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

Abstract

Cold seep emissions of low temperature fluid from the marine sediment basins are mainly comprised of methane and other hydrocarbons. A series of biogeochemical processes related to methane lead to the formation of authigenic carbonate minerals. In this study, a self-built experimental device was used to study the formation process of carbonate minerals under cold seep conditions. The concentrations of pore water chemicals, HCO3− and Ca2+ at different heights of the reactor under flow conditions can be observed. According to the experimental results, the formation process of carbonate minerals under cold seep conditions was estimated, that 1 m carbonate growth needs 12,000 and 7000 years, respectively, under fast (5 mL·min−1) and slow emission (1 mL·min−1) conditions. Furthermore, TOUGHREACT was used to simulate the diagenesis process. A 1D unsteady react-transport model was developed, and the experimental data was used to constrain the simulation. The results of simulation show that the carbonates need 17,000 and 9700 years to grow 1 m under the condition of fast and slow flow scenarios, respectively. The results of this work will contribute to the study of foundation on the formation of authigenic minerals in cold seep areas, and for the physical properties of sedimentary media as well.

Laboratory Experimental Study on the Formation of Authigenic Carbonates Induced by Microbes in Marine Sediments

“…The laboratory experiment related to authigenic carbonates, some study the formation duration of carbonate minerals under cold seep conditions [17], and some study the relationship between biominerals and the microbes [18]. However, there are few researches on the formation mechanism of carbonate minerals in marine sediments.…”

New cold seep sites on the continental slope southwest to Svalbard

“…The structure A found at about 820 m depth in SK01 is the first of its kind to be observed on the western Svalbard continental margin. The presence of more than 80 cm thick methane-derived authigenic carbonate crusts near the centre of the structure suggests a relatively long seepage history of at least several thousand years (Ye et al, 2019), similar to what it was documented from both theVestnesa Ridge (Himmler et al, 2019) and the southwestern Barents Sea (Crémière et al, 2016). This is further supported by the presence of a glacigenic debris flow stopping nearby the acoustic blanking corridor below the structure A covered by several metres of postglacial sediments (Figure 11).…”