Strike‐slip reactivation of segmented normal faults: Implications for basin structure and fluid flow

Rotevatn, Atle; Peacock, David

doi:10.1111/bre.12303

Cited by 27 publications

(14 citation statements)

References 92 publications

(147 reference statements)

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“…Tectonics Peacock, 2018). The presence of a left-lateral component along the SAFS would be in agreement with the few focal mechanisms recorded in the area.…”

Section: 1029/2020tc006116supporting

confidence: 85%

Active Extension in a Foreland Trapped Between Two Contractional Chains: The South Apulia Fault System (SAFS)

et al. 2020

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The response of continental forelands to subduction and collision is a widely investigated topic in geodynamics. The deformation occurring within a foreland shared by two opposite‐verging chains, however, is uncommon and poorly understood. The Apulia Swell in the southern end of the Adria microplate (Africa‐Europe plate boundary, central Mediterranean Sea) represents one of these cases, as it is the common foreland of the SW verging Albanides‐Hellenides and the NE verging Southern Apennines merging into the SSE verging Calabrian Arc. We investigated the internal deformation of the Apulia Swell using multiscale geophysical data: multichannel seismic profiles recording up to 12‐s two‐way time (TWT) for a consistent image of the upper crust; high‐resolution multichannel seismic profiles, high‐resolution multibeam bathymetry, and CHIRP profiles acquired by R/V OGS Explora to constrain the Quaternary geological record. The results of our analyses characterize the geometry of the South Apulia Fault System (SAFS), a 100‐km‐long and 12‐km‐wide structure attesting an extensional (and possibly transtensional) response of the foreland to the two contractional fronts. The SAFS consists of two NW‐SE right‐stepping master faults and several secondary structures. The SAFS activity spans from the Early Pleistocene through the Holocene, as testified by the bathymetric and high‐resolution seismic data, with long‐term slip rates in the range of 0.2–0.4 mm/yr. Considering the position within an area with few or none other active faults in the surroundings, the dimension, and the activity rates, the SAFS can be a candidate causative fault of the 20 February 1743, M 6.7, earthquake.

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“…Tectonics Peacock, 2018). The presence of a left-lateral component along the SAFS would be in agreement with the few focal mechanisms recorded in the area.…”

Section: 1029/2020tc006116supporting

confidence: 85%

Active Extension in a Foreland Trapped Between Two Contractional Chains: The South Apulia Fault System (SAFS)

et al. 2020

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“…Secondly, the reactivated relay zones may represent local structural highs along strike, which means that such locations are associated with structural trap formation where fluids, such as hydrocarbons, may potentially accumulate (cf. Fossen et al, 2010).…”

Section: Implications For Fluid Flow In Sedimentary Basinsmentioning

confidence: 99%

Strike-slip reactivation of segmented normal faults: implications for basin structure and fluid flow

Rotevatn¹,

Peacock²

2018

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Reverse reactivation of normal faults, also termed ‘inversion’, has been extensively studied, whereas little is known about the strike-slip reactivation of normal faults. At the same time, recognizing strike-slip reactivation of normal faults in sedimentary basins is critical, as it may alter and impact basin physiography, accommodation and sediment supply and dispersal. Motivated by this, we present a study of a reactivated normal fault zone in the Liassic limestones and shales of Somerset, UK, to elucidate the effects of strike-slip reactivation of normal faults, and the inherent deformation of relay zones that separate the original normal fault segments. The fault zone, initially extensional, exhibits a series of relay zones between right-stepping segments, with the steps between the segments having subsequently become contractional due to sinistral strike-slip movement. The relay zones have therefore been steepened and are cut by a series of connecting faults with reverse and strike-slip components. The studied fault zone, and comparison with larger-scale natural examples, lead us to conclude that the relays-turned-contractional-steps are associated with (i) complex fault and fracture networks that accommodate shortening, (ii) anomalously high numbers of fractures and faults, (iii) layer parallel slip and (iv) folding and uplift. Comparison with published statistics from global relay zones shows that whereas the reactivated relay zones feature aspect ratios similar to those of unreactivated relay zones, bed dips within reactivated relay zones are significantly steeper than unreactivated relay zones. Given the potential of reactivated relay zones to form areas of local uplift, they may affect basin structure and may also form potential traps for hydrocarbon or other fluids. The elevated faulting and fracturing, on the other hand, means reactivated relays are also likely loci for enhanced up-fault flow.

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“…The relay ramp deformed once again as an area of localized extension, enhancing its fracturing. Favorable conditions for the rise of deep‐seated fluids generally occur in relay ramps or interaction zones as established in global geothermal and oil fields (e.g., Faulds et al, 2013; Fossen & Rotevatn, 2016; Rotevatn & Peacock, 2018; Rowland & Sibson, 2004). The local extension of the SVFS relay ramp develops a Hill‐type mixed extensional/shear‐extensional fracture mesh composed of NNE‐SSW, ESE‐WNW, and NW‐SE trending, high‐angle faults, and fractures (Pola et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Fault Control on a Thermal Anomaly: Conceptual and Numerical Modeling of a Low‐Temperature Geothermal System in the Southern Alps Foreland Basin (NE Italy)

et al. 2020

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The interest on low‐temperature geothermal resources is progressively increasing since their renewability and widespread availability. Despite their frequency, these resources and their development have been only partially investigated. This paper unravels the major physical processes driving a low‐temperature geothermal resource in NE Italy (Euganean Geothermal System) through conceptual and numerical modeling. Dense fracturing associated to regional fault zones and a relay ramp enhances regional to local flow of thermal waters. Their rapid upwelling in the Euganean Geothermal Field is favored by open extensional fractures deforming the relay ramp. The water (65–86 °C) is intensively exploited for balneotherapy, rendering it a profitable resource. Three‐dimensional coupled flow and heat transport numerical simulations based on this conceptual model are performed. Despite the presence of a uniform basal heat flow, a thermal anomaly corresponding to field observations develops in the modeling domain reproducing the relay ramp. Intensive fracturing extending across a wide area and a slightly anomalous heat flow favors a local increase in convection that drives the upwelling of deep‐seated hot waters. The simulations corroborate and refine the conceptual model, revealing that water of up to 115 °C is likely to be found in the unexplored part of the thermal field. This study furthers knowledge on fault‐controlled low‐temperature geothermal resources where the geological setting could enhance local convection without anomalous heat flows, creating temperatures favorable for energy production. Conceptual and numerical modeling based on solid geological and hydrogeological reconstructions can offer a support tool for further detailed explorations of these prominent resources.

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Strike‐slip reactivation of segmented normal faults: Implications for basin structure and fluid flow

Cited by 27 publications

References 92 publications

Active Extension in a Foreland Trapped Between Two Contractional Chains: The South Apulia Fault System (SAFS)

Active Extension in a Foreland Trapped Between Two Contractional Chains: The South Apulia Fault System (SAFS)

Strike-slip reactivation of segmented normal faults: implications for basin structure and fluid flow

Fault Control on a Thermal Anomaly: Conceptual and Numerical Modeling of a Low‐Temperature Geothermal System in the Southern Alps Foreland Basin (NE Italy)

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