MUD VOLCANOES FROM ROMANIA: GEOLOGICAL AND GEOCHEMICAL APPROACHES.

Mud volcanoes occur both on land and oceans, but their occurrence is generally known on limited areas. Many of the European mud volcanoes structures are known from Romania, where their number exceeds 40. The most impressive and famous of the Romanian mud volcanoes are situated near the Buzău town, at Berca, in the Romanian Carpathian bend area. Other Romanian mud volcanoes are situated in the Transylvanian Basin and in the SW part of the country (Banat region). This paper presents the geological setting, including the lithofacies of mud volcano structures and new geochemical acquired data on methane and CO₂ emissions. We concluded that the shape and size of the mud volcanoes are linked to the fluid pressure, the underground water, the passage through clayey deposits and the presence of hydrocarbons or salt. Therefore, the occurrence of the mud volcanoes in the Berca region is related to the existence of Berca anticline, hydrocarbons and the salt diapirs of the Inner Foredeep of the Eastern Carpathians. Besides, the subsurface deposits of the region comprise various sedimentary types, i.e., sandstones, clays, marls and sands, mainly Miocene up to Pliocene in age. Most probably, the intensity and frequency of the eruptions is given by the size of the gas pore-pressure. The measurements in the mud volcano region of Berca indicate that the methane and CO₂ flux displays a high variability, linked to fluid seepage episodes. [ABSTRACT FROM AUTHOR]