Thermal History
Foreland basins are considered to be hypothermal basins (cooler than normal), with low geothermal gradient and heat flow. Heat flow values average between 1 and 2 HFU (40-90 mWm−2 (Allen & Allen 2005). Rapid subsidence may be responsible for these low values.
Over time sedimentary layers become buried and lose porosity. This can be due to sediment compaction or the physical or chemical changes, such as pressure or cementation. Thermal maturation of sediments is a factor of temperature and time and occurs at shallower depths due to past heat redistribution of migrating brines.
Vitrinite reflectance, which typically demonstrates an exponential evolution of organic matter as a function of time, is the best organic indicator for thermal maturation. Studies have shown that present day thermal measurements of heat flow and geothermal gradients closely correspond to a regime’s tectonic origin and development as well as the lithospheric mechanics (Allen & Allen 2005).
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