The Curiosity rover investigated a topographic structure known as Vera Rubin ridge, associated with a hematite signature in orbital spectra. There, Curiosity encountered mudstones interpreted as lacustrine deposits, conformably overlying the 300 m‐thick underlying sedimentary rocks of the Murray formation at the base of Mount Sharp. While the presence of hematite (α‐Fe₂O₃) was confirmed in situ by both Mastcam and ChemCam spectral observations and by the CheMin instrument, neither ChemCam nor APXS observed any significant increase in FeO_T (total iron oxide) abundances compared to the rest of the Murray formation. Instead, Curiosity discovered dark‐toned diagenetic features displaying anomalously high FeO_T abundances, commonly observed in association with light‐toned Ca‐sulfate veins but also as crystal pseudomorphs in the host rock. These iron‐rich diagenetic features are predominantly observed in “gray” outcrops on the upper part of the ridge, which lack the telltale ferric signature of other Vera Rubin ridge outcrops. Their composition is consistent with anhydrous Fe‐oxide, as the enrichment in iron is not associated with enrichment in any other elements, nor with detections of volatiles. The lack of ferric absorption features in the ChemCam reflectance spectra and the hexagonal crystalline structure associated with dark‐toned crystals points toward coarse “gray” hematite. In addition, the host rock adjacent to these features appears bleached and shows low‐FeO_T content as well as depletion in Mn, indicating mobilization of these redox‐sensitive elements during diagenesis. Thus, groundwater fluid circulations could account for the remobilization of iron and recrystallization as crystalline hematite during diagenesis on Vera Rubin ridge.

中文翻译：

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火星大风火山口维拉·鲁宾岭成岩过程中的铁迁移率

在好奇心流动站调查地形结构称为维拉鲁宾脊，以在轨道光谱的赤铁矿签名相关联。在那里，好奇号遇到了被解释为湖相沉积物的泥岩，顺着上层位于夏普山底部的默里地层300 m厚的沉积岩之上。虽然赤铁矿的存在（的α-Fe ₂ ö ₃）的混合物在原位由两个MASTCAM和ChemCam光谱观测和由CHEMIN仪器确认，既没有ChemCam也不APXS观察到的FeO任何显著增加_Ť（总铁氧化物）的丰度比其余的穆雷编队。相反，好奇心发现暗色成岩特征显示异常高的FeO _T通常在浅色调的硫酸钙矿脉中观察到丰度，但在宿主岩中也以晶体假晶形出现。这些富含铁的成岩特征主要在山脊上部的“灰色”露头中观察到，而这些露头缺乏其他维拉·鲁宾山脊露头的铁质特征。它们的组成与无水氧化铁一致，因为铁的富集与其他元素的富集无关，也与挥发物的检测无关。ChemCam反射光谱中缺乏铁吸收特征，与暗色调晶体相关的六边形晶体结构指向粗的“灰色”赤铁矿。此外，与这些特征相邻的基质岩石似乎已被漂白并显示出低FeO _T含量以及锰的耗竭，表明在成岩过程中这些氧化还原敏感元素的动员。因此，在维拉·鲁宾山脊的成岩作用过程中，地下水的循环可以解释铁的迁移和作为结晶赤铁矿的重结晶。