A Paleosol on a Pre-Cambrian Ferruginous Quartzite Weathering Crust (Stary Oskol, Belgorod Region, Russia)

• Published in: Paleontological journal 2021-12, Vol.55 (12), p.1476-1490
• Main Authors: Alekseeva, T. V., Alekseev, A. O., Mitenko, G. V.
• Format: Article
• Language: English
• Subjects: Acidic soils; Aluminum; Amorphous silicon; Aridity; Cambrian; Climate; Concretions; Crusts; Earth and Environmental Science; Earth Sciences; Fragments; Gypsum; Haematite; Hematite; Iron; Kaolinite; Magnetic anomalies; Metamorphic rocks; Oxidation; Paleoclimate; Paleontology; Paleosols; Plant cover; Pyrite; Quartzite; Soil; Soil characteristics; Soil formation; Soils; Sulfides; Sulphides; Vegetation cover; Weathering
• ISSN: 0031-0301; 1555-6174
• DOI: 10.1134/S0031030121120054

This study describes the results of a detailed study (morphology, XRD, Mössbauer and FTIR- spectroscopies, SEM-EDS) of paleosol (PS) developed at the surface of Pre-Cambrian weathering crust of ferruginous quartzite (Kursk Magnetic Anomaly Region). The age of soil formation is estimated as pre-Eifelian. Being developed from pyrite bearing metamorphic rock, the PS includes the characteristics of several pedogenic units, mostly Lithosol and acid sulphate soil. Its specific feature is intensive pedogenesis within the rock at a depth of 10–15 cm, and negligible at the surface. The PS was developed under low monotypic vegetation cover. The sub-micromorphology of plant fragments shows that they belong to either primitive Lycopodiophyta or to Propteridophyta . The similarity between the micromorphology of fragments of surface and subsurface parts of plants shows the development of primitive roots. Azonality of soil characteristics makes paleoclimate reconstructions difficult. For instance, evidence of deep mineral weathering, such as quartz and hematite dissolution, the formation of kaolinite, and amorphous Si, Al, Fe mineral crusts development may reflect climate humidity or aggressive weathering caused by sulfide oxidation. The newly formed gypsum could be a product of deep pyrite oxidation rather than accumulation due to climate aridity. However, its preservation suggests non-humid (semi-arid), rather than humid environments.