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  4. 岩石圈演化国家重点实验室
The Chromite Crisis in the Evolution of Continental Magmas and the Initial High delta Mg-26 Reservoir

文献类型：期刊论文

作者Xiao, Yan6; Yuan, Meng6,7; Su, Ben-Xun1,7; Chen, Chen2; Bai, Yang5; Ke, Shan3; Sun, Yang4; Robinson, Paul T.6
刊名JOURNAL OF PETROLOGY
出版日期2023-04-01
卷号64期号:4页码:18
ISSN号0022-3530
关键词intra-continental magmatism isotope fractionation chromite segregation fractional crystallization magnesium isotopes
DOI10.1093/petrology/egad019
英文摘要Fractional crystallization of Fe-Ti oxides can induce detectable Mg isotopic changes during late-stage basalt differentiation. Because chromite and olivine are early crystallizing phases during basaltic melt differentiation, the effect of chromite crystallization on the fractionation of Mg isotopes during early-stage basalt differentiation is still poorly understood. Here, we examine the possibility of chromite induced Mg isotope fractionation with a Mg isotopic study of chromite-olivine pairs in dunites and chromitites collected from major types of basaltic intrusive rock suites formed by fractional crystallization in different tectonic settings. The chromite delta Mg-26 (= [(Mg-26/Mg-24)(sample) / (Mg-26/Mg-24)(DSM3)-1] x 1000) values range from -0.19 parts per thousand to 0.30 parts per thousand in the Luobusa ophiolite, -0.09 parts per thousand to 0.78 parts per thousand in the Kizildag ophiolite, -0.04 to 0.42 parts per thousand in the Gaositai Alaskan-type complex, similar to those previously reported from the Stillwater layered intrusion (-0.05 to 0.84 parts per thousand; ). They are significantly higher than those of coexisting olivine (delta Mg-26 = -0.48 to -0.10 parts per thousand). The Delta Mg-26(Chr-Ol) (= delta Mg-26(Chr) - delta Mg-26(Ol)) values in the rock suites investigated here fall largely between equilibrium fractionation lines of spinel-olivine pairs and magnesioferrite-olivine pairs, indicating equilibrium Mg isotopic fractionation. Furthermore, the Delta Mg-26(Chr-Ol) values increase with decreasing Cr content of chromite in the dunites and chromitites, showing that high Mg-26 has a greater affinity to Al-rich chromite than Cr-rich chromite. Fractional crystallization of such isotopically high chromite is expected to progressively lower the Mg isotope values of the in the remaining magma. Furthermore, continental basaltic magmas typically experience early crystallization of olivine and Al-rich chromite. Their delta Mg-26 values correlate positively with MgO (FeO, Cr,) and CaO/Al2O3 ratios and negatively with total alkali contents (Na2O + K2O). This indicates that detectable Mg isotopic fractionation occurred in intra-continental basalt magmas, probably by fractional crystallization of olivine and chromite. The observed low-delta Mg-26 intra-continental basalts can be accurately modeled by olivine + chromite fractionation with fractionation factors (Delta Mg-26(Chr-Melt)) of 0.20 parts per thousand, 0.60 parts per thousand, and 1.18 parts per thousand as observed in the chromitites investigated during this study. Therefore, the early-stage basaltic melt differentiation involving separation of olivine and chromite may induce resolvable Mg isotopic fractionation, and the delta Mg-26 values of continental basalts should be used with caution in petrogenetic studies.
WOS关键词MAGNESIUM ISOTOPE FRACTIONATION ; CHINA CRATON IMPLICATIONS ; MELT-ROCK INTERACTION ; DEEP CARBON-CYCLE ; PODIFORM CHROMITITES ; LUOBUSA OPHIOLITE ; KIZILDAG OPHIOLITE ; OXIDATION-STATE ; TRANSITION ZONE ; MG ISOTOPES
资助项目Second Tibetan Plateau Scientific Expedition and Research Program (STEP)[2019QZKK0801] ; National Natural Science Foundation of China[41973012] ; National Natural Science Foundation of China[91755205] ; National Natural Science Foundation of China[41772055] ; Ministry of Science and Technology National Key R&D Program of China[2022YFC2903501]
WOS研究方向Geochemistry & Geophysics
语种英语
出版者OXFORD UNIV PRESS
WOS记录号WOS:001008020400001
资助机构Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; Ministry of Science and Technology National Key R&D Program of China ; Ministry of Science and Technology National Key R&D Program of China ; Ministry of Science and Technology National Key R&D Program of China ; Ministry of Science and Technology National Key R&D Program of China ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; Ministry of Science and Technology National Key R&D Program of China ; Ministry of Science and Technology National Key R&D Program of China ; Ministry of Science and Technology National Key R&D Program of China ; Ministry of Science and Technology National Key R&D Program of China ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; Ministry of Science and Technology National Key R&D Program of China ; Ministry of Science and Technology National Key R&D Program of China ; Ministry of Science and Technology National Key R&D Program of China ; Ministry of Science and Technology National Key R&D Program of China ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; Ministry of Science and Technology National Key R&D Program of China ; Ministry of Science and Technology National Key R&D Program of China ; Ministry of Science and Technology National Key R&D Program of China ; Ministry of Science and Technology National Key R&D Program of China
源URL[http://ir.iggcas.ac.cn/handle/132A11/111257]  
专题地质与地球物理研究所_岩石圈演化国家重点实验室
地质与地球物理研究所_中国科学院矿产资源研究重点实验室
通讯作者Xiao, Yan
作者单位1.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Mineral Resources, Beijing 100029, Peoples R China
2.Chinese Acad Sci, Guangzhou Inst Geochem, Key Lab Mineral & Metallogeny, Guangzhou 510640, Peoples R China
3.China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Beijing 100083, Peoples R China
4.Southern Univ Sci & Technol, Dept Earth & Space Sci, Shenzhen 518055, Guangdong, Peoples R China
5.Taiyuan Univ Technol, Coll Min Engn, Taiyuan 030024, Peoples R China
6.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
7.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
推荐引用方式
GB/T 7714		 Xiao, Yan,Yuan, Meng,Su, Ben-Xun,et al. The Chromite Crisis in the Evolution of Continental Magmas and the Initial High delta Mg-26 Reservoir[J]. JOURNAL OF PETROLOGY,2023,64(4):18.
APA Xiao, Yan.,Yuan, Meng.,Su, Ben-Xun.,Chen, Chen.,Bai, Yang.,...&Robinson, Paul T..(2023).The Chromite Crisis in the Evolution of Continental Magmas and the Initial High delta Mg-26 Reservoir.JOURNAL OF PETROLOGY,64(4),18.
MLA Xiao, Yan,et al."The Chromite Crisis in the Evolution of Continental Magmas and the Initial High delta Mg-26 Reservoir".JOURNAL OF PETROLOGY 64.4(2023):18.

入库方式： OAI收割

来源：地质与地球物理研究所

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