Occurrence of secondary minerals at Tharsis Montes of Mars: A critical assessment

1Adnan Ahmad,1Raj Patel,1Bhaswati Deka,2Rohit Nagori,2A.S.Arya,1Archana M.Nair
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.114953]
1Department of Civil Engineering, Indian Institute of Technology Guwahati, Assam, India
2Space Application Centre, Indian Space Research Organization, Ahmedabad, India
Copyright Elsevier

Identification of phyllosilicates on Mars suggests the existence of an aqueous environment, indicating an active period in its evolutionary history. This study analysed the surface mineralogy of caldera and flank regions of Tharsis Montes using remote spectral analysis. Though a thick layer of dust obscures the surface of Tharsis volcanic province, relatively lesser dust regions provide a unique window for exploration. The reflectance data obtained from CRISM onboard Mars Reconnaissance Orbiter in the visible-infrared region is used for the mineralogical study. Spectral parameter indices were used to identify the distribution of minerals over the caldera and flank regions of Tharsis Montes. The spectral characterisation indicates the well-distributed presence of mafic minerals such as olivine with low-calcium pyroxene and plagioclase with the sparse presence of high-calcium pyroxene in the region. The dusty region, typically with a high TES DCI index and low thermal inertia values in the Tharsis Montes, shows a high concentration of olivine. Few regions identified as comparatively dust-free at the caldera and flank show the presence of secondary mafic minerals like Fesingle bondMg bearing phyllosilicates. Our spectral analysis using nonlinear mixing models with the MICA spectral library indicates the occurrence of absorption features characteristic of hydrated minerals. The occurrence of the secondary mafic minerals, especially the phyllosilicates on Tharsis Montes suggest active weathering or hydrothermal alteration from episodic volcanic activity over time. Many factors on the Martian surface obstruct clean and noise-free data acquisition, pointing to the necessity of validating interpretations using multiple data sets.

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