1,721,042 research outputs found
Impact of ephemeral cataclastic fabrics on laser diffraction particle size distribution analysis in loose carbonate fault breccia. Journal of Structural Geology
No full textPartile size distributions by laser diffraction: sensitivity of granular matter strength to analytical operating procedures.
No full textGrain size and permeability evolution of soft-sediment extensional sub-seismic and seismic fault zones in high-porosity sediments from the Crotone basin, southern Apennines, Italy.
No full textImpact of ephemeral cataclastic fabrics on laser diffraction particle size distribution analysis in loose carbonate fault breccia.
No full textSize-dependent comminution, tectonic mixing, and sealing behaviour of a “structurally oversimplifies” fault zone in poorly lithified sands: Evidence for a coseismic rupture?
No full textFRAP: a numerical tool to predict failure and deformation conditions along fault surfaces.
No full textFaults show strongly variable lateral permeability, largely dependent from the variability of amount of deformation along them. Several well-exposed examples confirm the difficulty in the task of predicting fault permeability. The development of fault deformation zones and fault cores, including fault gauge and cataclastic bands, is a function of several variables, including rock rheology, stress and strength conditions along the fault surface, fluid pressures, and the fault kinematics. Once you know the appropriate boundary conditions, analytical equations allow to compute an index of fault gauge formation at any point, as well as the geometry and type of expected (brittle) deformations. Due to the variability of the aforementioned values, a critical parameter is the displacement (amount and path) on the fault surface. This was be numerically integrated to properly predict the zones where higher deformation is expected. These computations were included in the FRAP numerical tool, including multiple event and multiple fault settings. External structural data can also be integrated in the computation, allowing to properly tune the prediction. Examples of applications includes the study of the variation of fault permeability in geothermal environment, as well as the modelling of the expected permeability in a grid of extensional faults in oil reservoirs
Predicting pre- and post-failure stress conditions and deformation patterns in fault zones by the FRAP numerical tool
No full textFaults show strongly variable lateral permeability, largely dependent from the variability of amount of deformation along them. Several well-exposed examples confirm the difficulty in the task of predicting fault permeability. The development of fault deformation zones and fault cores, including fault gauge and cataclastic bands, is a function of several variables, including rock rheology, stress and strength conditions along the fault surface, fluid pressures, and the fault kinematics. Once you know the appropriate boundary conditions, analytical equations allow to compute an index of fault gauge formation at any point, as well as the geometry and type of expected (brittle) deformations. Due to the variability of the aforementioned values, a critical parameter is the displacement (amount and path) on the fault surface. This was be numerically integrated to properly predict the zones where higher deformation is expected. These computations were included in the FRAP numerical tool, including multiple event and multiple fault settings. External structural data can also be integrated in the computation, allowing to properly tune the prediction. Examples of applications includes the study of the variation of fault permeability in geothermal environment, as well as the modelling of the expected permeability in a grid of extensional faults in oil reservoirs
Geological map of the partially dolomitized Jurassic succession exposed in the core of the Montagna dei Fiori Anticline, Central Apennines, Italy
No full textIn this contribution, we present a new geological map of the Jurassic formations exposed in the central sector of the Montagna dei Fiori anticline, in the Central Apennines. Mapping activity was devoted to better detail the extensional fault patterns still preserved in the anticlinal core and to separate dolostones from the parent limestones. The results of our work indicate that the lower half of the Corniola Fm. is systematically dolomitized in the study area. On the other hand, the underlying Calcare Massiccio Fm. is strongly dolomitized in the Castel Manfrino and Osso Caprino hill area, whereas limestone dominates to the east and to the south. Our new map supports block faulting induced by Jurassic rifting as the cause of the Calcare Massiccio Fm. map pattern, rather than gravity-driven block collapse, as alternatively proposed
Physical and chemical strain-hardening during faulting in poorly lithified sandstone: The role of kinematic stress field and selective cementation
Full text linkIn this work, we report the results of a multidisciplinary study describing the structural architecture and diagenetic evolution of the Rocca di Neto extensional fault zone developed in poorly lithified sandstones of the Crotone Basin, Southern Italy. The studied fault zone has an estimated displacement of ∼90 m and consists of: (1) a low-deformation
zone with subsidiary faults and widely spaced deformation bands; (2) an ∼10-mwide damage zone, characterized by a dense network of conjugate deformation bands; (3) an ∼3-m-wide mixed zone produced by tectonic mixing of sediments with different grain size; (4) an ∼1-m-wide fault core with bedding transposed into foliation and ultracomminute black gouge layers. Microstructural investigations indicate that particulate flow was the dominant early-stage deformation mechanism, while cataclasis became predominant after porosity loss, shallow burial, and selective calcite cementation. The combination of tectonic compaction and preferential cementation led to a strain-hardening behavior inducing the formation of “inclined conjugate deformation band sets” inside the damage zone, caused by the kinematic stress field associated with fault activity. Conversely, conjugate deformation band sets with a vertical bisector formed outside the damage zone in response to the regional extensional stress field. Stable isotope
analysis helped in constraining the diagenetic environment of deformation, which is characterized by mixed marine-meteoric signature for cements hosted inside the damage zone, while it progressively becomes more meteoric moving outside the fault zone. This evidence supports the outward propagation of fault-related deformation structures in the
footwall damage zone
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