The Flushing of Saline Groundwater from a Permo-Triassic Sandstone Aquifer System in NW England

摘要

Using geological, hydrochemical, and geophysical data, a conceptual model is developed in order to explain the occurrence and distribution of saline groundwater in a Permo-Triassic sandstone sequence in northwest England. The saline water is derived from fresh water dissolution of halite, probably sometime prior to the Tertiary. Uplift in the Tertiary lead to erosion which eventually exposed the sandstones, and flushing of the saline water by fresh water commenced. The geometry of the system, and the presence of low permeability faulls reduces the flushing efficiency so that saline groundwater exists everywhere in the lower parts of the sandstone body, and even in the upper parts in places. Upconing on a regional scale has also occurred, probably since the end of the Devensian, and flushing is actively occurring.