Evolution of fault patterns within a zone of pre-existing pervasive anisotropy during two successive phases of extensions: an experimental study

Ghosh, Nilabja; Hatui, Kalyanbrata; Chattopadhyay, Anupam

doi:10.1007/s00367-019-00627-6

Cited by 9 publications

(9 citation statements)

References 54 publications

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“…Our data show that the border faults are oblique to the extension direction, and accommodate a major (80 -75%) normal-and minor (20 -25%) shear-components of strain, indicating they are oblique-slip faults, rather than pure dip-slip. Similar oblique-slip sense on faults striking oblique to the extension direction has been interpreted qualitatively in previous analogue models (e.g., Withjack & Jamison, 1986;Tron & Brun, 1991;Corti et al, 2007;Agostini et al, 2009;Corti, 2012;Molnar et al, 2019;Ghosh et al, 2020). Surprisingly, the extension-orthogonal, en échelon internal structures in our oblique extension models are pure strike-slip, differing from the dip-slip (vertical displacement) interpreted in earlier analogue (e.g., Corti, 2008;Agostini et al, 2009;Philippon et al, 2015) and numerical models (e.g., Brune, 2014;Duclaux et al, 2020).…”

Section: Comparison With Previous Analogue and Numerical Modeling Studiessupporting

confidence: 82%

“…Scaled analogue or numerical models allow us to monitor the progressive crustal strain localization process and the development of rifts at high resolution in space and time. Over the past decades a growing number of analogue-(e.g., Withjack & Jamison, 1986;Allemand & Brun, 1991;Tron & Brun, 1991;Dauteuil & Brun, 1993;McClay & White, 1995;Bonini et al, 1997;Keep & McClay, 1997;Basile & Brun, 1999;Brun, 1999;Clifton et al, 2000;Michon & Merle, 2000;Corti et al, 2001;Chemenda et al, 2002;McClay et al, 2002;Bellahsen et al, 2003;Corti et al, 2003;Bellahsen & Daniel, 2005;Michon & Sokoutis, 2005;Sokoutis et al, 2007;Agostini et al, 2009;Autin et al, 2010;Henza et al, 2010;Aanyu & Koehn, 2011;Agostini et al, 2011;Autin et al, 2013;Chattopadhyay & Chakra, 2013;Tong et al, 2014;Bonini et al, 2015;Philippon et al, 2015;Zwaan et al, 2016;Zwaan & Schreurs, 2017;Molnar et al, 2019;Sani et al, 2019;Zwaan et al, 2019;Ghosh et al, 2020;Maestrelli et al, 2020;Molnar et al, 2020) and numerical-(e.g., Van Wijk, 2005;…”

Section: Insert Figurementioning

confidence: 99%

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Influence of zones of pre-existing crustal weakness on strain localization and partitioning during rifting: Insights from analogue modeling using high resolution 3D digital image correlation

Osagiede¹,

Rosenau²,

Rotevatn³

et al. 2022

Preprint

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The factors controlling the selective reactivation of pre-existing crustal structures and strain localization process in natural rifts have been studied for decades but remain poorly understood. We present the results of surface strain analysis of a series of analogue rifting experiments designed to test the influence of the size, orientation, depth, and geometry of pre-existing crustal weak zones on strain localization and partitioning. We apply distributed basal extension to crustal-scale models that consist of a silicone weak zone embedded in a quartz sand layer. We vary the size and orientation (θ-angle) of the weak zone with respect to the extension direction, reduce the thickness of the sand layer to simulate a shallow weak zone, and vary the geometry of the weak zone to reflect a range of anticlinal, either linear or curvilinear natural weak zone geometries. Our results show that at higher θ-angle (≤ 60o) both small- and large-scale weak zones localize strain into graben-bounding (oblique-) normal faults. At lower θ-angle (≤ 45o), small-scale weak zones do not localize strain effectively, unless they are shallow. We observe diffuse, second-order strike-slip internal graben structures, which are conjugate and antithetic under orthogonal and oblique extension, respectively. In general, the changing nature of the rift faults (from discrete fault planes to diffuse fault zones, from normal to oblique and strike-slip) highlights the sensitivity of rift architecture to the orientation, size, depth, and geometry of pre-existing weak zones. Our generic models are comparable to observations from many natural rift systems like the northern North Sea and East Africa, and thus have implications for understanding the role of structural inheritance in rift basins globally.

