Metasedimentary rocks from Isua, West Greenland (> 3,700 million years old) contain carbonaceous compounds, compatible with a biogenic origin (Hassenkam, Andersson, Dalby, Mackenzie, & Rosing, 2017; Ohtomo, Kakegawa, Ishida, Nagase, & Rosing, 2014; Rosing, 1999). The metamorphic mineral assemblage with garnet and quartz intergrowths contains layers of carbonaceous inclusions contiguous with carbon‐rich sedimentary beds in the host rock. Previous studies (Hassenkam et al., 2017; Ohtomo et al., 2014; Rosing, 1999) on Isua rocks focused on testing the biogenic origin of the carbonaceous material, but here we searched for evidence which could provide new insights into the nature of the life that generated this carbonaceous material. We studied material trapped in inclusions armoured within quartz grains inside garnet porphyroblasts by non‐destructive ptychographic X‐ray nanotomography (PXCT). The 3D electron density maps generated by PXCT were correlated with maps from X‐ray fluorescence tomography and micro‐Raman spectroscopy. We found that the material trapped inside inclusions in the quartz grains consist of disordered carbon material encasing domains of iron‐rich carbonaceous material. These results corroborate earlier claims (Hassenkam et al., 2017; Ohtomo et al., 2014; Rosing, 1999) for biogenic origins and are compatible with relics of metamorphosed biological material originally containing high iron/carbon ratios, comparable to ratios found in most extant organisms. These iron‐rich domains represent the oldest evidence for organic iron complexes in the geologic record and are consistent with Fe‐isotopic evidence for metabolic iron fractionation in > 3,700 Ma Isua banded iron formation (Czaja et al., 2013; Whitehouse & Fedo, 2007).

中文翻译：

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eoarchean铁代谢的直接证据？

来自西格陵兰岛伊苏阿的沉积沉积岩（> 37亿年前）含有与生物成因相容的碳质化合物（Hassenkam，Andersson，Dalby，Mackenzie和Rosing，2017年; Ohtomo，Kakegawa，石田，长濑和Rosing，2014年; Rosing，1999）。带有石榴石和石英共生体的变质矿物组合体包含碳质包裹体层，这些碳质包裹体与宿主岩体中富含碳的沉积层相邻。以前在Isua岩石上进行的研究（Hassenkam等，2017; Ohtomo等，2014; Rosing，1999）专注于测试碳质材料的生物成因，但在这里我们搜索的证据可以提供有关碳素性质的新见解。产生这种碳质物质的生命。我们通过非破坏性谱图X射线纳米断层扫描（PXCT）研究了石榴石成卟啉细胞内石英颗粒内装甲的包裹体中捕获的物质。PXCT生成的3D电子密度图与X射线荧光层析成像和显微拉曼光谱图相关联。我们发现，被困在石英晶粒内夹杂物内部的材料由无序的碳材料包裹着富含铁的碳质材料的区域组成。这些结果证实了较早的关于生物成因的主张（Hassenkam等，2017; Ohtomo等，2014; Rosing，1999），并且与最初含有高铁/碳比的变态生物材料的遗迹兼容，可与大多数现存的生物。