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首页> 外文期刊>Contributions to Mineralogy and Petrology >Magmatic processes and mantle heterogeneity beneath the slow-spreading northern Kolbeinsey Ridge segment, North Atlantic
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Magmatic processes and mantle heterogeneity beneath the slow-spreading northern Kolbeinsey Ridge segment, North Atlantic

机译：北大西洋北部缓慢扩张的北部柯尔本因西岭下的岩浆过程和地幔非均质性

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摘要

We present new data on mineralogical, major and trace element compositions of lavas from the northernmost segment of the Kolbeinsey Ridge (North Kolbeinsey Ridge, NKR). The incompatible element enriched North Kolbeinsey basalts lie on a crystal fractionation trend which differs from that of the other Kolbeinsey segments, most likely due to higher water contents (approx 0.2 percent) in the NKR basalts. The most evolved NKR magmas erupt close to the Jan Mayen Fracture Zone, implying increased cooling and fractionation of the ascending magmas. Mainly incompatible element-enriched basalts, as well as some slightly depleted lavas, erupt on the NKR. They show evidence for mixing between different mantle sources and magma mixing. North Kolbeinsey Ridge magmas probably formed by similar degrees of melting to other Kolbeinsey basalts, implying that no lateral variation in mantle potential temperature occurs on the spreading axis north of the Iceland plume and that the Jan Mayen Fracture Zone does not have a cooling effect on the mantle. Residual garnet from deep melting in garnet peridotite or from enriched garnet pyroxenite veins does not play a role. The incompatible element-enriched source has high Ba/ La and Nb/Zr, but must be depleted in iron. The iron-depleted mantle is less dense than surrounding mantle and leads to the formation of the North Kolbeinsey segment and its shallow bathymetry. The enriched NKR source formed from a relatively refractory mantle, enriched by a small degree melt rather than by recycling of enriched basaltic crust. The depleted mantle source resembles the mantle of the Middle Kolbeinsey segment with a depletion in incompatible elements, but a fertile major element composition.
机译：我们提供了有关科尔比辛西岭（North Kolbeinsey Ridge，NKR）最北段的熔岩的矿物学，主要和微量元素组成的新数据。富含不相容元素的北Kolbeinsey玄武岩的晶体分馏趋势与其他Kolbeinsey段的晶体分馏趋势不同，很可能是由于NKR玄武岩中的水含量较高（约0.2％）。演化最旺盛的NKR岩浆在Jan Mayen断裂带附近爆发，这意味着上升的岩浆的冷却和分馏增加。 NKR上主要喷出了不相容的富含元素的玄武岩以及一些贫化的熔岩。他们显示了不同地幔源与岩浆混合的证据。北部Kolbeinsey山脊岩浆可能是由与其他Kolbeinsey玄武岩相似的融化程度形成的，这意味着在冰岛羽状体以北的扩展轴上地幔势能没有横向变化，并且Jan Mayen断裂带对冰期没有冷却作用。地幔。石榴石橄榄岩深层融化或石榴石富氧辉石矿脉丰富而产生的残留石榴石不起作用。不兼容的元素富集源具有很高的Ba / La和Nb / Zr，但必须贫铁。贫铁地幔比周围的地幔密度低，并导致北科尔本西段的形成及其浅水深。浓集的NKR源是由相对难熔的地幔形成的，通过少量的熔融而不是通过浓集的玄武岩壳的再循环来浓集。枯竭的地幔来源类似于中柯尔本西段的地幔，其不相容元素被耗尽，但主要元素组成却富饶。

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