Defining Surface Types of Mars Using Global CRISM Summary Product Maps

O M Kamps,F J A Van Ruitenbeek,R D Hewson,F D Van Der Meer

doi:10.1029/2019je006337

O M Kamps, F J A Van Ruitenbeek + Show 2 more

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https://doi.org/10.1029/2019je006337

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Abstract

AbstractFor many regions on Mars, the surface composition and its geological history have been debated in the literature. Because of the limited surface coverage of in situ measurements, either new data or new processing methodologies are required to get a better understanding of the Martian geology. This paper presents the results of a multivariate, unsupervised, analysis on underutilized CRISM (Compact Reconnaissance Imaging Spectrometer) multispectral mapping mode data set for surface type analysis. The devised summary products of Pelkey et al. (2007) and Viviano‐Beck et al. (2014) are averaged for the CRISM ~5° × 5° mosaic grids and used to analyze the variability in this data set. The averaged summary product values are studied using correlation coefficients calculated between summary products, as well as the correlation with dust coverage and elevation. The degree of correlation is used to interpret the summary products for the global distribution of mafic and secondary minerals and the effect of external factors such as ice, atmosphere, and dust coverage. With unsupervised clustering, all grid pixels are classified based on the spectral variability. These clusters are plotted as global maps and interpreted for geological variations in the CRISM data. Some clusters spatially correspond with previously recognized compositional distinct regions Northern Lowlands, Southern Highlands, Meridiani Planum, Syrtis Major, and Nili Fossae. Several other clusters are described here for the first time such as Solis Planum, Ophir Planum, and Hellas Basin. These regions cover known geological units, but the interpretation of the spectral variability is uncertain whether it relates to geological or external factors.

Highlights

To make the most accurate reconstruction of the global surface composition and geological history of Mars, information is required from all available orbital instruments
The results show that the CRISM multispectral mapping mode data are useful to assess the global surface geology
The novel approach with the use of summary products in combination with unsupervised data‐analysis techniques has proved to be a transparent method to test for the variability in the CRISM data and evaluate for the local geology

Summary

Introduction

To make the most accurate reconstruction of the global surface composition and geological history of Mars, information is required from all available orbital instruments. The global mapping data of CRISM (Compact Reconnaissance Imaging Spectrometer) has rarely been used for global surface analysis. Shallow absorption features in reflectance spectra and differences between orbital observations complicate the use of this data set. It is thought that this data set can provide important information to understand Mars's global geology. Most global surface composition studies that use infrared spectroscopy are performed with the TES (Thermal Emission Spectrometer) (Bandfield et al, 2000; Rogers et al, 2007) and OMEGA (Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité) instruments (Bibring et al, 2006; Ody et al, 2012; Riu et al, 2019).

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