کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4700804 1637730 2008 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Zircon oxygen isotopic constraint on the sources of late Mesozoic A-type granites in eastern China
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
Zircon oxygen isotopic constraint on the sources of late Mesozoic A-type granites in eastern China
چکیده انگلیسی

A-type granites are usually derived from partial melting of the lower crust and/or the upper mantle within extensional settings, but their exact sources for specific plutons are required to unravel. A systematic laser fluorination analysis of oxygen isotopes was carried out for five well-documented late Mesozoic A-type granites in eastern China. Zircon from 41 samples was separated and 109 aliquots of fresh zircon were analyzed along with whole-rock powder and quartz from the same samples. Hydrothermally altered whole-rock samples show scattered δ18O values of − 2.3 to 7.4‰, with a total variation up to 9.7‰. In contrast, zircon δ18O values vary only from 3.1 to 5.4‰, with a range of 2.3‰. Most available zircon δ18O values of A-type granites are lower than normal mantle zircon values of 5.3 ± 0.6‰ (2SD), and high-temperature equilibrium fractionations are well preserved between quartz and zircon in most cases. The above lines of evidence suggest that the low δ18O zircons in A-type granites were crystallized from low δ18O magmas. Because low δ18O magmas cannot be derived entirely from the mantle, reworking and/or recycling of crustal igneous rocks are involved for their petrogenesis. The low δ18O zircons in this study thus offer evidence for a dominantly crustal origin of the late Mesozoic A-type granites in eastern China.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Geology - Volume 250, Issues 1–4, 1 May 2008, Pages 1–15
نویسندگان
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