Fig. 4: Infrared and image data showing felsic volcanic materials in the Eridania region. | Nature Astronomy

Fig. 4: Infrared and image data showing felsic volcanic materials in the Eridania region.

From: Diverse volcanism and crustal recycling on early Mars

Fig. 4

a, A THEMIS decorrelation-stretched image (I08708002) shows felsic materials as yellow and mafic material as purple surrounding a stratovolcano (labelled ‘SV’) at 170.3° E, 35° S. b,c, Surface emissivity spectra of the felsic (yellow) and mafic (purple) surfaces are compared to global average TES surface type 1 (ST1) and surface type 2 (ST2). Spline fits to the THEMIS data shown in b correspond to 9.36–9.5 μm for the yellow felsic surfaces and 10.74 μm for the purple mafic, and when compared to the plot shown in c of the spline fits for laboratory rocks and glasses, these values suggest high-silica compositions (yellow zone in c) as described in the main text. d,e, HiRISE data show that the felsic material is buff- to pink-coloured massive (d) to finely layered surface deposits (e), which we interpret as volcanic ash (images ESP_025301_1440 and ESP_023745_1465, respectively). Locations of HiRISE infrared-red-blue/green images are indicated with arrows in a.

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