کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8910972 | 1637935 | 2018 | 39 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Diffusion-driven magnesium and iron isotope fractionation at a gabbro-granite boundary
ترجمه فارسی عنوان
تقسیم بندی ایزوتوپی منیزیم و آهن در یک مرز گابرو گرانیت
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
چکیده انگلیسی
Significant magnesium and iron isotope fractionations were observed in an adjacent gabbro and granite profile from the Dabie Orogen, China. Chilled margin and granitic veins at the gabbro side and gabbro xenoliths in the granite indicate the two intrusions were emplaced simultaneously. The δ26Mg decreases from â0.28â¯Â±â¯0.04â° to â0.63â¯Â±â¯0.08â° and δ56Fe increases from â0.07â¯Â±â¯0.03â° toâ¯+0.25â¯Â±â¯0.03â° along a â¼16â¯cm traverse from the contact to the granite. Concentrations of major elements such as Al, Na, Ti and most trace elements also systematically change with distance to the contact. All the observations suggest that weathering, magma mixing, fluid exsolution, fractional crystallization and thermal diffusion are not the major processes responsible for the observed elemental and isotopic variations. Rather, the negatively correlated Mg and Fe isotopic compositions as well as co-variations of Mg and Fe isotopes with Mg# reflect Mg-Fe inter-diffusion driven isotope fractionation, with Mg diffusing from the chilled gabbro into the granitic melt and Fe oppositely. The diffusion modeling yields a characteristic diffusive transport distance of â¼6â¯cm. Consequently, the diffusion duration, during which the granite may have maintained a molten state, can be constrained to â¼2â¯My. The cooling rate of the granite is calculated to be 52-107â¯Â°C/My. Our study suggests diffusion profiles can be a powerful geospeedometry. The observed isotope fractionations also indicate that Mg-Fe inter-diffusion can produce large stable isotope fractionations at least on a decimeter scale, with implications for Mg and Fe isotope study of mantle xenoliths, mafic dikes, and inter-bedded lavas.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geochimica et Cosmochimica Acta - Volume 222, 1 February 2018, Pages 671-684
Journal: Geochimica et Cosmochimica Acta - Volume 222, 1 February 2018, Pages 671-684
نویسندگان
Hongjie Wu, Yongsheng He, Fang-Zhen Teng, Shan Ke, Zhenhui Hou, Shuguang Li,