Volatile composition of microinclusions in diamonds from the Panda kimberlite, Canada: Implications for chemical and isotopic heterogeneity in the mantle
Volatile composition of microinclusions in diamonds from the Panda kimberlite, Canada: Implications for chemical and isotopic heterogeneity in the mantle
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加拿大熊猫金伯利岩钻石中微包裹体的挥发性成分：对地幔中化学和同位素异质性的影响
DOI：
10.1016/j.gca.2008.12.025
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发表时间：
2009
影响因子：
5
通讯作者：
Burgess R
中科院分区：
文献类型：
--
作者：
Burgess R
为了更好地研究与钻石生长有关的流体的组成和来源，我们对加拿大西北地区熊猫金伯利岩的单个含微包裹体钻石碎片进行了稀有气体（He和Ar）、C和N同位素、K、Ca和卤素（Cl、Br、I）的联合测定。熊猫钻石中卤素和惰性气体的流体浓度比典型的上地幔丰度丰富了几个数量级。稀有气体、C、N同位素比值（3He/4He= 4-6Ra,40Ar/36Ar=2 - 3万，δ13C= - 4.5‰~ - 6.9‰，δ15N= - 1.2‰~ - 8.8‰）在纤维状金刚石测定的世界范围内，与大洋中脊玄武岩（MORB）源值相近。钻石的高36ar含量（>1×10−9cm3/g）至少比以前报道的任何地幔样品高一个数量级，并使次大陆岩石圈地幔的36ar含量估计为~ 0.6×10−12cm3/g，再次类似于MORB源的估计。根据Ca-K-Cl组成区分的三种流体类型与以前在世界各地的钻石研究中发现的碳酸岩、硅和盐端元相一致。这些流体端元也具有不同的卤素比率（Br/Cl和I/Cl）。俯冲的海水衍生卤素的作用最初被用来解释钻石中卤素比例的一些变化，但不被认为是流体形成的一个重要组成部分。相反，认为原始地幔比的大卤素分馏发生在形成硅流体的流体-熔体分配过程中，以及不混溶的盐流体分离过程中。
In order to better investigate the compositions and the origins of fluids associated with diamond growth, we have carried-out combined noble gas (He and Ar), C and N isotope, K, Ca and halogen (Cl, Br, I) determinations on fragments of individual microinclusion-bearing diamonds from the Panda kimberlite, North West Territories, Canada. The fluid concentrations of halogens and noble gases in Panda diamonds are enriched by several orders of magnitude over typical upper mantle abundances. However, noble gas, C and N isotopic ratios (3He/4He=4–6Ra,40Ar/36Ar=20,000–30,000, δ13C=−4.5‰ to −6.9‰ and δ15N=−1.2‰ to −8.8‰) are within the worldwide range determined for fibrous diamonds and similar to the mid ocean ridge basalt (MORB) source value. The high36Ar content of the diamonds (>1×10−9cm3/g) is at least an order of magnitude higher than any previously reported mantle sample and enables the36Ar content of the subcontinental lithospheric mantle to be estimated at ∼0.6×10−12cm3/g, again similar to estimates for the MORB source. Three fluid types distinguished on the basis of Ca–K–Cl compositions are consistent with carbonatitic, silicic and saline end-members identified in previous studies of diamonds from worldwide sources. These fluid end-members also have distinct halogen ratios (Br/Cl and I/Cl). The role of subducted seawater-derived halogens, originally invoked to explain some of the halogen ratio variations in diamonds, is not considered an essential component in the formation of the fluids. In contrast, it is considered that large halogen fractionation of a primitive mantle ratio occurs during fluid–melt partitioning in forming silicic fluids, and during separation of an immiscible saline fluid.
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DOI：
--
发表时间：
2007
期刊：
影响因子：
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作者：
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作者：
D. Zedgenizov;S. Rege;W. Griffin;H. Kagi;V. Shatsky
通讯作者：
V. Shatsky
影响因子：
5.3
作者：
E. Tomlinson;A. Jones;J. Harris
通讯作者：
E. Tomlinson;A. Jones;J. Harris
影响因子：
5.3
作者：
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通讯作者：
S. Boyd;C. Pillinger;H. Milledge;M. Seal
影响因子：
5
作者：
Bureau, H;Métrich, N
通讯作者：
Métrich, N