Percolation of enriched melts during incremental open-system melting in the spinel field: A REE approach to abyssal peridotites from the Southwest Indian Ridge
Percolation of enriched melts during incremental open-system melting in the spinel field: A REE approach to abyssal peridotites from the Southwest Indian Ridge
复制标题
尖晶石场增量开放系统熔化过程中富集熔体的渗流：西南印度洋中脊深海橄榄岩的稀土元素方法
DOI：
10.1016/j.gca.2013.11.040
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发表时间：
2014
影响因子：
5
通讯作者：
M. Seyler
中科院分区：
文献类型：
--
作者：
D. Brunelli;E. Paganelli;M. Seyler
本文探讨了在开放体系中熔融作用对地幔残留物中稀土元素分布的影响。我们认为橄榄岩基质平衡的尖晶石领域占熔体流入部分熔融。的源，流入的熔体组合物和熔体添加速率以及不同的临界质量孔隙率在增量的情况下的影响的生育能力进行了测试。当一个相对富集的熔体进入系统，残余单斜辉石稀土元素归一化模式明显旋转周围的轻到中等的稀土元素，由于伴随着轻稀土元素的增加和重稀土元素的减少。当临界质量孔隙率相对于熔化程度较大时，这种效果增强。在这些情况下，系统更接近分批熔融行为，因为液体优先保留在基质中。这种几何形状暗示了熔体在深处的积聚。四个样本套房从西南印度洋脊被认为是。尖晶石领域平衡的单斜辉石在二辉橄榄岩和方辉橄榄岩显示疏浚规模的稀土元素组成的趋势，横切模型部分熔融轨迹。所观察到的当地趋势对应于旋转的稀土元素模式证明近批次插曲在subridge熔融历史和渗透的富集液体，其组成类似于石榴石场产生的熔体。
The effects of melting in an open-system scenario are here explored looking to the rare earth element (REE) distribution in mantle residues. We consider a peridotite matrix equilibrated in the spinel field accounting for melt inflow during partial melting. The fertility of the source, inflowing melt composition and melt addition rate as well as the effects of varying the critical mass porosity in an incremental scenario are tested. When a relatively enriched melt enters the system, residual clinopyroxene REE normalized patterns apparently rotate around a light to intermediate REE due to concomitant increase of the light REEs and decrease of the heavy REEs. This effect is enhanced when the critical mass porosity is large with respect to the degree of melting. In these cases the system approaches batch more than fractional melting behaviour because the liquid is preferentially retained in the matrix. This geometry is suggestive of melt accumulation at depth. Four sample suites from the Southwest Indian Ridge are considered. Spinel field equilibrated clinopyroxenes in lherzolites and harzburgites show dredge-scale REE compositional trends that crosscut model fractional melting trajectories. Observed local trends correspond to rotations of the REE patterns attesting for near-batch episodes in the subridge melting history and infiltration of enriched liquids whose composition resemble that of garnet field-generated melts.