EDITORIAL Frontiers in geofluids: editorial This special double issue of Geofluids marks both the tenth anniversary of the launch of the journal and the first vol- ume to appear only online. Geofluids has truly tracked a fundamental change in the nature of scientific publication. For this issue, we sought to bring together a collection of papers spanning a range of topics to which the role of flu- ids in the Earth is central. Geofluids was founded to help emphasise the common ground between fluid processes that take place in different geological settings, and to pro- vide an outlet for research that considers the interactions of chemical and physical processes. While we cannot pre- tend to provide a comprehensive coverage of all the impor- tant recent advances, we are delighted to have been able to bring together some excellent and wide-ranging new sci- ence that continues in this tradition. The first four articles all concern our fundamental theo- retical and experimental understanding of essentially aque- ous fluids. Liebscher provides an overview of the properties of water-rich fluid systems and how these are affected by solutes, while noting the remaining limitations in the experimental database. Dolejs and Manning present the first comprehensive study to produce a more flexible alter- native to the HKF model for aqueous electrolytes, better suited to the range of compositions and conditions encountered in nature, while Sherman shows how modern computational power means that some fundamental prob- lems in natural fluid chemistry can be addressed from first principles using quantum chemistry and molecular dynam- ics. In the final article in this section, Newton and Man- ning review recent experimental results for lower crustal conditions and present new data to quantify the impor- tance of dissolved salts for the solubility of the major rock –forming elements, Si and Al, and for a range of important Ca-minerals. The second group of articles relate to a specific geologi- cal setting where fluid processes are of the highest impor- tance: sedimentary basins. Parnell provides a concise review of the use of hydrocarbon fluid inclusions to understand the evolution of reservoirs through time and the relation- ships between fluid stages and mineral cements. He shows in particular how this approach has contributed to under- standing the oil charge history of the North Sea and UK Atlantic margin. Hanor and Mercer describe the behaviour of saline waters and their distribution in the Gulf of Mexico, and show how salinity differences arising through salt dissolution can dictate flow patterns. They also explore the likely impacts of salt on the potential of the region as a source of methane hydrates. The article by Manzocchi, Childs and Walsh reviews how faults affect the flow of fluids, in particular hydrocarbons, in siliciclastic basins, and also comment on the extent to which current industry practice for evaluating the effects of faults is actu- ally grounded in science. A third group of article deals with fluid processes in oce- anic settings. Saffer has modelled the lateral variations along the Nankai margin of Japan and shown that large scale variations along strike in the taper angle of the accre- tionary wedge can be linked back to lithological variations from more turbidite-rich sequences to mudrocks. The lithology affects the development of fluid overpressure and the draining of the subduction zone fault, which in turn influences the overall geometry of the wedge. The interplay between permeability, heat flow and discharge characteris- tics at mid-ocean ridges is explored by Driesner. His results support some findings from terrestrial geothermal systems: high temperature discharges, and the highest fluid salini- ties, may be associated with low fluid fluxes, while large discharges at relatively low temperatures may in fact domi- nate the removal of heat. Fisher and Harris take three spe- cific examples of mid-ocean ridge settings to explore the controls on heat loss. The relative importance of conduc- tive heat loss is variable, and specific features of the base- ment geology can serve to target fluid flow and hence heat loss. Hydrothermal vents are also of likely significance for both abiotic and metabolic organosynthesis and this is explored by Shock and Canovas. Different patterns of mix- ing of seawater with different hydrothermal fluids can lead to different evolutionary paths, but in general, the mixing favours formation of organic compounds from inorganic reactants. Hence, microbes could produce components of biomolecules simply by catalysis of reactions that are already energetically favoured. A fourth group of articles deals with the continental crust. Ingebritsen and Manning present a crustal-scale overview of permeability and argue that while there is a power–law relation between permeability and depth in tec- tonically active continental crust, some regions exhibit markedly higher permeabilities, probably as transients, while stable crust may decay to lower permeability. The specific issue of the relationship of hydrologic response to Geofluids (2010) 10, 1–2 doi: 10.1111/j.1468-8123.2010.00290.x Ó 2010 Blackwell Publishing Ltd