Numerical Simulation on Authigenic Barite Formation in Marine Sediments

Abstract

Submarine cold seep and its associated authigenic minerals in sediment are meaningful to indicate the existence of underlying natural gas hydrate. The anaerobic oxidation of methane (AOM) is coupled with sulfate reduction (SR) and influences the dissolution and precipitation of barite. However, the forming mechanism of barite is not yet clearly understood. In order to investigate the forming process of authigenic barite and its relationship with methane leakage flux, based on the measured data of the Qiongdongnan Basin in the Northern slope of the South China Sea, we constructed a 1D model of a sedimentary column to reproduce the formation of barite using the numerical simulation method. The results show that the original equilibrium of barite was broken by the cold seep fluids and Ba2+ was carried upward to the sulfate-rich zone leading to the formation of barite front. When there is no flux of methane from the bottom of sediment, the barite front disappears. The relationship between methane leakage flux and authigenic minerals was also discussed. It can be concluded that high methane flux corresponds to a shallow barite front in the sediment, furthermore, the barite content first increases and then decreases as the methane flux increases. At the same time, an inverse relationship between the ratio of authigenic barite to calcite and methane flux was obtained.

Experimental and Numerical Simulation of the Formation of Cold Seep Carbonates in Marine Sediments

“…The simulation was performed by TOUGHREACT, which is a numerical simulation tool for non-isothermal flow chemical reactions of multiphase fluids in pores and fractured media [24]. Some studies have used TOUGHREACT to investigate AOM and carbonate precipitation in cold seep areas [18,25,26]. A brief introduction of the numerical simulation process is provided below, and for details, readers should see the TOUGHREACT Handbook [24,27].…”

Geochemical and Geophysical Monitoring of Hydrocarbon Seepage in the Adriatic Sea

“…In particular, seeps can be associated to metal-bearing deposits of commercial interest, such as Fe-Mn oxyhydroxide and carbonates. Precipitation in sub-surface sediments leads to quantitative adsorption of dissolved rare earth elements (REE) from the fluid plume and enrichments in the surrounding sediments [47] and accumulation of baryte [48,49], which has been recently added to the list of critical raw materials for the EU. Furthermore, specific microbial communities are indicative of the presence of hydrocarbons in the seabed sediments and microbial prospecting has been used for decades for petroleum exploration [50].…”