During 2018 and 2019, the Mars Science Laboratory Curiosity rover investigated the chemistry, morphology, and stratigraphy of Vera Rubin ridge (VRR). Using orbital data from the Compact Reconnaissance Imaging Spectrometer for Mars, scientists attributed the strong 860 nm signal associated with VRR to the presence of red crystalline hematite. However, Mastcam multispectral data and CheMin X‐ray diffraction (XRD) measurements show that the depth of the 860 nm absorption is negatively correlated with the abundance of red crystalline hematite, suggesting that other mineralogical or physical parameters are also controlling the 860 nm absorption. Here, we examine Mastcam and ChemCam passive reflectance spectra from VRR and other locations to link the depth, position, and presence or absence of iron‐related mineralogic absorption features to the XRD‐derived rock mineralogy. Correlating CheMin mineralogy to spectral parameters showed that the ~860 nm absorption has a strong positive correlation with the abundance of ferric phyllosilicates. New laboratory reflectance measurements of powdered mineral mixtures can reproduce trends found in Gale crater. We hypothesize that variations in the 860 nm absorption feature in Mastcam and ChemCam observations of VRR materials are a result of three factors: (1) variations in ferric phyllosilicate abundance due to its ~800–1,000 nm absorption; (2) variations in clinopyroxene abundance because of its band maximum at ~860 nm; and (3) the presence of red crystalline hematite because of its absorption centered at 860 nm. We also show that relatively small changes in Ca‐sulfate abundance is one potential cause of the erosional resistance and geomorphic expression of VRR.

中文翻译：

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火星盖尔陨石坑上墨累组和维拉鲁宾海脊的光谱、成分和物理特性


2018 年和 2019 年期间，火星科学实验室好奇号火星车研究了维拉鲁宾海脊 (VRR) 的化学、形态和地层学。利用火星紧凑型侦察成像光谱仪的轨道数据，科学家将与 VRR 相关的强 860 nm 信号归因于红色结晶赤铁矿的存在。然而，Mastcam 多光谱数据和 CheMin X 射线衍射 (XRD) 测量表明，860 nm 吸收的深度与红色结晶赤铁矿的丰度呈负相关，这表明其他矿物学或物理参数也在控制 860 nm 吸收。在这里，我们检查来自 VRR 和其他位置的 Mastcam 和 ChemCam 被动反射光谱，将深度、位置以及与铁相关的矿物学吸收特征的存在或不存在与 XRD 衍生的岩石矿物学联系起来。将 CheMin 矿物学与光谱参数相关联表明~860 nm 吸收与页硅酸铁的丰度具有很强的正相关性。粉末状矿物混合物的新实验室反射率测量可以重现盖尔陨石坑中发现的趋势。我们假设 VRR 材料的 Mastcam 和 ChemCam 观测中 860 nm 吸收特征的变化是由三个因素造成的：(1) 由于其约 800-1,000 nm 吸收而导致页硅酸铁丰度的变化； (2) 单斜辉石丰度的变化，因为它的带最大值在 ~860 nm 处； (3) 存在红色结晶赤铁矿，因为其吸收集中在 860 nm。我们还表明，硫酸钙丰度相对较小的变化是 VRR 抗侵蚀性和地貌表现的潜在原因之一。