Lopez T., Antoine R., Darrozes J., Rabinowicz M., Baratoux David. (2018). Development and evolution of the size of polygonal fracture systems during fluid-solid separation in clay-rich deposits. Journal of Earth Science, 29 (6), p. 1319-1334. ISSN 1674-487X.
Titre du document
Development and evolution of the size of polygonal fracture systems during fluid-solid separation in clay-rich deposits
Lopez T., Antoine R., Darrozes J., Rabinowicz M., Baratoux David
Source
Journal of Earth Science, 2018,
29 (6), p. 1319-1334 ISSN 1674-487X
In continental and oceanic conditions, clay-rich deposits are characterised by the development of polygonal fracture systems (PFS). PFS can increase the vertical permeability of clay-rich deposits (mean permeability 10(-16) m(2)) and are pathways for fluids. On continents, the width of PFS ranges from centimeters to hundreds of meters, while in oceanic contexts they are up to a few kilometres large. These structures are linked to water-solid separation during deposition, consolidation and complete fluid squeeze of the clay horizon. During the last few decades, modeling of melt migration in partially molten plastic rocks led to rigorous quantifications of two-phase flows with a particular emphasis on 2D and 3D induced flow structures. The numerical modeling shows that the melt migrates on distances at most equal to a few times the compaction length L that depends on permeability and viscosity. Consequently, polygonal structures in partially molten plastic rocks result from the melt-rock separation and their sizes are proportional to L. Applying these results to fluid-solid separation in clay-rich horizons, we show that (1) centimetric to kilometric PFS result from the dramatic increase of L during compaction and (2), this process involve agglomerates with 100 m to 1 mm size.
Plan de classement
Sciences fondamentales / Techniques d'analyse et de recherche [020]
;
Géologie et formations superficielles [064]
