Distribution of secondary minerals in crusts developed on sandstone exposures

Auteur(s) et Affiliation(s)



Description :
This study considers the surfaces of sandstone tors in the Polish Outer Carpathians. The exposed parts of the rocks in this area are often covered by crust, which is up to several centimetres thick, and differs from the internal part in colour and composition. The crusts were characterized using light and electron microscopy, X-ray diffractometry, thermal analyses, Mössbauer spectroscopy, bulk chemical analyses and sequential chemical extractions. Porosity was estimated by digital image processing. Development of the crust results from silicon and iron redistribution during the sandstone alteration. Hematite is probably a result of goethite transformation. However, air pollutants may play an important role in the formation of sulphates. Silica and iron compounds affect the properties of the rock, hardening the surface and lowering porosity by formation of secondary cement. Crystallization of sulphate salts, in turn, may contribute to mechanical disintegration of the rock.


Type de document :
Article de périodique

Source :
Earth surface processes and landforms, issn : 0197-9337, 2014, vol. 39, n°. 3, p. 320-335, nombre de pages : 16, Références bibliographiques : 2 p.

Date :
2014

Editeur :
Pays édition : Royaume-Uni, Chichester, Wiley