Inter-element fractionation of highly siderophile elements in the Tonga Arc due to flux melting of a depleted source
Inter-element fractionation of highly siderophile elements in the Tonga Arc due to flux melting of a depleted source
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DOI：
10.1016/j.gca.2012.03.025
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发表时间：
2012-07-15
影响因子：
5
通讯作者：
Arculus, Richard J.
中科院分区：
文献类型：
--
作者：
Dale, Christopher W.;Macpherson, Colin G.;Arculus, Richard J.
高度亲铁元素浓度（HSEs：Os，Ir，Ru，Pt，Pd和Re）已被确定为一套新鲜的，海底镁铁质熔岩从北方汤加弧前和新生的弧后Fonualei扩展中心（FSC）。在此之前，汤加地幔楔的熔融耗尽与高度的流体熔融相结合，被认为在几个弧和FSC位置产生了玻安质岩浆。因此，这个弧系统提供了一个机会，以评估流体流动性的HSEs和调查的影响，流体引起的熔融和前熔体耗尽HSE行为在地幔熔融和岩浆evolution.Tongan熔岩显示极端富集的Pt（2.5-32纳克/克）和Pd超过Os（0.002-0.6纳克/克），Ir和Ru，显着大于玄武岩从大洋中脊。岩浆演化增加了分馏的程度，导致在含MgO的弧前样品中记录到最高的Pt/Ru比值（>300
Highly siderophile element concentrations (HSEs: Os, Ir, Ru, Pt, Pd, and Re) have been determined for a suite of fresh, submarine mafic lavas from the northern Tonga Arc front and the nascent backarc Fonualei Spreading Centre (FSC). Prior melt depletion of the Tongan mantle wedge combined with a high degree of fluid fluxed melting is thought to have produced boninitic magmas at several arc and FSC locations. As such, this arc system provides an opportunity to assess the fluid mobility of HSEs and to investigate the effects of fluid-induced melting and prior melt depletion on HSE behaviour during both mantle melting and magma evolution.Tongan lavas display extreme enrichment of Pt (2.5-32 ng/g) and Pd over Os (0.002-0.6 ng/g), Ir, and Ru, significantly greater than basalts from mid-ocean ridges. Magma evolution increases the degree of fractionation, resulting in the highest recorded Pt/Ru ratios (>300) in arc front samples with MgO