Investigation of the Dashigil mud volcano (Azerbaijan) using beryllium-10

Abstract

We collected and analyzed five sediments from three mud volcano (MV) vents and six suspended and bottom sediment samples from the adjoining river near the Dashgil mud volcano in Azerbaijan for 10Be. These three MV are found among the 190 onshore and >150 offshore MV in this region which correspond to the western flank of the South Caspian depression. These MVs overlie the faulted and petroleum-bearing anticlines. The 10Be concentrations and 10Be/9Be ratios are comparable to the values reported for mud volcanoes in Trinidad Island. It appears that the stable Be concentrations in Azerbaijan rivers are not perturbed by anthropogenic effects and are comparable to the much older sediments (mud volcano samples). The 10Be and 9Be concentrations in our river sediments are compared to the global data set and show that the 10Be values found for Kura River are among the lowest of any river for which data exist. We attribute this low 10Be concentration to the nature of surface minerals which are affected by the residual hydrocarbon compounds that occur commonly in the study area in particular and Azerbaijan at large. The concentrations of 40K and U-Th-series radionuclides (234Th, 210Pb, 226Ra, and 228Ra) indicate overall homogeneity of the mud volcano samples from the three different sites. Based on the 10Be concentrations of the mud volcano samples, the age of the mud sediments could be at least as old as 4myr.