Porosity changes induced by salt weathering of sandstones, Bohemian Cretaceous Basin, Czech Republic

Title:

Porosity changes induced by salt weathering of sandstones, Bohemian Cretaceous Basin, Czech Republic

Creator:

Jiří Adamovič, Mikuláš, Radek, Böhmová, Vlasta, and Jana Schweigstillová

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:21c862a4-9570-466c-9a1b-8ba5ec68ac39
uuid:21c862a4-9570-466c-9a1b-8ba5ec68ac39
issn:1214-9705

Subject:

Geologie. Meteorologie. Klimatologie, pórovitost, pískovce, porosity, sandstones, honeycombs, rock crust, salt weathering, case hardening, 7, and 551

Type:

article, články, model:article, and TEXT

Format:

print, bez média, and svazek

Description:

Different types of rock crusts and the underlying unweathered sandstone were sampled in the Bohemian Cretaceous Basin, Czech Republic. Structure and mineral composition of the samples were studied using optical microscopy, scanning electron microscopy with EDAX, and X-ray diffraction. Pore parameters were determined using mercury intrusion porosimetry/ helium pycnometry. Principal salts identified in the rock crusts and in the efflorescences are gypsum and alums. Two types of rock crusts were distinguished on morphological basis: 1. patterned rock crusts with a variety of weathering forms (honeycombs, wandkarren), and 2. armoured rock crusts with a relatively smooth, hardened layer. Patterned rock crusts on medium- to coarse-grained quartzose sandstones show an increase in the size of macropores relative to unweathered sandstone, which mostly implies an increase in total effective porosity. This is explained by the subflorescent growth of salt crystals, the force of which leads to the loss of contact among grains, pore widening, and granular disintegration. Armoured rock crusts on fine-grained clayey sandstone show a reduced volume and size of macropores, as these are filled with clay mineral aggregates and gypsum crystals. A prominent increase in the volume of micropores is due to secondary porosity in kaolinite and corrosion of feldspar grains. Insufficient passability of macropores in the armoured layer for pore waters shifts the evaporation front deeper into the rock. This results in contour scaling as the main process of rock-surface degradation, as opposed to granular disintegration on patterned rock crusts., Jiří Adamovič, Radek Mikuláš, Jana Schweigstillová and Vlasta Böhmová., and Obsahuje bibliografii

Language:

English

Rights:

http://creativecommons.org/licenses/by-nc-sa/4.0/
policy:public

Source:

Acta geodynamica et geomaterialia : | 2011 Volume:8 | Number:1 (161)

Harvested from:

CDK

Metadata only:

false