Sulfide oxidation as a trigger for rhyolite weathering and paleosol formation in Devonian (Voronezh High, South Russia)

During Late Devonian Voronezh Land was one of the main volcanic centers of Central Devonian Field. Earlier eruptions on the given territory have not been documented. This paper presents the detailed multidisciplinary study of the Pre-Eifelian paleosol developed from rhyolite lava deposited on the contact with the Proterozoic basement in Shkurlat granite quarry (Voronezh region, Russia). Discovered paleosol includes abundant coalified and partly substituted by pyrite allochthonous remnants of Nematasketum and Prototaxites. Main part of them had an outstanding preservation of tissues. Along with typical for rhyolite a quartz dominance, paleosol contains in situ developed kaolinite, gypsum, goethite, jarosite. Abundant Fe-nodules concentrated in the second half part of the shallow (-50 cm) paleosol profile are composed of gypsum, goethite and metastable Fe-sulfates - jarosite and voltaite. Based on a complex of analytical characteristics, the discovered paleosol was attributed to acidic sulfate soil. The development of paleosol was initiated by pyrite oxidation which played the role of trigger. Being gypseous, paleosol bears the characteristics which are typical for paleosol of humid type. Based on geochemical data (CIA, CIA-K, PWI indexes) the obtained climatic parameters correspond to a subtropical climate with MAP 1200-1300 mm and MAT - 17 degrees C.

Automated summary

This paper presents a detailed multidisciplinary study of a Pre-Eifelian paleosol developed from rhyolite lava in Voronezh region, Russia. The paleosol contains abundant fossils and minerals and exhibits characteristics of acidic sulfate soil. Based on geochemical data, the researchers infer that it corresponds to a subtropical climate with an annual precipitation of 1200-1300 mm and an average temperature of -17 degrees C.