The main structural element governing the morphology, hydrology and hydrogeology of Jordan is the Dead Sea Rift fault Zone. It trends nearly N-S and forms an active part of the African-Syrian Rift, which extends from east Africa through the Red Sea, Dead Sea to south Turkey. Sedimentary rocks cover almost the whole area of Jordan and have been subdivided into two major aquifers complex: upper and lower aquifers separated by more or less an impermeable sequence of marl and marly limestone of the Upper Cretaceous age. The upper aquifer complex consists of limestone, chert, and marly limestone of the Upper Cretaceous, while the lower aquifer complex consists mainly of sandstones of Lower Cretaceous and older ages. The geothermal activity in Jordan is expressed entirely in the form of thermal springs. Other geothermal phenomena such as fumarolic activity and boiling mud pools or altered ground are not found. The location of nearly all thermal springs and anomalously thermal wells is dictated by their proximity to the Dead Sea Rift. Generally, they are distributed along a distance of about 200km on the eastern side of the Rift and discharge their water from the lower aquifer complex. The Zara-Zarqa Ma'in thermal springs are considered as the major geothermal manifestation in Jordan due to its high temperatures and flow rates. The heat source of the thermal water in the lower aquifer is a result of the deep circulation of water within the Paleozoic sandstones receiving heat from a normal to slightly elevated geothermal gradient. Away from the Rift in Jiza region, many wells were drilled to the upper aquifer complex and discharge thermal water with temperatures up to 46°C. The dense faults net of the different trends in this area, strongly suggested that the two-aquifer systems are hydraulically connected. This allows the thermal water from the lower aquifer to flow up via faults (conduits) into the upper aquifer raising the groundwater temperature in the vicinity of these faults. Thermal water sources in Jordan belong to low enthalpy geothermal sources, therefore, power generation is unlikely to be possible but they are quite suitable for direct uses such as; Spas, fish farming, space heating for selected constructions and other direct uses.
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