The distribution of chalcophile and platinum-group elements in the UG-2 chromitite layer of the Bushveld Complex
The distribution of chalcophile and platinum-group elements in the UG-2 chromitite layer of the Bushveld Complex
复制标题
Bushveld 杂岩体 UG-2 铬铁矿层中亲铜元素和铂族元素的分布
DOI：
10.2113/gsecongeo.81.5.1080
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发表时间：
1986
期刊：
影响因子：
5.8
通讯作者：
S. Hiemstra
中科院分区：
文献类型：
--
作者：
S. Hiemstra
UG-2铬铁矿样品包含两个序列，其中Cu，Ni，S，Pt，Pd，Rh，Ru和Ir的浓度符合根据瑞利定律的分馏过程。这两个层序之后都有其他的层序，它们的走向几乎是水平的。从符合瑞利定律的层序中，人们可以计算出产生UG-2层的岩浆柱的可能厚度、总体分布系数和所涉及元素的原始浓度之间的关系。看来这些元素是从一层薄得令人惊讶的岩浆中提取出来的。在第一和第二旋回之间，某些元素被亏损，而另一些元素被富集，这表明新岩浆的隆起，而不是部分亏损的老岩浆通过类似对流翻转的过程再循环。S和亲铜元素Cu和Ni与铂族元素以相同的方式同时富集的事实表明，可能涉及同一捕收剂。因此硫化物不可能作为铂族元素的收集剂。据认为，铬铁矿，或铬铁矿的前体，以某种方式参与了收集过程。
A UG-2 chromitite sample contains two sequences in which the concentrations of Cu, Ni, S, Pt, Pd, Rh, Ru, and Ir conform to a process of fractionation according to the Rayleigh law. Both of these sequences are followed by others in which the trends are almost horizontal.From the sequences that conform to the Rayleigh law one can calculate the relations between the possible thicknesses of the magma column that gave rise to the UG-2 layer, the bulk distribution coefficients, and the original concentrations of the elements involved. It appears that the elements were withdrawn from a surprisingly thin layer of magma. Between the first and the second cycles certain elements have been depleted and others enriched, which indicates a heave of new magma rather than the recirculation of old partly depleted magma by a process like convective overturn.The fact that S and the chalcophile elements Cu and Ni were concentrated in the same way and at the same time as the platinum-group elements shows that the same collector was probably involved. Therefore sulfide could not have acted as a collector for the platinum-group elements. It is thought that chromite, or a precursor of chromite, was involved in some way with the collection process.