Influence of the deep petroleum transformation on the CO2 budget of the atmosphere

Sammanfattning: Petroleum is an important component of the Earth’s crust and a necessary agent in human life. Due to fossil fuels usage in human activities, the carbon dioxide budget of the atmosphere is growing on the 4-5 GtC/year. However, could CO2 be generated from the“natural burning” of petroleum, resulting from the involvement of petroleum in subduction? During subduction, petroleum deposits, accumulated in the subducting slab, submerge down to the mantle and occur in the area with the extreme thermobaric conditions. As aresult, hydrocarbons undergo high temperature and pressure andcan be transformed into the oxidized form of carbon (such as CO2 and carbonates).The purpose of the present study is to investigate the role ofpetroleum in the deep processes of the Earth and explore, whether there is any influence from these processes on the carbon dioxide budget of the atmosphere. In the current thesis, the results of the experimental work are presented, which model the behavior of the petroleum hydrocarbons in the thermobaric conditions and surrounding environment of the lower part of the Earth's crust and upper mantle in the depth range of 20-300 km (320-2,000 °C, 0.7-9.5 GPa). High pressure,high-temperature experiments were carried out, using diamond anvil cells and a Toroid-type large reactive volume unit. The stability and possible transformations of hydrocarbon systems at the presence of slab and mantle surrounding, and fate of carbon, submerged down into the Earth's interiors in the form of hydrocarbon during subduction, was investigated.The obtained experimental results demonstrate the chemical transformation of petroleum during subduction. It was discovered, that CO2 was not formed from hydrocarbons during subduction. Hydrocarbons could react with the surrounding mantle and slab and transform into more sustainable compounds at thermobaric and Redox conditions, corresponding with the Earth’s deep interior. However, this process does not have any significant influence on the carbon dioxide budget of the atmosphere.