Farr Orion, Elzinga Evert J, Yee Nathan
Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, 08854, USA.
Department of Earth and Environmental Sciences, Rutgers University-Newark, Newark, NJ, 07102, USA.
Geochem Trans. 2022 Dec 29;23(1):3. doi: 10.1186/s12932-022-00080-y.
In this study, we investigated Ni, Zn, and Co mineralogical incorporation and its effect on green rust transformation to magnetite. Mineral transformation experiments were conducted by heating green rust suspensions at 85 °C in the presence of Ni, Zn, or Co under strict anoxic conditions. Transmission electron microscopy and powder X-ray diffraction showed the conversion of hexagonal green rust platelets to fine grained cubic magnetite crystals. The addition of Ni, Zn, and Co resulted in faster rates of mineral transformation. The conversion of green rust to magnetite was concurrent to significant increases in metal uptake, demonstrating a strong affinity for metal sorption/co-precipitation by magnetite. Dissolution ratio curves showed that Ni, Zn, and Co cations were incorporated into the mineral structure during magnetite crystal growth. The results indicate that the transformation of green rust to magnetite is accelerated by metal impurities, and that magnetite is a highly effective scavenger of trace metals during mineral transformation. The implications for using diagenetic magnetite from green rust precursors as paleo-proxies of Precambrian ocean chemistry are discussed.
在本研究中，我们研究了镍、锌和钴的矿物学掺入及其对绿锈转变为磁铁矿的影响。通过在严格缺氧条件下，于85°C加热含镍、锌或钴的绿锈悬浮液进行矿物转化实验。透射电子显微镜和粉末X射线衍射显示六方绿锈片状物转变为细粒立方磁铁矿晶体。镍、锌和钴的添加导致矿物转化速率加快。绿锈向磁铁矿的转化与金属吸收的显著增加同时发生，表明磁铁矿对金属吸附/共沉淀具有很强的亲和力。溶解比曲线表明，镍、锌和钴阳离子在磁铁矿晶体生长过程中掺入矿物结构。结果表明，金属杂质加速了绿锈向磁铁矿的转变，并且磁铁矿在矿物转化过程中是一种高效的痕量金属清除剂。讨论了将来自绿锈前体的成岩磁铁矿用作前寒武纪海洋化学古代理的意义。
