Pyrite and Organic Compounds Coexisting in Intrusive Mafic Xenoliths (Hyblean Plateau, Sicily): Implications for Subsurface Abiogenesis.

IF 1.9 4区物理与天体物理 Q2 BIOLOGY

Origins of Life and Evolution of Biospheres Pub Date : 2019-06-01 Epub Date: 2019-07-13 DOI:10.1007/s11084-019-09581-w

Vittorio Scribano, Sergei K Simakov, Claudio Finocchiaro, Alessandra Correale, Salvatore Scirè

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引用次数: 3

Abstract

Pyrite and organic matter closely coexist in some hydrothermally-altered gabbroic xenoliths from the Hyblean Plateau, Sicily. The representative sample consists of plagioclase, Fe-oxides, clinopyroxene, pyrite and minor amounts of many other minerals. Plagioclase displays incipient albitization, clinopyroxene is deeply corroded. Pyrite grains are widely replaced by spongy-textured magnetite, which locally hosts Ca-(and Fe-)sulfate micrograins and blebs of condensed organic matter. Whole-rock trace element distribution evidences that incompatible elements, particularly the fluid-mobile Ba, U and Pb, are significantly enriched with respect to N-MORB values. The mineralogical and geochemical characteristics of the sample, and its U-Pb zircon age of 216.9 ± 6.7 MA, conform to the xenolith-based viewpoint that the unexposed Hyblean basement is a relict of the Ionian Tethys lithospheric domain, mostly consisting of abyssal-type serpentinized peridotites with small gabbroic intrusions. Circulating hydrothermal fluids there favored the formation of hydrocarbons trough Fischer-Tropsch-type organic synthesis, giving also rise to sulfidization episodes. Subsequent variations in temperature and redox conditions of the system induced partial de-sulfidization, Fe-oxides precipitation and sulfate-forming reactions, also promoting poly-condensation and aromatization of the already-formed hydrocarbons. Here we show organic matter adhering to a crystal face of a microscopic pyrite grain. Pyrite surfaces, as abiotic analogues of enzymes, can adsorb and concentrate organic molecules, also acting as catalysts for a broad range of proto-biochemical reactions. The present data therefore may support established abiogenesis models suggesting that pyrite surfaces carried out primitive metabolic cycles in suitable environments of the early Earth, such as endolithic recesses in mafic rocks permeated by hydrothermal fluids.

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黄铁矿和有机化合物共存于侵入岩岩浆异岩石中（西西里岛海布伦高原）：对地表下生物生成的影响。

黄铁矿和有机物密切共存于西西里海布伦高原的一些热液蚀变辉长岩异长岩中。代表性样本由斜长石、铁氧化物、霞石、黄铁矿和少量其他矿物组成。斜长石初现白化现象，霞石被严重腐蚀。黄铁矿晶粒广泛被海绵状质地的磁铁矿所取代，其中局部含有硫酸钙（和硫酸铁）微晶粒和凝结有机物斑点。整个岩石的微量元素分布证明，不相容元素，特别是流体流动的 Ba、U 和 Pb，与 N-MORB 值相比明显富集。该样品的矿物学和地球化学特征及其 216.9 ± 6.7 MA 的 U-Pb 锆石年龄符合基于异长岩的观点，即未出露的海布伦基底是爱奥尼亚特提斯岩石圈域的遗迹，主要由深海型蛇纹岩化橄榄岩和小型辉长岩侵入体组成。那里的热液循环有利于通过费托型有机合成形成碳氢化合物，同时也引起了硫化现象。随后系统温度和氧化还原条件的变化引起了部分脱硫、铁氧化物沉淀和硫酸盐形成反应，也促进了已形成的碳氢化合物的缩聚和芳香化。在这里，我们展示了附着在微观黄铁矿晶粒晶面上的有机物。黄铁矿表面作为酶的非生物类似物，可以吸附和浓缩有机分子，同时也是一系列原生化反应的催化剂。因此，目前的数据可能支持既定的生物起源模型，即黄铁矿表面在地球早期的适宜环境中，如热液渗透的岩浆岩内凹处，进行原始的新陈代谢循环。

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来源期刊

Origins of Life and Evolution of Biospheres 生物-生物学

CiteScore

3.20

自引率

15.00%

发文量

审稿时长

>12 weeks

期刊介绍： The subject of the origin and early evolution of life is an inseparable part of the general discipline of Astrobiology. The journal Origins of Life and Evolution of Biospheres places special importance on the interconnection as well as the interdisciplinary nature of these fields, as is reflected in its subject coverage. While any scientific study which contributes to our understanding of the origins, evolution and distribution of life in the Universe is suitable for inclusion in the journal, some examples of important areas of interest are: prebiotic chemistry and the nature of Earth''s early environment, self-replicating and self-organizing systems, the theory of the RNA world and of other possible precursor systems, and the problem of the origin of the genetic code. Early evolution of life - as revealed by such techniques as the elucidation of biochemical pathways, molecular phylogeny, the study of Precambrian sediments and fossils and of major innovations in microbial evolution - forms a second focus. As a larger and more general context for these areas, Astrobiology refers to the origin and evolution of life in a cosmic setting, and includes interstellar chemistry, planetary atmospheres and habitable zones, the organic chemistry of comets, meteorites, asteroids and other small bodies, biological adaptation to extreme environments, life detection and related areas. Experimental papers, theoretical articles and authorative literature reviews are all appropriate forms for submission to the journal. In the coming years, Astrobiology will play an even greater role in defining the journal''s coverage and keeping Origins of Life and Evolution of Biospheres well-placed in this growing interdisciplinary field.