Magnesium isotopic evidence for chemical disequilibrium among cumulus minerals in layered mafic intrusion
Magnesium isotopic evidence for chemical disequilibrium among cumulus minerals in layered mafic intrusion
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层状镁铁岩体中积云矿物之间化学不平衡的镁同位素证据
DOI：
10.1016/j.epsl.2018.01.036
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发表时间：
2018-04
影响因子：
5.3
通讯作者：
Kang Jian
中科院分区：
文献类型：
--
作者：
Chen Lie-Meng;Teng Fang-Zhen;Song Xie-Yan;Hu Rui-Zhong;Yu Song-Yue;Zhu Dan;Kang Jian
首次对白马岩体中橄榄石、单斜辉石和钛铁矿的镁同位素组成进行了研究，以确定层状镁铁质岩体中积云矿物间镁同位素分馏的大小和机制，并评价其地质意义。橄榄石和单斜辉石的Mg同位素变化有限，δ 26 Mg分别为− 0.33至+ 0.05‰和− 0.29至− 0.13‰，与地幔捕虏橄榄岩相似。相比之下，钛铁矿显示出极大的Mg同位素变化，δ 26 Mg的变化范围为− 0.50至+ 1.90‰。钛铁矿和硅酸盐矿物间镁同位素分馏的大可能反映了平衡和动力学过程。少数钛铁矿的镁同位素组成轻于共存的硅酸盐，并含有高MgO含量，没有组成分区，表明平衡分馏。这意味着，轻镁同位素组成的月球高钛玄武岩可能是由于同位素光源富集堆积钛铁矿。另一方面，大多数钛铁矿具有重Mg同位素组成，再加上高MgO浓度和化学分带，这可以定量模拟动力学Mg同位素分馏引起的钛铁矿和铁镁硅酸盐之间的亚固相线Mg-Fe交换在白马侵入体冷却。钛铁矿中Mg同位素动力学分馏的广泛发生，暗示岩浆房中火成岩矿物之间可能存在广泛的成分不平衡。因此，在研究玄武岩浆演化、岩浆房过程和岩浆型铁钛氧化物矿床成因时，必须考虑不平衡效应。
Magnesium isotopic compositions of olivine, clinopyroxene, and ilmenite from the Baima intrusion, SW China, for the first time, are investigated to constrain the magnitude and mechanisms of Mg isotope fractionation among cumulus minerals in layered mafic intrusions and to evaluate their geological implications. Olivine and clinopyroxene have limited Mg isotope variations, with δ 26 Mg ranging from− 0.33 to+ 0.05‰ and from− 0.29 to− 0.13‰, respectively, similar to those of mantle xenolithic peridotites. By contrast, ilmenites display extremely large Mg isotopic variation, with δ 26 Mg ranging from− 0.50 to+ 1.90‰. The large inter-mineral fractionations of Mg isotopes between ilmenite and silicates may reflect both equilibrium and kinetic processes. A few ilmenites have lighter Mg isotopic compositions than coexisting silicates and contain high MgO contents without compositional zoning, indicating equilibrium fractionation. The implication is that the light Mg isotopic compositions of lunar high-Ti basalts may result from an isotopically light source enriched in cumulate ilmenites. On the other hand, most ilmenites have heavy Mg isotopic compositions, coupled with high MgO concentration and chemical zoning, which can be quantitatively modeled by kinetic Mg isotope fractionations induced by subsolidus Mg–Fe exchange between ilmenite and ferromagnesian silicates during the cooling of the Baima intrusion. The extensive occurrence of kinetic Mg isotope fractionation in ilmenites implies the possibility of widespread compositional disequilibrium among igneous minerals in magma chambers. Consequently, disequilibrium effects need to be considered in studies of basaltic magma evolution, magma chamber processes, and magmatic Fe–Ti oxide ore genesis.
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DOI：
10.1007/978-94-017-9652-1_2
发表时间：
2015
期刊：
--
影响因子：
--
作者：
O. Namur;B. Abily;A. Boudreau;F. Blanchette;J. M. Bush;G. Ceuleneer;B. Charlier;C. Donaldson;J. Duchesne;Michael Denis Higgins;D. Morata;T. Nielsen;B. O’Driscoll;B. O’Driscoll;K. Pang;T. Peacock;C. Spandler;A. Toramaru;I. Veksler
通讯作者：
O. Namur;B. Abily;A. Boudreau;F. Blanchette;J. M. Bush;G. Ceuleneer;B. Charlier;C. Donaldson;J. Duchesne;Michael Denis Higgins;D. Morata;T. Nielsen;B. O’Driscoll;B. O’Driscoll;K. Pang;T. Peacock;C. Spandler;A. Toramaru;I. Veksler
DOI：
10.1007/978-94-017-9652-1_1
发表时间：
2015
期刊：
--
影响因子：
--
作者：
J. Scoates;C. Wall
通讯作者：
J. Scoates;C. Wall
影响因子：
5.8
作者：
Yigang Xu;B. He;Sun‐Lin Chung;M. Menzies;F. Frey
通讯作者：
Yigang Xu;B. He;Sun‐Lin Chung;M. Menzies;F. Frey
结晶过程中的铁同位素分馏和亚固相线再平衡：来自中国西南白马镁铁质层状岩体的约束
影响因子：
3.9
作者：
Chen Liemeng;Song Xieyan;Zhu Xiangkun;Zhang Xiaoqi;Yu Songyue;Yi Junnian
通讯作者：
Yi Junnian
影响因子：
3.8
作者：
F. Teng;Wangye Li;S. Ke;Wei Yang;Sheng‐Ao Liu;F. Sedaghatpour;Shui‐Jiong Wang;Kang-Jun Huang-
通讯作者：
F. Teng;Wangye Li;S. Ke;Wei Yang;Sheng‐Ao Liu;F. Sedaghatpour;Shui‐Jiong Wang;Kang-Jun Huang-