Calcium isotopic composition of mantle xenoliths and minerals from Eastern China
Calcium isotopic composition of mantle xenoliths and minerals from Eastern China
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中国东部地幔捕虏体及矿物的钙同位素组成
DOI：
10.1016/j.gca.2015.11.039
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发表时间：
2016-02
影响因子：
5
通讯作者：
Fang Huang
中科院分区：
文献类型：
--
作者：
Jin-Ting Kang;Hong-Li Zhu;Yu-Fei Liu;Fang Liu;Fei Wu;Yan-Tao Hao;Xia-Chen Zhi;Zhao-Feng Zhang;Fang Huang
本文利用地幔捕虏体中共存的单斜辉石（cpx）、正辉石（opx）和橄榄石（ol）的钙同位素数据，研究上地幔钙同位素分馏。opx的δ44/40 Ca（δ44/40 Ca（‰）=（44 Ca/40 Ca）SAMPLE/（44 Ca/40 Ca）SRM 915 a − 1）在0.95 ± 0.05‰至1.82 ± 0.01‰之间变化，cpx在0.71 ± 0.06‰至1.03 ± 0.12‰之间变化（2se）。Ol（P-15）的δ44/40 Ca为1.16 ± 0.08‰，与Op x（1.12 ± 0.09‰，2se）的δ44/40 Ca相同。Δ44/40 Caopx −cpx（Δ44/40 Caopx −cpx= δ44/40 Caopx-δ44/40 Cacpx）在-0.01 ‰ ~ 1.11‰范围内变化较大，且随opx中Ca/Mg（原子比）的减小而显著增大。这些观察结果可以反映opx组成对Ca同位素的矿物间平衡分馏的影响，与第一原理理论计算的理论预测一致（Feng等人，2014年）。当温度从1196 K升高到1267 K时，Δ44/40 Caopx − cpx减小。然而，这种矿物间同位素分馏的大小（1.12‰）与通过众所周知的矿物间同位素分馏因子与1/T2（Urey，1947）之间的相关性计算的值不一致。相反，它可以反映对Opx晶体化学的温度控制（即，Ca含量），进一步影响Δ44/40 Caopx −cpx。橄榄岩和辉石岩的δ44/40 Ca值为0.76 ± 0.06‰ ~ 1.04 ± 0.12‰（2se）。值得注意的是，橄榄岩的δ44/40 Ca与CaO呈正相关，与MgO含量呈负相关。这种相关性可以用富氧地幔端元与低δ44/40 Ca亏损地幔端元的混合来解释，表明Ca同位素是研究地幔演化的有用工具。
This study presents calcium isotope data for co-existing clinopyroxenes (cpx), orthopyroxenes (opx), and olivine (ol) in mantle xenoliths to investigate Ca isotopic fractionation in the upper mantle. δ44/40Ca (δ44/40Ca (‰) = (44Ca/40Ca)SAMPLE/(44Ca/40Ca)SRM915a− 1) in opx varies from 0.95 ± 0.05‰ to 1.82 ± 0.01‰ and cpx from 0.71 ± 0.06‰ to 1.03 ± 0.12‰ (2se). δ44/40Ca in ol (P-15) is 1.16 ± 0.08‰, identical to δ44/40Ca of the co-existing opx (1.12 ± 0.09‰, 2se). The Δ44/40Caopx−cpx(Δ44/40Caopx−cpx= δ44/40Caopx–δ44/40Cacpx) shows a large variation ranging from −0.01‰ to 1.11‰ and it dramatically increases with decreasing of Ca/Mg (atomic ratio) in opx. These observations may reflect the effect of opx composition on the inter-mineral equilibrium fractionation of Ca isotopes, consistent with the theoretical prediction by first-principles theory calculations (Feng et al., 2014). Furthermore, Δ44/40Caopx−cpxdecreases when temperature slightly increases from 1196 to 1267 K. However, the magnitude of such inter-mineral isotopic fractionation (1.12‰) is not consistent with the value calculated by the well-known correlation between inter-mineral isotope fractionation factors and 1/T2(Urey, 1947). Instead, it may reflect the temperature control on crystal chemistry of opx (i.e., Ca content), which further affects Δ44/40Caopx−cpx. The calculated δ44/40Ca of bulk peridotites and pyroxenites range from 0.76 ± 0.06‰ to 1.04 ± 0.12‰ (2se). Notably, δ44/40Ca of bulk peridotites are positively correlated with CaO and negatively with MgO content. Such correlations can be explained by mixing between a fertile mantle end-member and a depleted one with low δ44/40Ca, indicating that Ca isotopes could be a useful tool in studying mantle evolution.
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中国中东部新生代陆相玄武岩地幔源性质的地球化学约束
影响因子：
3.5
作者：
Zhang, Jun-Jun;Zhao, Zi-Fu;Wang, Yan;Zheng, Yong-Fei
通讯作者：
Zheng, Yong-Fei
影响因子：
3.9
作者：
E. Young;C. Manning;E. Schauble;A. Shahar;C. Macris;C. Lazar;M. Jordan
通讯作者：
E. Young;C. Manning;E. Schauble;A. Shahar;C. Macris;C. Lazar;M. Jordan
DOI：
--
发表时间：
2010
期刊：
--
影响因子：
--
作者：
Yigang Xu;Songyue Yu;Yong‐Fei Zheng
通讯作者：
Yigang Xu;Songyue Yu;Yong‐Fei Zheng
影响因子：
1.8
作者：
Xiao Qiong
通讯作者：
Xiao Qiong
影响因子：
5
作者：
Huang, Shichun;Farkas, Juraj;Jacobsen, Stein B.
通讯作者：
Jacobsen, Stein B.