Silica Dissolution and Precipitation in Glaciated Volcanic Environments and Implications for Mars
Silica Dissolution and Precipitation in Glaciated Volcanic Environments and Implications for Mars
复制标题
冰川火山环境中的二氧化硅溶解和沉淀及其对火星的影响
DOI：
10.1029/2018gl078105
复制
发表时间：
2018
影响因子：
5.2
通讯作者：
T. Hamilton
中科院分区：
文献类型：
--
作者：
A. Rutledge;B. Horgan;J. Havig;E. Rampe;N. Scudder;T. Hamilton
火星表面展示了存在广泛且长期存在的冰冻圈的有力证据。对表面的观测已经确定了水-岩石相互作用产生的阶段，但冰川对观测到的蚀变矿物学的贡献尚不清楚。为了描述冰冷的早期火星上预期的化学变化，我们从陆地冰川火山岩中收集了水和岩石样本。我们将融水的地球化学测量与冰期岩石涂层的矿物学和化学联系起来。在这些地形中，相对于其他溶解的阳离子，水主要由溶解的二氧化硅组成，特别是在镁铁质地点。与镁铁质巨石上的冰川条纹相关的岩石涂层包含富含二氧化硅的成分，表明二氧化硅沉淀发生在冰下环境中。我们认为，火山基岩的冰川蚀变主要是由二氧化硅的高速率溶解和乳白二氧化硅的沉淀共同决定的。在火星上，冰冻圈驱动的化学风化可能是观察到的富含二氧化硅相的起源。
The surface of Mars exhibits strong evidence for a widespread and long‐lived cryosphere. Observations of the surface have identified phases produced by water‐rock interactions, but the contribution of glaciers to the observed alteration mineralogy is unclear. To characterize the chemical alteration expected on an icy early Mars, we collected water and rock samples from terrestrial glaciated volcanics. We related geochemical measurements of meltwater to the mineralogy and chemistry of proglacial rock coatings. In these terrains, water is dominated by dissolved silica relative to other dissolved cations, particularly at mafic sites. Rock coatings associated with glacial striations on mafic boulders include a silica‐rich component, indicating that silica precipitation is occurring in the subglacial environment. We propose that glacial alteration of volcanic bedrock is dominated by a combination of high rates of silica dissolution and precipitation of opaline silica. On Mars, cryosphere‐driven chemical weathering could be the origin of observed silica‐enriched phases.