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The major features of many sedimentary basins can be understood in terms either of lithospheric stretching or of tectonic loading of the lithosphere. These models allow broad predictions to be made concerning the thermal evolution and the hydrocarbon-maturation histories of the basins in question.
In any particular basin, however, the conductive temperature structure is liable to be modified significantly by the convective transport of heat by circulating pore fluids. Even very slow flows that are too small to be detected during drilling or by conventional hydrologic techniques may have a significant influence if they persist over long periods. Such flows have been demonstrated in the North Sea and the Alberta basin and may operate over a depth of several kilometers and have horizontal dimensions of tens of kilometers.
Much remains to be learned about the causes and behavior of circulations of this kind. By disturbing the conductive distribution of temperature, they delay the maturation of hydrocarbons in some areas and accelerate it in others. They may influence the migration of hydrocarbons, both directly and indirectly, through modification of the permeability structure by solution and precipitation. It is not possible to interpret the fine structure of sedimentary basins and the distribution of hydrocarbons within them without an understanding of these processes.
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