Calcium cycle; Calcium carbonate; Calcium oxalate; Dating methods; Stable isotopes; Terrestrial carbonates; Africa; Quaternary
Van Thuyne John, Verrecchia Eric P. (2021), Impacts of fungus-growing termites on surficial geology parameters: A review, in Earth-Science Reviews
, 223, 103862-103862.
Van Thuyne John, Darini Isacco, Mainga Ali, Verrecchia Eric P. (2021), Are fungus-growing termites super sediment-sorting insects of subtropical environments?, in Journal of Arid Environments
, 193, 104566-104566.
Vittoz Pascal, Pellacani Federico, Romanens Rémy, Mainga Ali, Verrecchia Eric P., Fynn Richard W.S. (2020), Plant community diversity in the Chobe Enclave, Botswana: Insights for functional habitat heterogeneity for herbivores, in KOEDOE - African Protected Area Conservation and Science
, 62(1), 1-17.
Romanens Rémy, Pellacani Federico, Mainga Ali, Fynn Richard, Vittoz Pascal, Verrecchia Eric P. (2019), Soil diversity and major soil processes in the Kalahari basin, Botswana, in Geoderma Regional
, 19, e00236-e00236.
Diaz N., Armitage S.J., Verrecchia E.P., Herman F. (2019), OSL dating of a carbonate island in the Chobe Enclave, NW Botswana, in Quaternary Geochronology
, 49, 172-176.
Mokatse Thuto, Diaz Nathalie, Shemang Elisha, Van Thuyne John, Vittoz Pascal, Vennemann Torsten, Verrecchia Eric P., Landscapes and Landforms of the Chobe Enclave, Northern Botswana, in Eckardt Frank (ed.), Springer Nature, Switzerland, 1-29.
In the northern Kalahari desert in Botswana, enigmatic Quaternary formations enriched in carbonate are observed in the landscape. These deposits are in the geographical area of large (paleo-) rivers having their source in the Equatorial zone. In the past, the watershed was related to an inland lacustrine basin, the Makgadikgadi Lake. One of the most intriguing characteristics of these deposits is their large abundance of carbonate nodules and/or beds, in a place where the closest limestone outcrop is several hundreds to thousands of km away. Indeed, in Botswana, large areas are covered with Kalahari sands, but in some places, thick carbonate layers and paleosols unexpectedly outcrop in this predominantly quartz environment. These formations, incorrectly identified as "calcrete" in the past, seem to be palustrine/shallow lacustrine deposits, probably related to the dynamics of the (paleo-)Zambezi-Chobe and/or Linyanti rivers during the Late Quaternary.The proposed research will be conducted to tackle these objectives :(i) The various carbonate deposits need to be properly studied, as they are usually considered as calcrete instead of palustrine limestones. Consequently, the first task targets the study of the various types of deposits in the Chobe Enclave, including diatomites, fluvial and eolian sands, based on modern and conventional methods used in sedimentology/biogeochemistry. (ii) The next aim concerns the Ca sources. How did Ca accumulate enough to contribute to the precipitation of almost pure Ca-carbonate phases? (iii) The third task, as a consequence, assesses the origin/conditions of the unexpected succession of silicate- and carbonate-rich phases: climatic, tectonic, tectono-climatic, lacustrine, palustrine, eolian ? (iv) Finally, dating of the various deposits in the Chobe Enclave will be assessed in order to propose a chronological sequence based on various methods, i.e. 14C on carbonate and organic matter, OSL, ESR, U-Th, and compare results to the Southern African chronological framework.In conclusion, the aim of the project is to propose a genetic model that can explain the unexpected presence of calcium carbonate in carbonate-free and acidic endorheic landscapes during the Late Quaternary. This research will improve our knowledge of the relationships between regional scale climatic variability and externally-forced climate change in Africa. In addition, conclusions will contribute to understanding some surprising carbonate paleosols in carbonate-free landscapes from the Earth’s deep time and their potential relationships with atmospheric pCO2 and life.