Comment on Kawahara, H., Yoshida, H., Yamamoto, K., Katsuta, N., Nishimoto, S., Umemura, A., Kuma, R., 2022. Hydrothermal formation of Fe-oxide bands in zebra rocks from northern Western Australia. Chemical Geology 590 (2022), 120699

This comment questions an hypothesis for formation of the ornamental stone zebra rock from Ediacaran red shales of northwestern Australia as hydrothermal alteration zones. The hypothesis is falsified by absence of Eu anomalies in REE arrays, lack of associated carbonate, low degree of chemical weathering, associated soluble gypsum, strata concordance in narrow bands, low thermal stability of magnetization, modest diagenetic alteration, and patterns unlike liesegang banding. Rather than Cambrian hydrothermal veins, zebra rocks were gleyed paleosols with redox banding, from acid sulfate weathering at low temperature during the Ediacaran.

Automated summary

This comment refutes the hypothesis that zebra rocks in northwestern Australia were formed as hydrothermal alteration zones from Ediacaran red shales. The falsification is based on the absence of Eu anomalies in REE arrays, lack of associated carbonate, low degree of chemical weathering, presence of soluble gypsum, occurrence in narrow strata bands, low thermal stability of magnetization, moderate diagenetic alteration, and patterns unlike liesegang banding. Instead, zebra rocks were gleyed paleosols with redox banding formed by acid sulfate weathering during the Ediacaran at low temperature.