Aproximación a los primeros efectos de la meteorización en una dolomía (Fm. Gijón, Asturias)

Resumen

Effects of initial weathering in a Jurassic dolomite are investigated from a petrographic and petrophysical viewpoint. The selected samples of ‘intact rock’, taken in several outcrops across the Gijón-Villaviciosa Basin (Asturias), correspond to four lithotypes with common textural and mineralogical features but representing different stages of weathering. In all sam- ples, however, the rock keeps a massive appearance. The effects of weathering translate mainly as compositional changes, variation of elementary physical properties and a differentiated mechanical behavior that have been assessed by laboratory tests. The color of the rock changes from gray to yellowish tones and there is a noticeable increase in porosity, which exceeds five times what corresponds to the unaltered rock. This results in the consequent decrease in bulk density and a significant loss of mechanical strength under point load tests, being almost an order of magnitude lower than that of fresh rock.