Projects per year
Abstract
Host rock mechanical heterogeneities influence the spatial distribution of deformation structures and hence, predictions of fault architecture and fluid flow. A critical factor, commonly overlooked, is how rock mechanical properties can vary over time, and how this will alter deformation processes and resultant structures. We present field data from an area in the Borborema Province, NE Brazil, that demonstrate how temporal changes in deformation conditions, and consequently processes, exerts a primary control on the spatial distribution and geometric attributes of evolving deformation structures. Further, each temporal deformation phase imparted different hydraulic architecture. The earliest flowing structures localized upon subtle ductile heterogeneities. Following fault formation, both fault core and damage zone were flow conduits. In later stages of faulting pseudotachylyte welding created a low-permeability fault core and annealed high-permeability fractures within the fault damage zone. Modern flow occurs along a zone of later open shear fractures, defined by the mechanical strength contrast between the host rock and annealed fault. This second hydraulically-conductive zone extends 100s of meters from the edge of the annealed fault damage zone, creating a flow zone far wider than would be predicted using traditional fault scaling relationships. Our results demonstrate the importance of understanding successive deformation events for predicting the temporal and spatial evolution of hydraulically active fractures.
Original language | English |
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Pages (from-to) | 509-524 |
Number of pages | 16 |
Journal | Journal of the Geological Society |
Volume | 171 |
Issue number | 4 |
Early online date | 28 Apr 2014 |
DOIs | |
Publication status | Published - Jul 2014 |
Keywords
- crustal structure
- deformation
- fault zone
- heterogeneity
- host rock
- hydraulic conductivity
- hydraulic fracture
- pseudotachylite
- rock mechanics
- spatial distribution
- temporal evolution
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Dive into the research topics of 'Brittle structures focused on subtle crustal heterogeneities: implications for flow in fractured rocks'. Together they form a unique fingerprint.Profiles
Projects
- 1 Finished
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THE SIMULTANEOUS EVOLUTION OF SEISMICITY AND PERMEABILITY WITHIN GEOLOGICAL FAULTS
Lunn, R. (Principal Investigator)
NERC (Natural Environment Research Council)
1/02/07 → 2/12/10
Project: Research
Research output
- 20 Citations
- 4 Article
-
Scale-dependent influence of pre-existing basement shear zones on rift faulting: a case study from NE Brazil
Kirkpatrick, J., Bezerra, H., Shipton, Z., do Nascimento, A., Pytharouli, S., Lunn, R. & Soden, A., Mar 2013, In: Journal of the Geological Society. 170, 2, p. 237 –247 11 p.Research output: Contribution to journal › Article › peer-review
File48 Citations (Scopus)248 Downloads (Pure) -
Microseismicity illuminates open fractures in the shallow crust
Pytharouli, S., Lunn, R., Shipton, Z., Kirkpatrick, J. & do Nascimento, A., 29 Jan 2011, In: Geophysical Research Letters. 38, 5 p., L02402.Research output: Contribution to journal › Article › peer-review
25 Citations (Scopus) -
Modeling the heterogeneous hydraulic properties of faults using constraints from reservoir-induced seismicity
Nascimento, A., Lunn, R. J. & Cowie, P., 2005, In: Journal of Geophysical Research Atmospheres. 110, B09201Research output: Contribution to journal › Article › peer-review
33 Citations (Scopus)