First things first, this study is best used with hyperspectral data, especially ASTER. However, we couldn't download any ASTER data because we didn't have a QUAC license, so we decided to work with multi-spectral data since it was the easiest to download. We used Landsat-08 images dated November 2021 of Clayton, NV, and Salar de Atacama, Chile. Here we will compile a list of how we obtained our data.

 

• Pre-Processing

Once we downloaded the data, we used radiometric calibration on ENVI 5.6.2. Next, we needed to find what band ratios we would use to identify clay minerals since lithium is associated with clay rocks. We found a paper from the Arabian Journal of Geosciences that used several band ratios in an RGB composite. Next, we needed to find geologic maps of our respective study sites. We found a 1966 USGS geologic map of Clayton Valley, NV; unfortunately, we could not find a solid geologic map of Salar de Atacama, Chile.​

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Figure 1: Geologic Map of Clayton Valley, NV

 

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• Processing​

We applied the ferrous band ratio, clay mineral band ratio, and iron oxide band ratio on ENVI 5.6.2 and put them in an RGB composite. We analyzed hydrated volcanic tuff and clay rocks such as montmorillonite, hectorite, and spodumene with the RGB composite. According to Cypress, lithium is stored in these montmorillonite clays, so we found a spectral profile of montmorillonite on USGS and spectrally convoluted into our interpretation. We did the same to our hydrated volcanic tuff samples and the other clay rocks. ​

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Figure 2: Salar de Atacama, Chile, Landsat-08, RGB: Ferrous, clay minerals, iron oxide band ratios.

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• Interpretation

With the USGS spectral samples, we spectrally convoluted them into our spectral profiles and then compared them to our data. If our data correlated with the USGS data, we marked the pixel coordinates and saved the profiles for comparisons. However, if there weren't any correlations, we moved to another area. After analyzing sufficient data, we graphed our profiles in Excel to correlate with USGS. ​

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• ​​​​Results

With the data we analyzed, we used the data to correlate the spectral samples to known geologic formations. We made lithologic associations in Clayton Valley, NV, and in the salar in Chile. In Chile, we found world-class lithium-bearing deposits sitting along the eastern edge of the playa (green). In Clayton Valley, we didn't find an extensive build-up of clay, but we found ash flow drainage patterns into the playa and lots of vegetation up in the mountains surrounding the valley.