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.

中文翻译：

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0.25 Ga盐矿保留了宜居条件和古代脂质的特征。

研究了一个约2.5亿年历史的二叠纪蒸发矿床的多边形特征的地质和有机含量，以检验它们可以保留古代宜居条件和生物活动特征的假设。蒸发岩的研究是英国Boulby矿的MIne模拟研究（MINAR）项目的一部分。与多边形内部相比，多边形的边缘具有更高的粘土含量，并且包含更高含量的矿物，例如石英和微斜纹岩以及伊利石和绿泥石等粘土，这表明边缘是风化产物积累的首选位置在他们的形成。矿物含量及其锶同位素比表明，该物质来自二叠纪Zechstein海边界的大陆风化作用。多边形的边缘包含平均δ的材质¹³ C和δ ^15个分别的N个值-20.8和5.3。从多边形的内部和边缘提取脂质，包括烷烃和hop烷，推断它们代表形成时夹带在蒸发物中的有机物质。长链烷烃（C ₂₀ –C ₃₅）缺乏碳优先性，C ₂₃ –C _29的丰度低烷和缺乏海洋，蒸发或热成熟度指标表明，脂质生物标志物至少部分可能源自大陆来源，并且自沉积以来未经历过明显的热成熟。使用弱酸的脂质提取所显示的脂质比不含酸的脂质要多得多，这可能表明包囊不是布尔比盐中唯一发生的保存机制。这些数据证明了古代蒸发岩及其多边形保存有关当地地质条件，古代可居住性和生命证据的信息的潜力。数据表明，类似的火星蒸发沉积物是未来生命探测任务和古代火星可居住性研究的良好目标。