Abstract
Deformation bands, usually recognized in association with faults, are here analyzed in relation to a tight synclinal fold developed in the Miocene Numidian turbidites of Sicily. Deposited above a growing thrust-wedge and then buckled during continued deformation, the porous Numidian sandstones form subsurface gas reservoirs elsewhere in the region and are analogues for deepwater systems in general. Structural data have been collected and statistically analyzed to characterize preferred orientations and size parameters (thickness, spacing, length) of deformation bands. Two distinct populations relate to folding: the most recent one is NE-SW oriented, which produced the most prominent structures, whereas an older one is partially obliterated. Microscopic investigation reveals porosity decreases within deformation bands with respect to host rock. The principal deformation mechanisms are grain rotation/sliding and pore-collapse, consistent with folding having occurred under low burial conditions. Within the thrust wedge, near-surface folding is widespread, as indicated by growth strata. Thus we expect early-burial deformation bands of the types (compaction an shear bands) illustrated here to be a component of reservoir damage in subsurface examples.
Original language | English |
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Pages (from-to) | 150-164 |
Number of pages | 15 |
Journal | Journal of Structural Geology |
Volume | 118 |
Early online date | 23 Oct 2018 |
DOIs | |
Publication status | Published - Jan 2019 |
Bibliographical note
We really appreciated the criticisms and valuable observations by two anonymous reviewers which improved significantly an early version of the manuscript. We are grateful to Prof. Kurt Mengel for availability to perform microanalysis with EPMA facility at TU Clausthal (Germany) and Totò Scalisi and the Major of Sperlinga village to permit access to the castle. SG acknowledges an Erasmus+ grant funded by the University of Catania. EF, RM and RP acknowledge a FIR 2014 CF093A grant fromthe University of Catania (Scientific Coordinator R. Maniscalco). EF, RP are thankful to Lucia Mancini for help and assistance during X-ray tomography acquisitions.
Keywords
- deformation bands
- Numidian sandstones
- porosity
- X-ray microtomography
- reservoir analogue
- Reservoir analogue
- Deformation bands
- Porosity