Mantle melting variation and refertilization beneath the Dragon Bone amagmatic segment (53°E SWIR): Major and trace element compositions of peridotites at ridge flanks
Mantle melting variation and refertilization beneath the Dragon Bone amagmatic segment (53°E SWIR): Major and trace element compositions of peridotites at ridge flanks
复制标题
龙骨无岩浆段（53°E SWIR）下的地幔熔化变化和再肥化：山脊侧面橄榄岩的主量和微量元素组成
DOI：
10.1016/j.lithos.2018.11.014
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发表时间：
2019
期刊：
影响因子：
3.5
通讯作者：
Dick, Henry
中科院分区：
文献类型：
--
作者：
Wang, Jixin;Zhou, Huaiyang;Salters, Vincent;Liu, Yang;Sachi-Kocher, Afi;Dick, Henry
低温岩石圈下地幔熔融机制的演化和再成矿过程在超低扩张脊处仍不清楚。以往的研究很少关注单一脊段侧翼橄榄岩所指示的地幔熔融的时间变化。本文对龙骨脊段近扩展轴和距脊轴数十公里的裂谷山的哈尔茨伯尔土进行了原位主量元素和微量元素分析。我们提出，龙骨地幔在较古老的高压下已经枯竭，在较低压力下在脊下上升之前，在脊下最近的融化过程中只产生了有限体积的融化。这一解释与龙骨碳酸盐的高度枯竭，几乎没有被困的熔体，以及海底薄的不连续火成岩壳相一致。比较来自山脊附近的橄榄岩和那些来自侧翼更远的橄榄岩表明，随着时间的推移，熔融状态逐渐缩小，目前形成了一个接近岩浆的部分。来自段端的橄榄岩很少受到后期再作用的影响，而来自段中心的橄榄岩则是高度枯竭的地幔残余物（类似于那些来自快速扩张脊的橄榄岩），它们持续着同融交代作用。
The evolution of the mantle melting regime and the process of refertilization beneath cold lithosphere remain ambiguous at ultraslow spreading ridges. Few previous studies were concerned with the temporal variations of mantle melting indicated by peridotites on the flank of a single ridge segment. Here, we present in-situ major and trace element analyses of harzburgites from the Dragon Bone ridge segment both from near the spreading axis and from rift mountains up to tens of kilometers from the ridge axis. We propose that the Dragon Bone mantle had been depleted anciently at higher pressures, prior to the recent ascent under the ridge at lower pressures, and only a limited volume of melt was generated during recent melting beneath the ridge. This interpretation is consistent with the high degree of depletion of the Dragon Bone harzburgites with little trapped melt, and thin discontinuous igneous crust on the seafloor. Comparison of peridotites from near-ridge locations with those further out on the flanks indicates that the melting regime has progressively shrunk over time creating at present a nearly amagmatic segment. Peridotites from segment ends are seldom affected by late-stage refertilization, while those from the segment center are highly depleted mantle residues (resembling those from fast spreading ridges) that sustainedsyn-melting metasomatism.
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DOI：
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发表时间：
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期刊：
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作者：
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