Bas den Brok
Selected experimental projects until November 2004:
Effect of elastic strain on dissolution and growth microstructures on very soluble salts (K-alum, sodium chlorate, KDP) (DFG financed PhD study of J. Morel) [abstract]. Literature: (i) S.W.J. den Brok, J. Morel (2001) The effect of elastic strain on the microstructure of free surfaces of stressed minerals in contact with an aqueous solution. Geophysical Research Letters 28 (4), 603-606 [view at publisher]. (ii) J. Morel and S.W.J. den Brok (2001) Increase in dissolution rate of sodium chlorate induced by elastic strain. Journal of Crystal Growth 222, 637-644 [view at publisher].
Temperature-driven fibre growth in wet salt aggregates (part of diploma thesis M. Sieber) [abstract]. Literature: S.W.J. den Brok, C.W. Passchier, M. Sieber (1998) Fibre growth in wet salt aggregates in a temperature gradient field. Mineralogical Magazine 62 (4), 527-532 View at CiteSeerX.
Pressure solution compaction of sodium chlorate aggregates (part of diploma thesis M. Zahid) || [abstract]. Literature: S.W.J. den Brok, M. Zahid, C.W. Passchier (1999) Pressure solution compaction of NaClO3 and implications for pressure solution in NaCl. Tectonophysics 307, pp. 297-312 doi:10.1016/S0040-1951(99)00103-1
In-situ microscopic study of microcracking in wet sodium chlorate single
crystals (part of diploma thesis M. Zahid) || [abstract].
Literature: S.W.J. den Brok, M. Zahid, C.W. Passchier (1998) Cataclastic solution creep
of very soluble brittle salt as a rock analogue. Earth and Planetary
Science Letters 163, 83-95
In-situ microscopy study of ductile shear zone development by cataclastic solution creep in sodium chlorate aggregates (DFG financed PhD study of M. Zahid) [abstract] [abstract-2].
Pressure solution indentation experiments on K-alum single crystals (diploma thesis of G. Melisa) [abstract] || [abstract2-html] [pdf] We indented potassium alum single crystals with metal pistons in the presence of saturated potassium alum solution. In these experiments the indentation is driven by a chemical reaction rather than by stress. The pistons oxidise in the weakly acid alum solution. Pistons were coated at the side and could only react at the contact with the alum. Indentation rate appeared to be inversed proportional to the stress. Our experiments show that chemical reactions may drive deformation, leading to a very different mechanical behaviour where stress would play an only minor role.
Thin sections of natural fibrous gypsum veins (crossed polarisers). Note "static" recrystallisation of fibrous aggregate in right two pictures. Samples from Ober-Ehrendingen, Aargau.
Examples of experimentally recrystallised natural quartzite (left two pictures) and natural single crystals of quartz (right two pictures).
Quarz grain approximately 0.5 mm in size deformed by pressure solution
from above and below, and broken in parts. Fractures were filled in with
fibrous chlorite aggregate. The quartz fragments were slightly rotated.
Example from Olympic Mountains, Washington State.
4 November 2004