0.25 Ga Salt Deposits Preserve Signatures of Habitable Conditions and Ancient Lipids.
0.25 Ga Salt Deposits Preserve Signatures of Habitable Conditions and Ancient Lipids.
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DOI：
10.1089/ast.2019.2053
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发表时间：
2020-04
期刊：
影响因子：
4.2
通讯作者：
C. Cockell;M. Wilhelm;S. Perl;J. Wadsworth;S. Payler;S. McMahon;S. Paling;Tom Edwards
中科院分区：
文献类型：
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作者：
C. Cockell;M. Wilhelm;S. Perl;J. Wadsworth;S. Payler;S. McMahon;S. Paling;Tom Edwards
对一个2.5亿年前的二叠纪榴辉岩存款中的多晶特征进行了研究，以确定其地质和有机含量，以检验它们可以保留古代居住条件和生物活动的特征的假设。在英国博尔比矿进行的矿物模拟研究（MINAR）项目的一部分，对钾长岩进行了调查。多边形的边缘有较高的粘土含量，并含有较高丰度的矿物，如石英和微斜长石，粘土，如伊利石和粘土，与多边形的内部相比，这表明边缘的风化产物在其形成过程中积累的首选位置。矿物含量和锶同位素比值表明，该物质来自二叠纪Zechstein海边缘的大陆风化。多边形的边缘含有δ 13 C和δ 15 N平均值分别为-20.8和5.3的物质。从多边形的内部和边缘提取了脂质，包括烷烃和藿烷，推断它们代表了形成时夹带在陨石中的有机物质。缺乏碳偏好的长链烷烃（C20-C35）的存在，C23-C29藿烷的低丰度，以及缺乏海洋，碳酸盐岩，或热成熟度指标表明，脂质生物标志物，至少部分，可能来自大陆的来源，并没有经历过显着的热成熟，因为沉积。使用弱酸的脂质提取揭示了比那些没有酸的脂质显著更多的脂质，这可能表明包封不是在Boulby盐中发生的唯一类型的保存机制。这些数据表明，古代的珊瑚礁及其多边形保存当地地质条件，古代可居住性和生命证据的信息的潜力。这些数据表明，类似的火星陨石沉积物是未来生命探测任务和古代火星可居住性调查的良好目标。
Polygonal features in a ∼250 million-year-old Permian evaporitic deposit were investigated for their geological and organic content to test the hypothesis that they could preserve the signature of ancient habitable conditions and biological activity. Investigations on evaporitic rock were carried out as part of the MIne Analog Research (MINAR) project at Boulby Mine, the United Kingdom. The edges of the polygons have a higher clay content and contain higher abundances of minerals such as quartz and microcline, and clays such as illite and chlorite, compared with the interior of polygons, suggesting that the edges were preferred locations for the accumulation of weathering products during their formation. The mineral content and its strontium isotope ratio suggest that the material is from continental weathering at the borders of the Permian Zechstein Sea. The edges of the polygons contain material with mean δ13C and δ15N values of -20.8 and 5.3, respectively. Lipids, including alkanes and hopanes, were extracted from the interior and edges of the polygons, which are inferred to represent organic material entrained in the evaporites when they were formed. The presence of long-chain alkanes (C20-C35) that lack a carbon preference, low abundances of C23-C29 hopanes, and lack of marine, evaporitic, or thermal maturity indicators show that lipid biomarkers were, at least in part, potentially derived from a continental source and have not undergone significant thermal maturation since deposition. Lipid extractions using weak acids revealed significantly more lipids than those without acid, potentially indicating that encapsulation was not the only type of preservation mechanism occurring in Boulby salts. These data demonstrate the potential for ancient evaporites and their polygons to preserve information on local geological conditions, ancient habitability, and evidence of life. The data show that analogous martian evaporitic deposits are good targets for future life detection missions and the investigation of ancient martian habitability.