کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4725308 | 1355977 | 2011 | 12 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Cosmogenic 3He production rates in apatite, zircon and pyroxene inferred from Bonneville flood erosional surfaces
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله

چکیده انگلیسی
3He concentrations were measured in zircon, apatite and pyroxene separates from rhyolite surfaces along the Snake River near Twin Falls, Idaho. These fluted and potholed surfaces were presumably scoured by the Bonneville outburst flood â¼17.5 ka. Several of the samples contain inherited 3He from prior exposure, reflecting the complex incision history of the Snake River canyon and suggesting earlier flood events. Each individual mineral from the remaining surfaces yielded 3He concentrations that are within error of each other. 3He produced by neutron capture on 6Li was established from shielded samples and a simple neutron production model. The remaining 3He is spallogenic and was used to calibrate the production rate of cosmogenic 3He in zircon, apatite and pyroxene by assuming minimal erosion since the Bonneville flood. In all three phases the resulting production rates are â¼7-12% lower than previous 3He production rate estimates obtained by reference to various production rates for 10Be in quartz. This disagreement is partially reconciled here by recalculating previous results with a 10Be production rate of 4.51 at gâ1 aâ1 in quartz. Adopting this revised rate brings three independent 3He production rate estimates for zircon and apatite into agreement within 5%, with grand means of 103 ± 3 at gâ1 aâ1 in zircon and 133 ± 6 at gâ1 aâ1 in apatite. The major source of uncertainty in cosmogenic 3He dating of these phases is now correction for 3He produced by neutron capture on 6Li. Calculations are presented for assessing the amount of uncertainty introduced by this correction as a function of Li concentration, cosmic-ray exposure age, and He closure age.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Quaternary Geochronology - Volume 6, Issue 1, February 2011, Pages 10-21
Journal: Quaternary Geochronology - Volume 6, Issue 1, February 2011, Pages 10-21
نویسندگان
William H. Amidon, Kenneth A. Farley,