Radiocarbon Age of Soils in Oases of East Antarctica

Abstract

This article discusses radiocarbon dating results for soils and soil-like systems in the East Antarctic oases, including Schirmacher, Thala Hills, and Larsemann Hills. The organic matter of endolithic and hypolithic systems, soils of wind shelters, and soils under moss-algae vegetation were dated along with micro- and macroprofiles. Organic matter pools formed under extreme climatic conditions and originated not from vascular plants but from cryptogamic organisms, and photoautotrophic microbes have been identified within the oases of the East Antarctica. The organic matter of the most of East Antarctic soils is young and cannot reach a steady state because of the high dynamism in the soil cover due to active erosion. The oldest soil organic matter in East Antarctica was found in the soils formed in wind shelters and endolithic soil-like systems under the protection of consolidated rock surfaces. According to our data, the maximal duration for the formation of organic matter profiles within the oases of East Antarctica is ~500 yr, which is similar to the age determined for High Arctic soils in Eurasia. The absence of older soils, comparable with the Holocene deglaciation, can be due to the extreme conditions resulting in occasional catastrophic events that destroyed the soil organic horizons.

Soils of East Antarctic oasis: interplay of organisms and mineral components at microscale

“…Very similar micromorphological observations about organic components were made in the Lithosols of Western Antarctica (Vlasov et al, 2005), including findings of organic coatings on coarse mineral grains (Abakumov et al, 2013). However, radiocarbon dating of the organic material in these profiles has produced 14 C ages in the range from dozens to 1000 yr BP (Zazovskaya et al, 2017). We conclude that undecomposed organic materials could persist in these extreme cold landscapes with the residence times of hundreds of years, despite limited moisture and predominantly oxidative soil environment.…”

“…in the radiocarbon age with depth, with the pMC (percent Modern Carbon) of 100% in the upper peaty horizons; the latter have the functioning period of 50-60 years, which increases up to 400 years in the B horizons of soils formed under moss communities (Zazovskaya et al, 2017).…”

“…The quoted uncalibrated dates have been given in radiocarbon years before 1950 (years BP), using the 14 C half-life of 5568 years. The details of the dating technique and processing of results were presented earlier (Zazovskaya et al, 2017), here we discuss the significance of SOM radiocarbon ages in the context of micromorphology of organic components.…”

“…The attempts were made to integrate the soil information on the continental scale (Bockheim and Ugolini, 1990;Balks et al, 2013) as well as to compare Antarctic and Arctic soil mantles (Tedrow, 1991). In the early 2000s, a team of Russian soil scientists began studying soils near Russian Research Stations within the coastal region of East Antarctica, on some nunataks, in Wohlthat Mountains (Queen Maud Land) and barely accessible parts of West Antarctica (Abakumov, 2010;Gilichinsky et al, 2010;Goryachkin et al, 2012;Abakumov et al, 2013;Lupachev and Abakumov, 2013;Mergelov, 2014;Zazovskaya et al, 2015Zazovskaya et al, , 2017. The new data improved the understanding of the weathering and soil formation processes under extreme conditions, that was reflected in the latest international monograph on Antarctic soils (Bockheim, 2015).…”

Alteration of rocks by endolithic organisms is one of the pathways for the beginning of soils on Earth

“…Sample preparation procedures that we applied to date organic matter derived from the endolithic organo-mineral horizons are described in details in Zazovskaya et al . 63 . 14 C AMS measurements were implemented at the Center for Applied Isotope Studies, University of Georgia, USA.…”