Bender Michael L, Barnett Bruce, Dreyfus Gabrielle, Jouzel Jean, Porcelli Don
Department of Geosciences, Princeton University, Princeton, NJ 08544, USA.
Proc Natl Acad Sci U S A. 2008 Jun 17;105(24):8232-7. doi: 10.1073/pnas.0711679105. Epub 2008 Jun 11.
Knowledge of the outgassing history of radiogenic (40)Ar, derived over geologic time from the radioactive decay of (40)K, contributes to our understanding of the geodynamic history of the planet and the origin of volatiles on Earth's surface. The (40)Ar inventory of the atmosphere equals total (40)Ar outgassing during Earth history. Here, we report the current rate of (40)Ar outgassing, accessed by measuring the Ar isotope composition of trapped gases in samples of the Vostok and Dome C deep ice cores dating back to almost 800 ka. The modern outgassing rate (1.1 +/- 0.1 x 10(8) mol/yr) is in the range of values expected by summing outgassing from the continental crust and the upper mantle, as estimated from simple calculations and models. The measured outgassing rate is also of interest because it allows dating of air trapped in ancient ice core samples of unknown age, although uncertainties are large (+/-180 kyr for a single sample or +/-11% of the calculated age, whichever is greater).
了解放射性（40）Ar的脱气历史，它是在地质时期由（40）K的放射性衰变产生的，有助于我们理解地球的地球动力学历史以及地球表面挥发物的起源。大气中的（40）Ar存量等于地球历史期间的总（40）Ar脱气量。在此，我们报告了当前的（40）Ar脱气速率，通过测量来自沃斯托克和 Dome C 深冰芯样本中捕获气体的Ar同位素组成来确定，这些冰芯样本可追溯到近80万年。现代脱气速率（1.1 +/- 0.1 x 10（8）mol/年）处于通过简单计算和模型估算的大陆地壳和上地幔脱气总量预期值范围内。测量的脱气速率也很有意义，因为它可以对年龄未知的古代冰芯样本中捕获的空气进行测年，尽管不确定性很大（单个样本为 +/-18万年或计算年龄的 +/-11%，取较大值）。
