The thermochemical structure and evolution of Earth's mantle: constraints and numerical models
The thermochemical structure and evolution of Earth's mantle: constraints and numerical models
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地幔的热化学结构和演化：约束和数值模型
DOI：
10.1098/rsta.2002.1082
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Shunxing Xie
中科院分区：
文献类型：
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作者：
P. Tackley;Shunxing Xie
地球化学观察对地幔中的地球物理过程施加了几个限制，包括要求维持几个不同的储集层。地球物理限制将这些储集层的合理物理位置限制在较薄的基底层、大规模地幔隆起下孤立的深“堆”物质、整个地幔的高粘度斑点/梅状物或薄条，或这些物质的某种组合。介绍了一种能够模拟地幔热化学演化的数值模型。初步模拟比地球有更大的差异，但显示了一些拟议的热化学过程，包括通过地壳循环产生高μ地幔储备库，通过回收残余物产生高3He/4He储存库，尽管产生的高3He/4He物质往往聚集在靠近顶部的地方，那里大洋中脊熔融应该对其进行采样。如果原始物质以致密的基底层存在，它必须比俯冲地壳致密得多，才能保持其原始(如高-3He)特征。预计在不久的将来会取得很大进展。
Geochemical observations place several constraints on geophysical processes in the mantle, including a requirement to maintain several distinct reservoirs. Geophysical constraints limit plausible physical locations of these reservoirs to a thin basal layer, isolated deep ‘piles’ of material under large–scale mantle upwellings, high–viscosity blobs/plums or thin strips throughout the mantle, or some combination of these. A numerical model capable of simulating the thermochemical evolution of the mantle is introduced. Preliminary simulations are more differentiated than Earth but display some of the proposed thermochemical processes, including the generation of a high–μ mantle reservoir by recycling of crust, and the generation of a high–3He/4He reservoir by recycling of residuum, although the resulting high–3He/4He material tends to aggregate near the top, where mid–ocean–ridge melting should sample it. If primitive material exists as a dense basal layer, it must be much denser than subducted crust in order to retain its primitive (e.g. high–3He) signature. Much progress is expected in the near future.