Curiosity investigated a topographic rise named Vera Rubin Ridge (VRR) in Gale Crater, for which a distinct hematite‐like signature was observed from orbit. However, the Chemistry and Camera (ChemCam) and Alpha Particle x‐ray Spectrometer (APXS) instruments on board the rover did not record any significant iron enrichment in the bulk of the ridge compared to previous terrains. For this study, we have reverified ChemCam iron calibration at moderate abundances and developed more accurate calibrations at high‐iron abundances using iron‐oxide mixtures in a basaltic matrix in order to complete the ChemCam calibration database. The high‐iron calibration was first applied to the analysis of dark‐toned diagenetic features encountered at several locations on VRR, which showed that their chemical compositions are close to pure anhydrous iron oxides. Then, we tracked iron abundances in the VRR bedrock and demonstrated that although there is no overall iron enrichment in the bulk of the ridge (21.2 ± 1.8‐wt.% FeO_T) compared to underlying terrains, the iron content is more variable in its upper section with areas of enhanced iron abundances in the bedrock (up to 26.6 ± 0.85‐wt.% FeO_T). Since the observed variability in iron abundances does not conform to the stratigraphy, the involvement of diagenetic fluid circulation was likely. An in‐depth chemical study of these Fe‐rich rocks reveals that spatial gradients in redox potential (Eh) may have driven iron mobility and reactions that precipitated and accumulated iron oxides. We hypothesize that slightly reducing fluids were probably involved in transporting ferrous iron. Mobile Fe²⁺ could have precipitated as iron oxides in more oxidizing conditions.

中文翻译：

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ChemCam在火星大风火山口维拉·鲁宾岭的高铁沉积基岩和成岩特征分析：校准和表征

好奇心研究了大风坑中一个名为Vera Rubin Ridge（VRR）的地形上升，从轨道上可以观察到一个独特的赤铁矿样特征。但是，与以前的地形相比，流动站上的化学和照相机（ChemCam）以及Alpha粒子X射线光谱仪（APXS）仪器并未在山脊的大部分区域记录到任何明显的铁富集。在本研究中，我们重新验证了ChemCam铁在中等丰度下的校准，并开发了使用玄武岩基质中的氧化铁混合物在高铁丰度下进行更准确的校准，以完成ChemCam校准数据库。高铁校准首先用于分析在VRR上多个位置遇到的暗色成岩特征，这表明它们的化学成分接近纯无水氧化铁。然后，_T）与下伏地形相比，其上段的铁含量变化更大，基岩中的铁丰度更高（FeO _T高达26.6±0.85-wt。％）。由于观察到的铁丰度的变化与地层不符，因此有可能参与成岩流体循环。对这些富含铁的岩石进行的深入化学研究表明，氧化还原电势（Eh）的空间梯度可能驱动了铁的迁移率以及沉淀和积累氧化铁的反应。我们假设在运输亚铁中可能涉及到略微减少的液体。在更多的氧化条件下，移动的Fe ²⁺可能已经沉淀为氧化铁。