Analysis of transpression within contractional fault steps using finite-element method

Nabavi, Seyed Tohid; Alavi, Seyed Ahmad Naseri; Mohammadi, Soheil; Glodny, Johannes; Frehner, Marcel

doi:10.1016/j.jsg.2017.01.004

Cited by 25 publications

(13 citation statements)

References 110 publications

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“…The modeling results of the absolute values of stress and displacements are uncertain but instead show a relative pattern. The physical properties of the rocks in the study area have not been tested before, and their values used here are from the previous study using FEM to model stresses in a general case (Table 1; Nabavi et al, 2017).…”

Section: Finite Element Methodsmentioning

confidence: 99%

Gas Emissions in a Transtensile Regime Along the Western Slope of the Mid-Okinawa Trough

Cai

et al. 2021

Front. Earth Sci.

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Gas emissions from the seabed are favored by tectonically active settings and their distribution is often linked to the nearby faults. Here we use the multi-beam echo-sounder (MBES) and the multi-channel seismic (MCS) data and a sediment core to show multiple gas emissions near the fault complex out of the shelf of the Mid-Okinawa Trough. The features indicating the gas emissions include 1) a set of the conical positive reliefs at the seabed, 2) the bundle-shaped clusters of the high-backscattering intensities in the water column, and 3) the sub-circular medium-to high-backscattering patches at the level of the seabed. These features together show that the free gases can escape from the marine sediments then rise in the water column at present, while some other gases trapped in the sub-seafloor sediment might contribute to the precipitation of the authigenic carbonates in the past. The spatial relationship between the gas emissions and the faults suggests that the faulting driven by the back-arc extension should provide the permeable migration pathways for the gas emissions to operate, and thus determines where most of them could potentially occur. The area surrounding the restraining bend concentrates part of the gas emissions rather than along the fault lines, due to the lateral compression and the structural complexity. This is demonstrated by the results of the numerical model of finite element method (FEM), which shows two gas emissions are within the compressed zone of the modeled restraining step-over. This study provides new evidence of the role of the tectonic stresses in determining the sites of degassing of marine sediments.

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Section: Finite Element Methodsmentioning

confidence: 99%

Gas Emissions in a Transtensile Regime Along the Western Slope of the Mid-Okinawa Trough

Cai

et al. 2021

Front. Earth Sci.

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“…Irregularities of the fault trace are common for strike-slip faults, and may arise from the evolution of disconnected faults over time, compositional heterogeneity or fault interaction, among others, (e.g., Mann, 2007). If step-overs or bends are present along a fault, strike-slip motion has to deal with these obstacles, and local deformation will deviate from simple shear by a component of shortening or extension (Fossen and Tikoff, 1998;McClay and Bonora, 2001;Nabavi et al, 2017). Transtensional settings develop around fault releasing bends and extensional step overs, which occur where the sense of fault slip and the sense of the fault offset are the same, like for a right-stepping pull apart on a right-lateral fault.…”

Section: Introductionmentioning

confidence: 99%

Slip Partitioning in the 2016 Alboran Sea Earthquake Sequence (Western Mediterranean)

et al. 2020

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A M W 5.1 earthquake on January 21st, 2016 marked the beginning of a significant seismic sequence in the southern Alboran Sea, culminating in a M W 6.3 earthquake on January 25th, and continuing with further moderate magnitude earthquakes until March. We use data from 35 seismic broadband stations in Spain, Morocco and Portugal to relocate the seismicity, estimate seismic moment tensors, and isolate regional apparent source time functions for the main earthquake. Relocation and regional moment tensor inversion consistently yield very shallow depths for the majority of events. We obtain 50 moment tensors for the sequence, showing a mixture of strike-slip faulting for the foreshock and the main event and reverse faulting for the major aftershocks. The leading role of reverse focal mechanisms among the aftershocks may be explained by the geometry of the fault network. The mainshock nucleates at a bend along the left-lateral Al-Idrisi fault, introducing local transpression within the transtensional Alboran Basin. The shallow depths of the 2016 Alboran Sea earthquakes may favor slip-partitioning on the involved faults. Apparent source durations for the main event suggest a ∼21 km long, asymmetric rupture that propagates primarily toward NE into the restraining fault segment, with fast rupture speed of ∼3.0 km/s. Consistently, the inversion for laterally variable fault displacement situates the main slip in the restraining segment. The partitioning into strikeslip rupture and dip-slip aftershocks confirms a non-optimal orientation of this segment, and suggests that the 2016 event settled a slip deficit from previous ruptures that could not propagate into the stronger restraining segment.

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“…In this regard, the study of transpression (and transtension) zones helps us to better understand crustal 3D kinematics, as deduced from many field-based studies (e.g., Díaz-Azpiroz and Fern� andez, 2005;Zanchi et al, 2016;Nabavi et al, 2017bNabavi et al, , 2017cSimonetti et al, 2018;Bergh et al, 2019;Alonso-Henar et al, 2020), as well as analytical (e.g., Fossen et al, 1994;Fossen and Tikoff, 1998;Jones et al, 2004;Jiang, 2007;Fern� andez and Díaz-Azpiroz, 2009;Díaz-Azpiroz et al, 2019) (Fig. 1), analogue (e.g., Tikoff and Peterson, 1998;Casas et al, 2001;Leever et al, 2011;Ghosh et al, 2014;Barcos et al, 2016;Sadeghi et al, 2016), and numerical (e.g., Davis et al, 2013;Nevitt et al, 2014Nevitt et al, , 2017Dasgupta et al, 2015;Frehner, 2016;Nabavi et al, 2017aNabavi et al, , 2018aNabavi et al, , 2018bNabavi et al, , 2019 models. In essentially ductile transpressional zones both simple shearing and coaxial flow are commonly present within the entire shear zone producing complex finite deformation geometries (e.g., Alsop et al, 1998;Mazzoli, 2008, 2015;Davis and Titus, 2011;Fern� andez et al, 2013;Fossen and Cavalcante, 2017;Carreras and Druguet, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, most oblique convergence settings are horizontally and vertically heterogeneous in their constitutive properties, which affect the structural style and deformation mechanics. Therefore, the structural style and fault systems patterns in natural transpressive (or transtensional) zones are controlled, in addition to the convergence angle, by the orientation of the mechanical layering with respect to the strain field, the relative orientation of pre-existing faults, and the coefficient of sliding friction on the fault plane (Bott, 1959;Hughes et al, 2014;Hughes and Shaw, 2015;Ferrill et al, 2017;Nabavi et al, 2017aNabavi et al, , 2018a. Mechanical stratigraphy causes non-uniform deformation of multilayer systems when subjected to tectonic stress (e.g., Treagus, 1993;Gomez-Rivas and Griera, 2012).…”

Section: Introductionmentioning

confidence: 99%

Deformation mechanics in inclined, brittle-ductile transpression zones: Insights from 3D finite element modelling

Nabavi

Alavi

Azpiroz

et al. 2020

Journal of Structural Geology

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Analysis of transpression within contractional fault steps using finite-element method

Cited by 25 publications

References 110 publications

Gas Emissions in a Transtensile Regime Along the Western Slope of the Mid-Okinawa Trough

Gas Emissions in a Transtensile Regime Along the Western Slope of the Mid-Okinawa Trough

Slip Partitioning in the 2016 Alboran Sea Earthquake Sequence (Western Mediterranean)

Deformation mechanics in inclined, brittle-ductile transpression zones: Insights from 3D finite element modelling

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