The preservation state of organic matter in meteorites from Antarctica
The preservation state of organic matter in meteorites from Antarctica
复制标题
南极陨石中有机质的保存状况
DOI：
10.1111/j.1945-5100.2004.tb00116.x
复制
发表时间：
2004
影响因子：
2.2
通讯作者：
Iain Gilmour
中科院分区：
文献类型：
--
作者：
M. Sephton;Philip A. Bland;C. Pillinger;Iain Gilmour
翻译后摘要-大量的陨石从南极洲的回收大大增加了大量的外星物质可用于太阳系起源和演化的实验室研究。然而，南极陨石的巨大年龄引起了人们的关注，即大量的陆地风化已经破坏了它们的前地球记录。在碳质泥岩中发现的有机物质是最容易受到陆地作用改变的成分之一。为了评估南极风化对非南极和南极有机物的影响，对一些CM陨石进行了分析。穆斯堡尔光谱已被用于确定前-陆生和陆生氧化水平，而热解-气相色谱-质谱法被用于确定任何有机物质的构成。在非南极大陆的含铁矿物中氧化水平的增加可能是对母体水蚀变量增加的反应。母体加工似乎也从有机材料中除去醚键，从其组成单元中除去烷基侧链。南极陨石中的铁通常比非南极陨石中的铁氧化得更多，反映了陆地风化。南极洲风化的南极有机质似乎以类似的方式进行母体水蚀变，只是增强了在非南极数据集中观察到的有机反应。在解释来自这些陨石的数据时，应考虑到南极陨石中的地前过程记录的退化。
Abstract— The recovery of large numbers of meteorites from Antarctica has dramatically increased the amount of extraterrestrial material available for laboratory studies of solar system origin and evolution. Yet, the great age of Antarctic meteorites raises the concern that significant amounts of terrestrial weathering has corrupted their pre‐terrestrial record. Organic matter found in carbonaceous chondrites is one of the components most susceptible to alteration by terrestrial processes. To assess the effects of Antarctic weathering on both non‐Antarctic and Antarctic chondritic organic matter, a number of CM chondrites have been analyzed. Mössbauer spectroscopy has been used to ascertain pre‐terrestrial and terrestrial oxidation levels, while pyrolysis‐gas chromatography‐mass spectrometry was used to determine the constitution of any organic matter present. Increased oxidation levels for iron bearing minerals within the non‐Antarctic chondrites are likely to be a response to increased amounts of parent body aqueous alteration. Parent body processing also appears to remove ether bonds from organic material and alkyl side chains from its constituent units. The iron in Antarctic chondrites is generally more oxidized than that in their non‐Antarctic counterparts, reflecting terrestrial weathering. Antarctic weathering of chondritic organic matter appears to proceed in a similar way to parent body aqueous alteration and simply enhances the organic responses observed in the non‐Antarctic data set. Degradation of the record of preterrestrial processes in Antarctic chondrites should be taken into account when interpreting data from these meteorites.