University of Twente Student Theses


Characterising the compositional variations of the Martian Northern Lowlands: Insights form CRISM and OMEGA datasets

Marshal, Rachel Martina Fernando (2020) Characterising the compositional variations of the Martian Northern Lowlands: Insights form CRISM and OMEGA datasets.

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Abstract:In the study of Kamps et al., (2019), Martian global surface types are classified based on the downsampled 5 °x 5° averaged CRISM multispectral summary product data. The surface type classification map indicated two units for the Northern Lowlands, i.e., the Northern Lowlands Unit and the Northern Transition Unit. Since subtle compositional variations may not be apparent in the averaged resolution, my research will investigate the findings of Kamps et al., (2019) in particular – the Northern Lowland and Transition Unit in the original data resolution of CRISM multispectral products. This thesis will focus on characterising the compositional variations prevailing over the Northern Lowlands of Mars, in particular, the region Acidalia Planitia. In addition to the regional characterisation of the study area using the CRISM dataset, my thesis also characterises local variations using the OMEGA dataset. The composition of the Northern Lowlands has been studied before using data from the Thermal Emission Spectrometer and the Observatoire pour la Mineralogie, l’Eau, les Glaces et l’Activite – OMEGA but not using the multispectral dataset of the CRISM. In my study, a principal component analysis (PCA) is carried out on the CRISM summary product data. Significant products contributing to the variance in the regions are identified, following which the regions exhibiting patterns in the PCA composites are demarcated. The mean spectra of the demarcated regions are analysed. A continuous downward negative spectral slope is identified as a ubiquitous characteristic of the Northern Lowlands. The parameter ISLOPE1 is designed to pick up this downward spectral slope, but the product ISLOPE1 has limitations that it only samples reflectances at two wavelengths: 1815nm and 2530nm. In order to improve the quantification of the spectral slope, an alternate refined spectral slope parameter that measures the slope of the regression line fitted through the wavelengths 1000nm – 2000nm is introduced in my study. The mean spectral slope of the CRISM reflectance strips shows an increase in absolute value as we move northward from the Transition Unit into the Northern Lowland Unit. The mineralogical interpretation of the spectral slope is that it might be indicative of a weathering rind on basaltic glass or glassy basalt. This interpretation favours a weathered origin over an andesitic origin for the surface type associated with the Northern Lowlands. Apart from the spectral slope, the Transition unit shows patterns of higher interpreted content of the olivine associated with crater ejecta, higher albedo, higher values for the dust products and shows an increase in elevation, in comparison to the Northern Lowland Unit. Lastly, localised patterns are identified at the Highland-Lowland dichotomy and Mawrth Vallis using the OMEGA dataset. These regions indicate a presence of phyllosilicate minerals that may be remnants of an altered Noachian crust that is only locally exposed since much of the Northern Lowlands has been covered by younger Hesperian material. These localised regions may be indicative of a regional aqueous alteration of the Noachian crust in the ancient history of Mars. Following the Noachian period, the Northern lowlands have been extensively reworked by influx from the Highlands via the Circum-Chryse outflow channels and relatively recent weathering processes that could have been the reason for the ubiquitous spectral slope identified in this thesis.
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
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