Petrophysical record of evolution of weakly deformed low-porosity limestone revealed by small-angle neutron scattering, neutron diffraction and AMS study

0494331 - GFÚ 2019 RIV GB eng J - Journal Article
Machek, Matěj - Kalvoda, L. - Hladil, Jindřich - Roxerová, Zuzana - Vratislav, S. - Drahokoupil, J. - Ryukhtin, Vasil
Petrophysical record of evolution of weakly deformed low-porosity limestone revealed by small-angle neutron scattering, neutron diffraction and AMS study.
Geophysical Journal International. Roč. 215, č. 2 (2018), s. 895-908. ISSN 0956-540X. E-ISSN 1365-246X
R&D Projects: GA ČR(CZ) GJ16-25486Y; GA ČR GB14-36566G; GA MŠMT LM2015056
Institutional support: RVO:67985530 ; RVO:67985831 ; RVO:61389005
Keywords : microstructure * permeability and porosity * magnetic fabrics and anisotropy * folds and folding
OECD category: Geology; Condensed matter physics (including formerly solid state physics, supercond.) (UJF-V); Geology (GLU-S)
Impact factor: 2.777, year: 2018

Rock physical and transport properties are affected by many rock features, such as texture, porosity, pore type, pore's shape preferred orientation and pore fluid. In carbonates, porosity and microstructure are complex issues resulting from a variety of depositional, diagenetic and deformation processes. To be able to correctly interpret physical properties of carbonate rocks, it is advantageous to combine studies of rock structure, texture and pore space. The combination of structural analysis, microstructure characterization and anisotropic physical properties evaluation successfully distinguished records of particular processes that formed complex microstructure of the Middle Devonian limestones of the Prague Synform in the Bohemian Massif. The primary sedimentary record is associated with carbonate bioclasts and lithoclasts marked by accessory minerals that have been recorded by the anisotropy of magnetic susceptibility method. The diagenetic stage consists of oriented authigenic quartz grains recognized by neutron diffraction. The weak calcite crystallographic preferred orientation has been interpreted as a result of vertical maximum compressive stress acting during the static recrystallization at the maximum burial stage. The small- and ultrasmall-angle neutron scattering measurements show that very low porosity (similar to 0.2 per cent) of the studied limestones is formed by preferentially oriented microcracks of 1.8-3.1 mu m in size. Their preferred orientation argues for the origin either during the maximum burial stage or at the latest stages of the first regional folding.
Permanent Link: http://hdl.handle.net/11104/0287555