Fluid flow is fundamental to many geological processes, including the development of natural resources of hydrocarbons, ore deposits and water. Modelling of these processes requires information on the timing of fluid flow events and the interaction of fluids with surrounding rocks. In addition to isotopic methods, a diversity of approaches has been developed to assess the timing of events, including palaeomagnetism, fission track analysis and fluid inclusion studies. Many techniques also provide information on the duration of fluid flow events. The papers in this volume represent the range of approaches available to determine the dating and duration of fluid flow events and fluid-rock interaction: first overview of methods of dating fluid flow; examples of commercial application of dating methods; explanations of methodology suitable for advanced teaching; extensive bibliographies.

Frontiers in Geofluids is a collection of invited papers chosen to highlight recent developments in our understanding of geological fluids in different parts of the Earth, and published to mark the first ten years of publication of the journal Geofluids. The scope of the volume ranges from the fundamental properties of fluids and the phase relationships of fluids encountered in nature, to case studies of the role of fluids in natural processes. New developments in analytical and theoretical approaches to understanding fluid compositions, fluid properties, and geological fluid dynamics across a wide range of environments are included. A recurrent theme of research published in Geofluids is the way in which similar approaches can be applied to geological fluids in very different settings and this is reflected in the diverse range of applications of fluid studies that are included here. They include deep groundwater flow, hydrocarbons in faulted sedimentary basins, hydrothermal ores, and multiphase flow in mid-ocean ridge systems. Other topics covered are geothermal waters, crustal metamorphism, and fluids in magmatic systems. The book will be of great interest to researchers and students interested in crustal and mantle fluids of all sorts.

The hydrodynamics of a mature sedimentary basin affected by uplift, deposition, and erosion is examined in the Palo Duro Basin, Texas, with a cross-sectional ground-water flow model. Transient simulations of ground-water flow assuming uniform fluid density are used to describe hydrodynamic conditions arising from changes in topography. Modeling shows that uplift and tilting of the basin (10 to 15 m.y. ago) caused significant increase in ground-water flow rates. Erosion of the Pecos River valley and the more recent westward retreat of the Caprock Escarpment cause significant hydraulic-head changes in deep aquifer units within the last few million years. Buoyancy effects on regional ground-water flow through the Palo Duro Basin where densities range between 1.00 and 1.15 g/cm3 are studied using a new modeling technique, based on equivalent fresh-water heads and stream functions, incorporating fluid densities that vary in space but are assumed to be time invariant. Flow velocities based on the stream-function solution were found to be more accurate than those based on the head solution, allowing a more accurate interpretation of local flow patterns. Simulated streamlines show that the regional groundwater flow in the vertical plane is not significantly affected by density variations, indicating that the topographically-driven flow component dominates potential buoyancy phenomena. However, equivalent freshwater heads differ from those obtained assuming fresh-water density, which has important implications on model calibration. Paleohydrologic modeling indicates that prior to basin uplift, when the topographically induced head gradients were smaller than at present, buoyancy phenomena can produce stationary convection cells in the western part of the basin, characterized by stratified density distribution. Another convection cell is simulated in the eastern part, where density within the deep aquifer decreases with depth creating thermohaline convection. Potential effects of regional ground-water flow on thermal regime, suggested by the thermal gradient pattern, were studied by simulating energy transport associated with heat flow from the basement and advection through ground water. Simulation results suggest that the thermal regime is dominated by conduction. Advection is probably insignificant due to large anisotropy of the hydrostratigraphic units, relatively shallow depth of the flow system, and large ratio of basin width to basin depth.