Evidence of evaporite deposition in the Lower Carboniferous Main Limestone Series of South Wales,U.K.

Petrographic examination of the dolomitized Main Limestone Series cropping out in the south, east and northeast corners of the South Wales Coalfield Basin shows evidence of the earlier presence of evaporite minerals. However, it is believed that lack of extensive evaporite deposits in these rocks may be due to the active diagenetic dissolution and oncoming humid coal conditions of post Main Limestone time.The evaporite minerals in the Main Limestone rocks seem to be overwhelmingly early diagenetic in origin in the light of the following observations: (1) calcite or dolomite pseudomorphs after gypsum crystals associated with a fine pelmicrite matrix; (2) association of such pseudomorphs with oolitic pelsparite; and (3) evaporite solution breccia texture.