Long-term analog of carbonation in travertine from Uleimat Quarries, Central Jordan

Quaternary travertine capping the metamorphic (cement) zones in Uleimat Quarries, central Jordan, has been precipitated from hyperalkaline paleogroundwaters. Such waters are similar to the cement pore water and to the present day hyperalkaline seepages (pH 12.5) in Maqarin, north Jordan. The isotopic depletions observed in Uleimat travertine, with δ¹³C values as low as −25.45‰, suggest that they have been precipitated during CO₂ uptake by highly alkaline calcium hydroxide waters. The travertine in Uleimat Quarries indicates a long-term analog of carbonation and remobilization of silica in cementitious barriers for radioactive waste repositories. The presence of Cr-rich smectites and relatively high levels of Cr (4.1%), V (657 ppm), Ni (163 ppm), Zn (634 ppm) and U (34 ppm) in the green travertine and the associated opaline silica phases suggests the use of the Uleimat travertines as analogs with the repository disturbed zone. Smectites and silica phases are expected to be a sink for alteration products in the late stage evolution of a high pH plume. Co-precipitation of these elements in mineral phases is of great importance to control the concentration of these elements in groundwater.