Spatial correlation of fluid inclusion generations: reconstructing fluid flow during basin evolution

Fluid inclusion analysis is used to reconstruct the spatial and temporal va riation of fluid composition and thermal properties within the NE-German in tracontinental basin. Microthermometric and SEM-EDS analyses of fluid inclu sions allow the distinction of palaeo-fluid systems and show their lateral and vertical distribution and variation through time. Early fluids, migrati ng in the deeper parts of the basin, are characterised by complex salinitie s. Sulphur content of these fluids increases towards the contact with the Z echstein, suggesting a partial exchange with the evaporites. Coexisting flu ids, restricted to authigenic minerals in the Upper Carboniferous sediments and Rotliegend volcanics are dominated by NaCl, CaCl2 and KCl. Younger, se condary fluid inclusions, sometimes containing gas phases, indicate increas ing temperatures. Thermal properties of the fluid inclusions indicate steep thermal gradients below the base of the Zechstein and Rotliegend sediments . This is interpreted as documentation of convective or advective heat dow in the deeper parts of the basin, with the Zechstein salt as a seal to this convective system. (C) 2000 Elsevier Science B.V. All rights reserved.