The influence of tectonic activity on clathrate destabilisation: Microthermometry and Raman insights from seep carbonates in the Alps?Apennines tectonic knot

The formation of carbonate build-ups associated with seafloor methane vents – where microbially mediated sulphate-dependent anaerobic oxidation produces alkalinity is well documented in modern marine environments and the geologic record. However, triggering event(s) behind processes leading to hydrocarbon disequilibrium, seeping consequent deposition seep-carbonates remain poorly constrained. This contribution characterises salinity, geochemistry temperature framework a suit fluid inclusions from hydrocarbon-derived seep-carbonate veins, collected Marmorito Formation Monferrato Hills, NW Italy. datasets yield evidence three different precipitation events, which comprise porous structures composed bladed calcites aggregated spherules aragonite. Fluid analysis shows presence heterogeneous entrapment immiscible fluids proving paleo-dissolution suite complex hydrocarbons, have wide range closing starting at ca. 60°C. These physical chemical conditions are considered indicate driven by disequilibrium hydrocarbon-bearing compounds temperatures much warmer than background ambient bottom waters (ca. 1 5°C) due influence Late Oligocene Early Miocene tectonic compression junction southern Alps Apennines.