Mineralogy and Geochemistry of Ocelli in the Damtjernite Dykes and Sills, Chadobets Uplift, Siberian Craton: Evidence of the Fluid–Lamprophyric Magma Interaction

The study reports petrography, mineralogy and carbonate geochemistry stable isotopy of various types ocelli (silicate-carbonate globules) observed in the lamprophyres from Chadobets Uplift, southwestern Siberian craton. are related to REE-bearing Chuktukon carbonatites. On basis their morphology, relation with surrounding groundmass, we distinguish three ocelli: carbonate-silicate, containing carbonate, scapolite, sodalite, potassium feldspar, albite, apatite minor quartz (K-Na-CSO); carbonate–silicate ocelli, natrolite sodalite (Na-CSO); silicate-carbonate, feldspar phlogopite (K-SCO). K-Na-CSO present most evolved damtjernite irregular polygonal patches was distributed within groundmass; consist minerals identical ocelli. Carbonate calcite, Fe-dolomite ankerite high Sr concentration igneous-type REE patterns. Na-CSO Na-rich geochemical signature indicates loss component. phases calcite Fe-dolomite, they depleted LREE. K-SCO K-rich least-evolved damtjernite. Calcite has highest Ba lowest U-shaped pattern. textural, mineralogical features host rock can be interpreted as follows: (i) droplets an alkali–carbonate melt that separated residual alkali carbonate-rich highly damtjernite; (ii) late magmatic fluid once exsolved a then began dissolve; (iii) bubbles K-P-CO2 liberated almost-crystallised magma during magmatic–hydrothermal stage. shows could leach lamprophyre provide for mobility.