Collaborative Research: Rates of Carbonate Formation in the Samail Ophiolite, Oman: Implications of Ultramafic Weathering for the Carbon Cycle

合作研究：阿曼萨迈伊蛇绿岩中碳酸盐的形成速率：超镁铁质风化对碳循环的影响

• 批准号: 1049950
• 负责人: Kenneth Sims
• 金额: $ 2.96万
• 依托单位: University of Wyoming
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-01 至 2013-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1049950&HistoricalAwards=false
• 关键词: Collaborative; Research; Rates; Carbonate; Formation

In the last few years, considerable attention has been focused on carbon capture and storage to mitigate anthropogenic input of atmospheric CO2. One proposed option for mitigation is to increase conversion of CO2 gas to stable, solid carbonate minerals during chemical weathering of tectonically exposed mantle rock (or peridotite). While natural carbonation of peridotite is commonly observed, its rate, and therefore the rate of CO2 uptake via this weathering mechanism, is poorly known. Determining the natural rate of peridotite carbonation is critical for understanding the influence of this potentially important ?sink? in the global carbon cycle. The natural peridotite carbonation rate is also an essential, but poorly constrained, parameter in calculations evaluating the viability of using artificially-enhanced, in situ alteration of peridotite to mitigate the buildup of anthropogenic input to atmospheric CO2.The primary objective of this research is to determine natural carbonation rates of exposed mantle peridotites. The Samail Ophiolite, Oman, is one of the largest and best-exposed ophiolites in the world, and hence is an ideal natural laboratory for investigating natural carbon storage in mantle peridotites. The research team has selected and carefully mapped eight sites that include roadcuts exposing carbonate veins, travertine deposits, and one site located on the natural peridotite weathering surface and containing abundant carbonate veins. The work plan consists of determining the ages of carbonates using two independent radiogenic dating techniques: 14C (for carbonates as old as ~50,000 years) and 238U-230Th (for carbonates as old as ~350,000 years). In addition, they will determine exposure ages for the host mantle peridotite to test the hypothesis that carbonate weathering primarily occurs in a thin weathering horizon that keeps pace with erosion rates. This project constitutes the Ph.D. thesis research for MIT/WHOI Joint Program student Evelyn Mervine. An improved understanding of natural carbonate formation in ultramafic rocks will aid efforts to develop CO2 capture and storage in ultramafic rocks to offset anthropogenic CO2 emissions and mitigate global climate change.

在过去的几年中，大大关注碳捕获和存储，以减轻大气二氧化碳的人为输入。缓解措施的一种建议是，在构造暴露的地幔岩（或橄榄岩）化学风化过程中，将二氧化碳气体转化为稳定的固体碳酸盐矿物质。虽然通常观察到橄榄岩的自然碳酸化，但其速率，因此通过这种风化机制的二氧化碳吸收速率是鲜为人知的。确定橄榄岩碳酸的自然速率对于理解这种潜在重要的水分的影响至关重要吗？在全球碳循环中。自然橄榄岩碳酸化速率也是评估使用人工增强的可行性的必不可少的但受到限制的参数。橄榄岩原位改变了橄榄岩的原位改变，以减轻人类学输入到大气中的CO2。这项研究的主要目标是确定自然碳酸疫苗的自然碳化速率。阿曼的萨梅尔蛇绿岩是世界上最大，曝光最高的蛇绿岩之一，因此是研究地幔橄榄岩中天然碳储存的理想天然实验室。研究团队已经选择并精心绘制了八个地点，其中包括露出碳酸盐静脉，石灰华沉积物以及位于天然橄榄岩风化表面上的一个地点，并含有丰富的碳酸盐静脉。该工作计划包括使用两种独立的放射性约会技术来确定碳酸盐的年龄：14C（对于大约50，000年的碳酸盐）和238u-230th（对于年龄〜350，000年的碳酸盐）。此外，他们还将确定宿主地幔橄榄岩的暴露年龄，以检验以下假设：碳酸盐风化主要发生在稀薄的风化范围内，从而保持侵蚀率。该项目构成博士学位。麻省理工学院/WHOI联合计划的学生Evelyn Mervine的论文研究。对超镁铁质岩石中天然碳酸盐形成的深入了解将有助于努力开发超镁铁质岩石中的二氧化碳捕获和储存，以抵消人为的二氧化碳排放并减轻全球气候变化。