Experimental studies of marine gas hydrate geochemical anomalies

Abstract

Geochemical exploration of marine gas hydrate based on the geochemical anomalies (e.g., ion concentrations in pore water and isotope in water and gas) caused by the formation/dissociation processes of marine gas hydrate. Geochemists are very interested in determining whether the ion concentration change seen in seawater as a result of hydrate formation can be observed at laboratory timescales. To solve this problem, we have designed a simple but efficient experimental device and developed the experimental techniques and methods for measuring gas hydrate geochemical anomalies. The concentrations of ions and isotopes are measured before and after an experiment so that the variations of ion and isotope in water can be estimated in a sediment-seawater-methane system. The fractionation coefficients of H and O isotopes have been also calculated in this system. Thus, a qualitative and quantitative understanding of how ion concentrations change under different formation conditions has been preliminarily established.