Investigator:

Jennifer Kasbohm

Advisor: David Evans

Description:

The Mesoproterozoic sediments and extrusive igneous bodies of the Sinclair Group in southern Namibia may yield greater insight into Precambrian tectonic processes, such as the formation of the supercontinent Rodinia. Greater paleomagnetic sampling of Sinclair rocks with magnetic minerals is required in order to discern the paleogeography of the Kalahari Craton. With this purpose in mind, I pursued a geological classification of the Sinclair Group for my project for the course Observing the Earth From Space. This project will expand the analysis to adjacent regions and enhance classification techniques.

Guided by GPS points and spectral data from rocks collected in the field, two different supervised classifications were performed using an ASTER image. The first utilized the 15 m resolution visible and near-infrared bands to identify landscape features to construct regions of interest, overlain on the full spectral stack of ASTER bands, and input into a Maximum Likelihood classification. The second utilized ASTER’s thermal bands to create ROIs from a false-color image that differentiated silicate, carbonate, and basic rocks.

When compared with a geologic map created from field observations, it was found that carbonates and mafic rocks were well-classified, while silicates and felsic rocks were confused. The full stack classification was more successful at determining the formation to which the rock belonged, while the thermal classification could only discern rock type. Dykes, which are effective targets for paleomagnetic sampling, could not be grouped into their own class without introducing significant error to the classified image. However, the high spatial resolution of the ASTER imagery allows for remote reconnaissance of new sampling sites.