Experimental Simulation of the Formation of Fibrous Veins by Localised Dissolution-Precipitation Creep

Paul D. Bons and Mark W. Jessell
Department of Earth Sciences, Monash University, Clayton, VIC 3168, Australia

Abstract: Fibrous veins are generally interpreted in terms of the crack-seal mechanism. Several aspects of fibrous veins (fibrous structure, curved fibres, symmetry of antitaxial veins) are however better explained by vein formation without fracturing. Mass transfer to such veins would be by diffusional transport rather than by fluid flow through the veins. Deformation by dissolution-precipitation creep can provide the driving force for the necessary mass transfer. Veins form when mass transfer is heterogeneous and precipitation is localised.

Experiments were performed which enforced a chemical potential gradient, acting as the driving force for diffusional mass transfer. These experiments resulted in fibrous growths in aggregates of soluble salts (NaCl and KCl) saturated with brine. The experimental results support the theory that fibrous veins may form without fracturing and that rather than providing evidence for major fluid pathways, fibrous veins may instead represent localised precipitation during diffusional material transfer.

Keywords: fibrous veins • dissolution-precipitation creep • mass transfer • deformation

Mineralogical Magazine; February 1997 v. 61; no. 404; p. 53-63; DOI: 10.1180/minmag.1997.061.404.06
© 1997, The Mineralogical Society
Mineralogical Society (www.minersoc.org)