Ion microprobe study of plagioclase-basalt partition experiments at natural concentration levels of trace elements
Ion microprobe study of plagioclase-basalt partition experiments at natural concentration levels of trace elements
复制标题
DOI：
10.1016/s0016-7037(98)00047-7
复制
发表时间：
1998-04-01
影响因子：
5
通讯作者：
Drake, MJ
中科院分区：
文献类型：
--
作者：
Bindeman, IN;Davis, AM;Drake, MJ
本文利用Drake和Weill（1975）广泛引用的斜长石/熔体分配实验的样品，研究了微量元素在自然浓度水平下的斜长石/熔体分配。在这些实验中，用Sr、Ba、稀土元素（REE）和Y将样品装料掺杂至近似1wt%，但每个装料仅掺杂1至4种元素。因此，这些样品提供了一个机会，比较自然浓度水平的分配系数（D-L）与掺杂浓度水平的斜长石，熔体和温度相同的组合物。在四种不同的斜长石成分和温度下，用电子探针分析了17次斜长石-玻璃对的主要元素和一些掺杂的微量元素，用离子探针分析了未掺杂的Li、Be、B、F、Mg、P、Cl、K、Sc、Ti、V、Cr、Mn、Fe、Co、Ni、Rb、Sr、Y、Zr、Nb、Ca、Ba、La、Ce、Pr、Nd、Sm、Eu和Pb。分配的同价取代离子Sr 2+和Ba 2+显示掺杂和天然浓度水平之间没有差异。离子探针测得的D-L杂价取代离子RE 3+和Y 3+在自然浓度水平（0.3-3 ppm）的样品中掺杂的Sr或Ba的wt%水平高达三倍以上的掺杂浓度水平，不能解释的分析文物。在0.4 < X-An < 0.8的范围内，所有的微量元素D-L数据都表现出ln（D-L）= a* X-An + B* 和RT 1 n（D-L）= α X-An + B的线性关系。碱金属、碱土金属和镧系元素在每组元素中表现出相同类型的组成依赖性。斜率a* 和α随着每个价群内离子半径的增加而变化。这些组中的每一个的较小离子不显示或显示正斜率a* 和α;较大离子显示负斜率。斜率的大小与离子半径在同一价群内线性增加。这种关系允许外推和预测的组成依赖的元素的同一组的浓度不能在这项work.We测量RT ln（D-L）= α X-An + B关系的最佳拟合近似参数。这些可用于各种岩石学应用，以重建原生微量元素组成的母体熔体从斜长石结晶。版权所有（C）1998 Elsevier Science Ltd.
We present here a study of plagioclase/melt partitioning of trace elements at their natural concentration levels, using sample charges from the widely cited plagioclase/melt partitioning experiments of Drake and Weill (1975). In these experiments, sample charges were doped to similar to 1 wt% with Sr, Ba, rare earth elements (REE) and Y, but each charge was only doped with one to four elements. Thus, these samples provide an opportunity to compare partition coefficients (D-L) at natural concentration levels with those for doped concentration levels for the same composition of plagioclase, melt and temperature. Plagioclase-glass pairs of seventeen runs at four different plagioclase compositions and temperatures were analyzed by electron microprobe for major elements and some of the doped trace elements and by ion microprobe for undoped Li, Be, B, F, Mg, P, Cl, K, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Rb, Sr, Y, Zr, Nb, Ca, Ba, La, Ce, Pr, Nd, Sm, Eu, and Pb. Partitioning of the homovalent substituting ions Sr2+ and Ba2+ show no differences between doped and natural concentration levels. Ion microprobe measured D-L heterovalent substituting ions REE3+ and Y3+ at natural concentration levels (0.3-3 ppm) in samples doped with wt% levels of Sr or Ba are up to three times higher than at doped concentration levels and cannot be explained by analytical artifacts. We discuss possible reasons for this.All trace element D-L data show linear relationships of the forms ln (D-L) = a* X-An + b* and RT 1n (D-L) = alpha X-An + b in 0.4 < X-An < 0.8 range. Alkalies, alkaline earths, and lanthanides exhibit the same type of compositional dependence within each group of elements. Slopes a* and alpha vary with the increase of the ionic radius within each valence group. The smaller ions of each of these groups exhibit no or positive slopes a* and alpha; the larger ions show negative slopes. The magnitudes of the slopes increase linearly with ionic radii within the same valence group. This relationship allows extrapolation and prediction of the compositional dependence of elements of the same group whose concentrations could not be measured in this work.We present best fit approximation parameters for the RT ln (D-L) = alpha X-An + b relationship. These can be used in various petrologic applications to reconstruct the primary trace elemental composition of the parental melt from which plagioclase crystallized. Copyright (C) 1998 Elsevier Science Ltd.