کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5784035 | 1638630 | 2017 | 40 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Iron isotope fractionation during crustal anatexis: Constraints from migmatites from the Dabie orogen, Central China
ترجمه فارسی عنوان
تجزیه ایزوتوپ آهن در طول آناتکسی پوسته: محدودیت های مگماتیت از دبی اگنژن، چین مرکزی
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
چکیده انگلیسی
Iron (Fe) isotope fractionation could occur during crustal melting, which may contribute to the isotopic variations of granites. Our current knowledge on Fe isotope fractionation during crustal melting remains rare. Thirteen leucosomes, 9 melanosomes and 1 amphibolitic schollen in 11 migmatites from the Dabie orogen, Central China were measured to investigate Fe isotope fractionation during crustal anatexis. The melanosomes and amphibolitic schollen yield δ56Fe values from 0.018 ± 0.031â° to 0.152 ± 0.027â° with an average of 0.106â°. The leucosomes have δ56Fe values from 0.107 ± 0.035â° to 0.512 ± 0.028â°, variably higher than their coexisting melanosomes by 0.00 ~ 0.36â°. The δ56Fe of leucosomes and melanosomes, as well as apparent isotope fractionation (Î56FeL-M) between them, do not correlate with the abundance of crystalline carbonate, loss on ignition, and Th/U, indicating the insignificant effect of fluid components. High δ56Fe values of three leucosomes (â¥Â 0.34â°), giving large Î56FeL-M from 0.22 to 0.36â°, were likely produced by feldspar accumulation, evidenced by their high Eu*, low FeOt/Al2O3 and high plagioclase abundance up to 50 vol%. Capture of peritectic amphiboles in another leucosome may explain its low Î56FeL-M ~ 0â°. After screening out these samples, 7 leucosome - melanosome pairs yield identical Î56FeL-M averaging 0.093 ± 0.056â° (2SD, N = 7) within analytical uncertainties. No correlation between Î56FeL-M and Mg#, FeOt/Al2O3 or TiO2/FeOt rules out the possibility that the fractionation observed here is produced by fractional crystallization and/or sub-solidus isotope re-equilibrium between leucosomes and melanosomes. Therefore, we suggest these consistent Î56FeL-M should record equilibrium Fe isotope fractionation during crustal anatexis producing these migmatites. The leucosomes and melanosomes have comparable Fe3 +/ΣFe ~ 0.40, and Î56FeL-M approximates 0.07â° at Fe3+/ΣFeleucosomeFe3+/ΣFemenalosome= 1. Fe isotope fractionation during crustal anatexis revealed here thus is not dominantly controlled by distribution of Fe3 + and Fe2 +, but by the difference in coordination number of iron between granitic melts and residual mafic minerals. The observation here argues that Fe isotope fractionation during crustal partial melting should also contribute to the previously revealed δ56Fe variation in high silica granitic rocks.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Lithos - Volumes 284â285, July 2017, Pages 171-179
Journal: Lithos - Volumes 284â285, July 2017, Pages 171-179
نویسندگان
Li-Juan Xu, Yongsheng He, Shui-Jiong Wang, Hongjie Wu, Shuguang Li,