The Origin of Abiotic Hydrocarbons in Seafloor Serpentinization Systems

海底蛇纹石化系统中非生物碳氢化合物的起源

• 批准号: 1634032
• 负责人: Frieder Klein
• 金额: $ 39.87万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1634032&HistoricalAwards=false
• 关键词: Origin; Abiotic; Hydrocarbons; Seafloor; Serpentinization

The origin and synthesis of higher chain hydrocarbons on Earth that formed the first components of life have been a major topic of research for decades. Hydrothermal vents on the seafloor have been proposed as one of the most likely places where life could have formed, but up to now, mechanisms by which long-chain and complex hydrocarbons that would be required to build a cell or nurture incipient life forms have only been speculated upon. This research builds off intriguing preliminary data from ultra-mafic hydrothermal vents on the Cayman Rise in the Caribbean Sea that indicate a significant proportion of the hydrocarbons coming out of hydrothermal vents in this region is generated not by biological processes, but abiotically (i.e., via water-rock interaction and other physical processes that do not involve living organisms or their byproducts). The research premise is that abiotic methane and longer chain hydrocarbons found in vent fluids in hydrothermal systems, dominated by the alteration reactions of ultramafic rocks, are formed in olivine-hosted secondary fluid inclusions that are leached during subsequent alteration of the mineral host. This is a startling, unconventional, and novel hypothesis that, if validated, will transform how we understand organic carbon compound formation in the subsurface of hydrothermal vent systems. To test this hypothesis, the abundance and carbon isotopic composition of low molecular weight hydrocarbons in secondary fluid inclusion in natural samples of basement rocks from a variety of seafloor ultra-mafic hosted hydrothermal systems will be analyzed. The fluid and gas contents of the fluid inclusions will be analyzed using gas chromatography-isotope ratio mass spectrometry. Cutting-edge nanometer-scale characterization of minerals formed in the fluid inclusions using X-ray dispersive spectroscopy on a scanning electron microscope and Raman confocal spectroscopy will allow constraints to be placed on fluid-rock interactions that regulate the chemical environment during organic compound synthesis. Thermodynamic models and calculations will be used to aid in the interpretation of the fluid-mineral equilibria and organic synthesis in the fluid inclusions. Broader impacts of the work include significant student training at the graduate and undergraduate level, with undergraduate interns being invited from the University of Puerto Rico to come work at the Woods Hole hydrothermal laboratory of the principle investigators for three months during the summer. These students will experience the full-bodied research experience from the selection of a project through collecting analytical data using state-of-the-art instrumentation to data analysis and presentation of results. Additional educational outreach will be carried out in the local school system via visits to K-12 classrooms and the development of a one-day short course on hydrothermal vents to be given at a local independent high school.

地球上构成生命最初组成部分的高链碳氢化合物的起源和合成一直是几十年来研究的主要课题。海底热液喷口被认为是最有可能形成生命的地方之一，但到目前为止，构建细胞或培育初期生命形式所需的长链和复杂碳氢化合物的机制仅存在被猜测。 这项研究以加勒比海开曼隆起超镁铁质热液喷口的有趣初步数据为基础，这些数据表明，从该地区热液喷口流出的碳氢化合物的很大一部分不是由生物过程产生的，而是非生物产生的（即通过水-岩石相互作用和其他不涉及生物体或其副产品的物理过程）。 研究前提是，在热液系统喷口流体中发现的非生物甲烷和长链碳氢化合物（主要是超镁铁岩的蚀变反应）是在橄榄石次生流体包裹体中形成的，这些包裹体在随后的矿物主体蚀变过程中被浸出。 这是一个令人震惊的、非传统的、新颖的假设，如果得到验证，将改变我们对热液喷口系统地下有机碳化合物形成的理解。 为了检验这一假设，将对来自各种海底超镁铁质热液系统的基岩天然样品中次生流体包裹体中低分子量碳氢化合物的丰度和碳同位素组成进行分析。 将使用气相色谱-同位素比质谱法分析流体包裹体的流体和气体含量。使用扫描电子显微镜上的 X 射线色散光谱和拉曼共焦光谱对流体包裹体中形成的矿物进行尖端纳米级表征，将限制流体-岩石相互作用，从而调节有机化合物合成过程中的化学环境。 热力学模型和计算将用于帮助解释流体包裹体中的流体-矿物平衡和有机合成。 这项工作的更广泛影响包括对研究生和本科生的重要学生培训，波多黎各大学邀请本科生实习生在夏季到主要研究人员的伍兹霍尔热液实验室工作三个月。 这些学生将体验到从项目选择到使用最先进的仪器收集分析数据，再到数据分析和结果呈现的全面研究经验。将通过参观 K-12 教室以及在当地一所独立高中开设为期一天的热液喷口短期课程，在当地学校系统中开展额外的教育推广活动。

项目成果

Chemical and isotopic analyses of hydrocarbon-bearing fluid inclusions in olivine-rich rocks

• DOI: 10.1098/rsta.2018.0431
• 发表时间: 2020-02-21
• 期刊: PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
• 影响因子: 5
• 作者: Grozeva, Niya G.;Klein, Frieder;Sylva, Sean P.
• 通讯作者: Sylva, Sean P.

Abiotic methane synthesis and serpentinization in olivine-hosted fluid inclusions

• DOI: 10.1073/pnas.1907871116
• 发表时间: 2019-09-03
• 期刊: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• 影响因子: 11.1
• 作者: Klein, Frieder;Grozeva, Niya G.;Seewald, Jeffrey S.
• 通讯作者: Seewald, Jeffrey S.