Mantle plume-stagnant slab interaction controls the generation of a mixed mantle source for continental intraplate basalts
Mantle plume-stagnant slab interaction controls the generation of a mixed mantle source for continental intraplate basalts
复制标题
地幔柱-静止板片相互作用控制大陆板内玄武岩混合地幔源的产生
DOI：
10.1016/j.lithos.2022.106795
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发表时间：
2022
期刊：
影响因子：
3.5
通讯作者：
Pham Nhu Sang
中科院分区：
文献类型：
--
作者：
Xun Yu;Zhifei Liu;Gang Zeng;Wenrong Cao;Rithy Meas;Van Long Hoang;Pham Nhu Sang
来自欧亚大陆东南部的大陆板内玄武岩显示出洋岛玄武岩样的地球化学特征和不均匀的同位素组成，表明同位素富集源和贫化端元源区之间存在混合。尽管这些玄武岩中与大洋地壳再循环有关的同位素富集端元(S)已被研究，但其贫化端元(S)的性质尚不清楚。本文介绍了柬埔寨东南部玄武岩的地球化学特征，并与南中国海区其他新生代板内玄武岩进行了对比。这些玄武岩具有低Ce/Pb和Nb/Th比值，中等的87Sr/86Sr(~0.7040)和εNd(~+5)，高的εHf(~+9.5)和略正的ΔεHf值。这些化学和同位素特征与枯竭的局部软流圈不一致。我们认为很可能来自下地幔物质的类FOZO组分代表了低Ce/Pb组分。结合地球物理观测，我们认为南中国海区这些板内玄武岩的形成受控于上升地幔热柱与停滞板块之间的相互作用。这项研究强调了地幔过渡带中的停滞板块在改变地幔热柱的成分，最终导致上地幔不均匀方面的重要作用。·来自南中国海区的板内玄武岩具有共同的地幔来源。·共享的地幔来源类似FOZO，支持地幔热柱的影响。·地幔热柱-滞流板相互作用可以改变上地幔的非均质性。·地幔中停滞不前的板块在化学和物理上影响着上升的热柱。
Continental intraplate basalts from southeastern Eurasia show ocean island basalt-like geochemical signatures and heterogeneous isotopic compositions suggesting mixing between isotopically enriched and depleted end-member sources. Although the isotopically enriched end-member(s) in these basalts which are related to oceanic crustal recycling have been investigated, the nature of the isotopically depleted end-member(s) remains unclear. We present geochemical characteristics of the southeast Cambodia basalt and compare them with other Cenozoic intraplate basalts in the South China Sea region. All these basalts contain a component with low Ce/Pb and Nb/Th ratios, moderate 87 Sr/ 86 Sr (~0.7040) and ε Nd (~ + 5), high ε Hf (~ + 9.5), and slightly positive Δε Hf value. These chemical and isotopic signatures are not consistent with the depleted local asthenosphere. We suggest a FOZO-like component, which is most likely derived from lower mantle material, represents the low-Ce/Pb component. Combined with geophysical observations, we propose that the interaction between the upwelling mantle plume and the stagnant slabs controls the formation of these intraplate basalts from the South China Sea region. This study highlights the important role of stagnant slabs in the mantle transition zone in modifying the compositions of mantle plumes, ultimately resulting in upper mantle heterogeneity. • Intraplate basalts from the South China Sea region have a shared mantle source. • The shared mantle source is FOZO-like supporting an influence from mantle plume. • Mantle plume-stagnant slab interaction can modify the upper mantle heterogeneity. • Stagnant slabs in the mantle affect the upwelling plume chemically and physically.