-Th-K–enriched continental material accumulated in the MTZ can serve an additional source of heat. Evidence for the subduction of continental crust materials comes from seismic tomography and numerical modelling data. The subducting oceanic slab consisting of serpentinites, hydrated sediments, carbonates and carbonatized basalts can supply water and carbon dioxide to the deep mantle and metasomatize it. The presence of volatiles, which can reduce melting temperature, and the presence of the subducted crustal material, which may serve an additional heater, can synergistically trigger the generation of HCPs. Those HCPs can induce mantle upwelling, melting of the metasomatized mantle and subducted MORB slabs, ascent of melts, surface rifting and formation of mafic and bimodal volcanic series. In addition, they can contribute to the supercontinent cycle. The HCPs generated in the MTZ beneath Central and East Asia resulted in a shift of the tectonic regime from transpression to transtension and in the formation of numerous Meso-Cenozoic intra-plate volcanic fields.