Rationale for GIMS-15
Gas in Marine Sediments, from coastal to deep-water environments, has increasingly become an outstanding scientific topic for multiple reasons. Obviously, methane and other low molecular weight hydrocarbons represent an important energy resource. Naturally occurring gas also affects the physical properties and engineering behaviour of marine sediment.. Increasingly, submarine methane has become a discussion issue regarding past and future climate. This includes gas hydrates, which are abundant on modern Earth and might exist on other Solar System bodies and exoplanets. Seafloor methane emissions also feed chemosynthetic communities on the seafloor. Indeed, such gas-related marine habitats have been discovered in the Gulf of Cádiz and are now under protection.
Gas is generated, transported and stored in marine sediments through several mechanisms. Vast areas of continental margins across Earth host methane produced by microbial reactions involving organic compounds. However, in numerous regions, thermogenic and abiotic processes produce methane as well as other hydrocarbons. In many locations, methane in marine sediment occurs in at least two of three phases -dissolved, hydrate and free gas. But transport between these phases can involve slow diffusion, rapid advection, and other pathways depending on geological context. This variance is highlighted along the complex continental margins of Spain.
Release and consumption of gas from the seafloor also varies. In many locations, it occurs through aerobic and anaerobic oxidation of methane and the conversion of gas to bicarbonate via sulphate reduction. However, it also can be expelled (catastrophically or progressively) at the seafloor, triggered by several factors that include earthquakes, magma-intrusion, submarine landslides or fluctuations in sea level and ocean temperature. The Gulf of Cádiz is one the most important locations to study these processes. Here, scores of mud volcanoes have formed by the eruption of gas-enriched sediments associated with tectonic compression between the Eurasian and African plates, which also triggered giant tsunamis that impacted Portugal and Spain (including Cádiz) in 1755.
Furthermore, the fate of marine gas, through anaerobic oxidation of methane or venting, forces new perspectives across the scientific community. Of relevance to climate change, large excess amounts of greenhouse gases like methane or CO2 could be transferred to the atmosphere from the oceans. Of relevance to biology, Archaea, an ancient life form on Earth, plays an important role generating and consuming methane, in the latter case anaerobic oxidation of methane, which leads to carbonate precipitation within the sediment and at the seafloor. In this way, microbial-mediated formation of large amounts of methane-derived authigenic carbonates ties into the global cycling of carbon, sulphur, calcium and magnesium.
Established and novel marine technology to identify expressions of gas and gas seepage continue to improve considerably. There have been significant advances in 3D high-resolution seismic, AUVs/ROVs using ultra-high resolution multibeam bathymetry, and the development and installation of seafloor monitoring, such as cabled observatories.
Similar to past and successful GIMS meetings, GIMS15 will be a relatively small meeting (100-200 participants), at which a wide range of results and ideas can be shared and discussed in an engaging atmosphere by senior and early career scientists and those new to this exciting field.
We chose to hold the conference in Cádiz for two primary reasons: it is a focal point of current international studies on gas in marine sediment; it is a beautiful town located between the Atlantic Ocean and Mediterranean Sea, between Europe and Africa, and with a long, diverse, and complex history. It is a perfect warm and kind location to foster new and exciting research into gas in marine sediments. We are open to ideas and suggestions, and hope that you can attend.
The conference will be hosted by the Marine Science Faculty of the University of Cádiz and the Geological Survey of Spain. We include some basic information about the meeting below and invite you to visit the conference website.