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Section: Comparison With Previous Analogue and Numerical Modeling Studiessupporting

confidence: 82%

Section: Insert Figurementioning

confidence: 99%

Influence of zones of pre-existing crustal weakness on strain localization and partitioning during rifting: Insights from analogue modeling using high resolution 3D digital image correlation

Osagiede¹,

Rosenau²,

Rotevatn³

et al. 2022

Preprint

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show abstract

“…This natural cohesion value of 12 MPa is slightly lower than cohesions measured in rock deformation labs (e.g. Handin, 1969;Jaeger and Cook, 1976;Twiss and Moore, 1992) but is acceptable, since in nature, the lithosphere is generally weakened by several phases of deformation. When assessing viscous materials, the Ramberg number R m applies (Weijermars and Schmeling, 1986): R m = gravitational stress / viscous strength = (ρ × g × h 2 )/(η × v).…”

Section: Scalingmentioning

confidence: 61%

Complex rift patterns, a result of interacting crustal and mantle weaknesses, or multiphase rifting? Insights from analogue models

et al. 2021

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Abstract. During lithospheric extension, localization of deformation often occurs along structural weaknesses inherited from previous tectonic phases. Such weaknesses may occur in both the crust and mantle, but the combined effects of these weaknesses on rift evolution remain poorly understood. Here we present a series of 3D brittle–viscous analogue models to test the interaction between differently oriented weaknesses located in the brittle upper crust and/or upper mantle. We find that crustal weaknesses usually express first at the surface, with the formation of grabens parallel to their orientation; then, structures parallel to the mantle weakness overprint them and often become dominant. Furthermore, the direction of extension exerts minimal control on rift trends when inherited weaknesses are present, which implies that present-day rift orientations are not always indicative of past extension directions. We also suggest that multiphase extension is not required to explain different structural orientations in natural rift systems. The degree of coupling between the mantle and upper crust affects the relative influence of the crustal and mantle weaknesses: low coupling enhances the influence of crustal weaknesses, whereas high coupling enhances the influence of mantle weaknesses. Such coupling may vary over time due to progressive thinning of the lower crustal layer, as well as due to variations in extension velocity. These findings provide a strong incentive to reassess the tectonic history of various natural examples.

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“…Many natural rift systems have been impacted by the reactivation of older shear zones, including the NE Brazilian margin (Kirkpatrick et al., 2013), offshore southern Norway (Phillips et al., 2016), the East African Rift System (Daly et al., 1989; Heilman et al., 2019), and the Australian Southern Margin (Gibson et al., 2013; Miller et al., 2002). At the scale of individual rift basins, reactivation of basement structures—including discrete faults (Bellahsen & Daniel, 2005; Bonini et al., 2015; Deng et al., 2017, 2018) and mechanically weak layers that make up a pervasive fabric (Chattopadhyay & Chakra, 2013; Ghosh et al., 2020)—during rifting can also influence the orientation, length, and kinematics of faults in the overlying sedimentary cover.…”

Section: Introductionmentioning

confidence: 99%

Inheritance of Penetrative Basement Anisotropies by Extension‐Oblique Faults: Insights From Analogue Experiments

et al. 2021

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Reactivation of weak surfaces (e.g., foliation planes) in metamorphic basement rocks facilitates the nucleation of new faults along such pre-existing surfaces (Byerlee, 1978;Sibson, 1985). Hence, basement reactivation gives rise to extension-oblique, rift-related faults that nucleate on basement weaknesses and inherit the strike and dip direction of the basement fabric (Collanega et al., 2019;Phillips et al., 2016;Rotevatn et al., 2018). As a consequence, the similarity in orientation between pre-existing basement structures and new rift faults has often been interpreted as evidence of basement-influenced rifting, involving reactivation of the aforementioned basement structures (

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Evolution of fault patterns within a zone of pre-existing pervasive anisotropy during two successive phases of extensions: an experimental study

Cited by 9 publications

References 54 publications

Influence of zones of pre-existing crustal weakness on strain localization and partitioning during rifting: Insights from analogue modeling using high resolution 3D digital image correlation

Influence of zones of pre-existing crustal weakness on strain localization and partitioning during rifting: Insights from analogue modeling using high resolution 3D digital image correlation

Complex rift patterns, a result of interacting crustal and mantle weaknesses, or multiphase rifting? Insights from analogue models

Inheritance of Penetrative Basement Anisotropies by Extension‐Oblique Faults: Insights From Analogue Experiments

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