The primordial chondritic nature and large-scale heterogeneities in the mantle: evidence from high and low partition coefficient elements in oceanic basalts
The primordial chondritic nature and large-scale heterogeneities in the mantle: evidence from high and low partition coefficient elements in oceanic basalts
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地幔中的原始球粒陨石性质和大尺度异质性：来自大洋玄武岩中高分配系数和低分配系数元素的证据
DOI：
10.1098/rsta.1980.0210
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发表时间：
1980
期刊：
影响因子：
--
通讯作者：
M. Treuil
中科院分区：
文献类型：
--
作者：
H. Bougault;J. Joron;M. Treuil
通过对大西洋和太平洋不同地区大洋玄武岩中微量元素的测量，研究了地幔的大尺度不均匀性。该研究依赖于元素的物理化学性质及其根据分配系数的分类。高分配系数的元素（钴，镍，铬）的浓度在橄榄岩是不敏感的固液平衡（部分熔融），因此地幔应该是均匀的，相对于这些元素。具有相同或非常相似的低分配系数的元素（Y/Tb，Zr/Hf和Nb/Ta）的比例是恒定的，在所有研究的样品中，尽管它们的大的浓度范围。这些比值与地幔的热膨胀比相等，有利于原始地幔的热膨胀性质。La/Ta比值有两个值，9或18，与地形密切相关（地形高点为9）。当两种亲湿岩浆元素的分配系数之间的差异增大时，所观察到的它们的比值的局部变化可以被解释为地幔源区的局部不均匀性或岩浆过程（例如部分熔融）的影响。
Large-scale heterogeneities in the mantle are investigated through trace elements measured in oceanic basalts from different locations in the Atlantic and Pacific oceans. The study relies upon the physico-chemical properties of the elements and their classification according to their partition coefficients. High partition coefficient elements (Co, Ni, Cr) have concentrations in peridotite that are not sensitive to solid-liquid equilibrium (partial melting); the mantle should therefore be homogeneous with respect to these elements. The ratios of elements that have equal or very similar low partition coefficients (Y/Tb, Zr/Hf and Nb/Ta) are constant in all samples studied, despite their large concentration range. These ratios are equal to chondritic ratios and favour a chondritic nature for the primordial mantle. The La/Ta ratio shows two values, either 9 or 18, which are closely related to topography (9 for topographic highs). When the difference between partition coefficients of two hygromagmaphilic elements increases, the local variations observed for their ratio can be interpreted either as local heterogeneities of mantle sources or as the effect of magmatic processes (e.g. partial melting).