铜同位素追踪了克拉顿地幔根的新生态时代氧化过程
Chunfei Chen1,2, Stephen F Foley3,4, Svyatoslav S Shcheka3
1State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, 430074, Wuhan, China. chfchen2016@hotmail.com.
Nature communications
|May 21, 2024
概括
随着时间的推移,下层石化层变得更加氧化,从富含甲的环境过渡到富含二氧化碳的环境. 这种氧气流动性转移影响了北大西洋地中的金属稳定性和石质层进化.
科学领域:
- 地质化学 地质化学
- 石化学 石化学是一门学科.
- 地球科学 地球科学 地球科学
背景情况:
- 在较低的岩石层中,氧气流动性 (fO2) 对于钻石形成,化过程和石层进化至关重要.
- 这种深层岩层的时态氧化还原演变仍然不太了解.
研究的目的:
- 为了重建北大西洋巨的石化层-石化层边界 (LAB) 源中的氧气流动性 (fO2) 和挥发性物种化.
- 为了了解地质时间的下大陆石化层的氧化还原演变.
主要方法:
- 分析铜同位素 (δ65Cu) 在约1.4 Ga的灯矿石和<0.59 Ga的低和性岩石中.
- 解释 δ 65 Cu 变化以推断地幔来源中的 FO 2 和主导的挥发物种 (CH 4 / CO 2) .
主要成果:
- 介质前时代的灯矿石 (大约1.4亿年前) 表示金属和,减少的LAB (CH4+H2O主导) 具有较低的δ65Cu值.
- 新新生代的性岩 (< 0.59 亿年) 呈现了类似地幔的 δ 65 Cu,这意味着更氧化的 LAB (CO 2 + H 2 主导) 和金属不稳定.
- 一个显著的氧化事件,至少2.5log单位在FO2中,发生在LAB在Neoproterozoic.
结论:
- 北大西洋石坑下方的石化层-石化层边界从中原生态到新原生态经历了显著的氧化.
- 这种氧化事件使CO2稳定在CH4上,影响地幔地质化学,并可能在全球范围内发生在地根中.
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