Distribution maps of the OTES spectral types. (A) Ratio of 987/814 cm⁻¹; blue is OTES T1 and red is OTES T2. (B) Band depth at 440 cm⁻¹, modestly inversely correlated with R987/814 (see text for details). (C) Linear least squares modeled abundance distribution of T2 (where 0% = T1). The minimum and maximum scale bar values of (A) and (B) are ±2 standard deviations from the mean. All maps in this and subsequent figures are overlaid on the base map of Bennett et al. (2020); the yellow star denotes the Nightingale site.