کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9529006 | 1637785 | 2005 | 20 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Zircon U-Pb chemical abrasion (“CA-TIMS”) method: Combined annealing and multi-step partial dissolution analysis for improved precision and accuracy of zircon ages
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
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
A long-standing goal in high-precision and high-accuracy U-Pb zircon geochronology is the total elimination of discordance caused by Pb loss. In theory, this is fairly straightforward, but in reality it has proven extremely difficult to attain (or even demonstrate attainment of) this goal. However, a new method, “CA (Chemical Abrasion)-TIMS”, is capable of completely removing zircon domains that have lost Pb, and then analyzing residual, perfectly closed-system zircon. CA-TIMS uses high-temperature treatment (in the range of 800-1100 °C for 48 h) to anneal zircon lattice radiation damage from natural alpha, alpha recoil, and spontaneous fission processes; this annealing eliminates elemental and isotopic leaching effects that have limited earlier efforts at chemical “leaching” or multi-step “step-wise dissolution” or “partial dissolution analysis (PDA)”. The annealed zircons are then subjected to a series of partial dissolution steps at progressively higher temperatures. These steps initially remove (usually outer) zircon zones with high U + Th concentrations. These earliest partial dissolution steps are invariably slightly to strongly discordant, due to Pb loss. Later steps sample progressively lower U + Th zircon domains. In zircon samples that lack inheritance, these later steps sample zircon domains that are completely free from Pb loss, defining 206Pb*/238U plateau ages with precisions (and accuracies, subject to decay constant and tracer calibration accuracies) better than 0.1%.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Geology - Volume 220, Issues 1â2, 12 July 2005, Pages 47-66
Journal: Chemical Geology - Volume 220, Issues 1â2, 12 July 2005, Pages 47-66
نویسندگان
James M. Mattinson,