Delano J W
Department of Earth and Atmospheric Sciences, New York Center for Studies on the Origins of Life, University at Albany (SUNY), Albany, NY 12222-0001, USA.
Orig Life Evol Biosph. 2001 Aug-Oct;31(4-5):311-41. doi: 10.1023/a:1011895600380.
The history of the oxidation state in the Earth's mantle has been constrained using (a) the whole-rock abundances of Cr and V in ancient volcanics, and (b) the composition of Cr-rich spinels in ancient volcanics. Results indicate that the Earth's mantle has been at-or-near its current oxidation state (+/- 0.5 log-unit fO2) since at least 3600 Ma, and probably since at least 3960 Ma. Volatiles released into the Earth's atmosphere by high-temperature (T > or = 1300 K) volcanism during this time have been dominated by H2O, CO2, and SO2. This blend of volatiles is known to provide smaller yields of prebiotic, organic molecules by atmospheric and surface processes than gas mixtures containing higher concentrations of reduced species such as H2, CO, and H2S (e.g., Miller, 1998; Zolotov and Shock, 2000). The results discussed in this article independently support the conclusion of Canil (1997, 1999). If the atmosphere was reducing (e.g., CH4, H2, H2S, NH3, CO) at any time during the last approximately 3900 Ma, high-temperature volcanic outgassing was not the cause of it.
利用（a）古代火山岩中铬（Cr）和钒（V）的全岩丰度，以及（b）古代火山岩中富铬尖晶石的成分，对地球地幔中氧化态的历史进行了限制。结果表明，至少自36亿年前以来，地球地幔一直处于或接近其当前的氧化态（fO2的±0.5对数单位），可能至少自39.6亿年前以来就是如此。在此期间，高温（T≥1300K）火山活动释放到地球大气中的挥发性物质主要是水（H2O）、二氧化碳（CO2）和二氧化硫（SO2）。众所周知，与含有较高浓度还原物种（如氢气（H2）、一氧化碳（CO）和硫化氢（H2S））的气体混合物相比，这种挥发性物质的混合物通过大气和表面过程产生的益生元有机分子产量较低（例如，米勒，1998年；佐洛托夫和肖克，2000年）。本文讨论的结果独立支持了卡尼尔（1997年、1999年）的结论。如果在过去大约39亿年中的任何时候大气是还原性的（例如，甲烷（CH4）、氢气（H2）、硫化氢（H2S）、氨气（NH3）、一氧化碳（CO）），那么高温火山排气并不是其原因。
