Meteorite ablation products and their contribution to the atmospheres of terrestrial planets: An experimental study using pyrolysis-FTIR
Meteorite ablation products and their contribution to the atmospheres of terrestrial planets: An experimental study using pyrolysis-FTIR
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DOI：
10.1016/j.gca.2009.03.006
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发表时间：
2009-06
影响因子：
5
通讯作者：
R. Court;M. Sephton
中科院分区：
文献类型：
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作者：
R. Court;M. Sephton
我们使用最近开发的定量热解-傅里叶变换红外光谱法来测量一系列碳质球粒陨石在 250°C 解吸和 1000°C 气化步骤期间水和二氧化碳的产生。气化过程中较高的水和二氧化碳产量与陨石有关，据信陨石在其小行星母体上经历了更多的水蚀变化（即岩相学类型1>类型2>类型3的气体产量）。挥发性产量很可能反映了水合矿物相和部分氧化有机物的数量。在陨石的气化产物中没有检测到甲烷，根据所采用的热解-傅里叶变换红外光谱技术的灵敏度，可以计算出其产量的上限约为 100ppm。当与地球历史上宇宙尘埃的坠落速率一起考虑时，这些数据可用于评估尘埃进入大气层时热烧蚀过程中挥发物的产生，并估计它们对类地行星大气层和水圈的贡献。从长远来看，这种性质对地球挥发性库存的贡献似乎很小，尽管根据计算，在 3.8-4.0Ga 的后期重轰炸之前和期间，生产率要高得多。此外，碳质球粒陨石材料的烧蚀似乎并不是火星大气甲烷预算的合理来源。
We have used a recently developed quantitative pyrolysis-Fourier transform infrared spectroscopy method to measure the production of water and carbon dioxide during 250°C desorption and 1000°C gasification steps for a range of carbonaceous chondrites. Greater yields of water and carbon dioxide during gasification are associated with meteorites believed to have experienced more aqueous alteration on their asteroid parent body (i.e. gas yields for petrographic type 1>type 2>type 3). Volatile yields most likely reflect quantities of hydrated mineral phases and partially oxidised organic matter. Methane was not detected in the gasification products of the meteorites, allowing an upper limit on its production of around 100ppm to be calculated based on the sensitivity of the pyrolysis-Fourier transform infrared spectroscopy technique employed. When considered alongside rates of infall of cosmic dust throughout Earth history, the data can be used to evaluate the production of volatiles during the thermal ablation of dust upon atmospheric entry, and to estimate their contribution to a terrestrial planet’s atmosphere and hydrosphere. Over the long term, it appears that contributions of this nature to the Earth’s volatile inventory are small, although production rates are calculated to have been substantially higher before and during the Late Heavy Bombardment of 3.8–4.0Ga. Moreover, ablation of carbonaceous chondritic material does not appear to be a plausible source of the atmospheric methane budget of Mars.