Characterization of Brazilian impact structures based on interpretations of Sentinel-1 C-band dual-polarization (VV and VH) data

Abstract. The known Brazilian impact structures are characterized using C-band Synthetic Aperture Radar (SAR) images from the Sentinel-1 satellites. After acquiring the dual-polarization (VV and VH) Ground Range Detected Dataset from a public repository, we applied standard processing techniques, including calibration, speckle noise reduction, terrain correction, and conversion of backscattering values to linear dB format. RGB visualizations of the polarimetric components were then generated. Our findings indicate that most backscattering in Brazilian impact structures is seemingly influenced by soil properties or vegetation cover. However, first-order structural elements (outer rim, annular basin, or central uplift) of Brazilian impact structures could be completely, or partially, identified in SAR images, including the northern part of the outer rim of Araguainha, the outer rim of Vargeão Dome and Santa Marta, the rim and inner rings on São Miguel do Tapuio, central uplifts in Serra da Cangalha and Riachão Ring, and the annular basin in Riachão Ring. Additionally, certain features, such as silicified sandstones in the central portions of Cerro do Jarau and Serra da Cangalha, as well as structural lineaments in the Santa Marta and Vargeão Dome structures, contribute to backscattering patterns as well. Overall, our results suggest that SAR imagery can be a valuable tool for structural mapping of impact structures. As L-band radar systems (e.g., ALOS PALSAR, JERS-1) have longer wavelength and greater ability to penetrate vegetation, we recommend that the joint use of C- and L-band data could improve geological mapping of impact structures.