Depositional environment and diagenesis as controlling factors for petro-physical properties and weathering resistance of siliciclastic dimension stones: integrative case study on the ‘Wesersandstein’ (northern Germany, Middle Buntsandstein)

Abstract

Abstract A case study on the ‘Wesersandstein’ (Middle Buntsandstein) indicates that weathering resistance and quality of dimension stones are functions of depositional environment, and of diagenetic alterations (eogenetic as well as mesogenetic) during geological history. Two types of dimension stones, one deposited in a braided and the other in a meandering river system, were compared with respect to the fluvial architecture, the diagenetic modifications, the raw block prospectivity, and the petro-physical properties. The integrative synthesis of all these approaches indicates that depositional environment (type of fluvial architecture) and diagenesis (quartz cement and clay matrix contents) are the key processes which generally control the petro-physical properties and the weathering resistance of siliciclastic dimension stones. The highly quartz cemented ‘Grauer Wesersandstein’ with low clay matrix content, deposited as channel fill (braided river system), is characterized in general as a high quality dimension stone with very good petro-physical properties (e.g. high compressive strength, tensional strength, abrasion resistance, and freeze-thaw resistance) and high weathering resistance. In contrast to this, the ‘Roter Wesersandstein’, deposited as point bar and floodplain deposits of meandering rivers with low quartz cement and high clay matrix contents shows minor quality petro-physical properties (e.g. minor compressive strength, tensional strength, abrasion resistance, and freeze-thaw resistance) and weathering resistance. This new integrative approach combines hitherto isolated studies on dimension stone quality. It shows the complex interrelations between the geological background on the one hand and specific dimension stone properties on the other hand.