3-D numerical modelling of the influence of pre-existing faults and boundary conditions on the distribution of deformation: Example of North-Western Ghana

Feng, Xiaoting; Amponsah, Prince Ofori; Martin, Roland; Ganne, Jérôme; Jessell, Mark

doi:10.1016/j.precamres.2015.06.006

Cited by 17 publications

(7 citation statements)

References 129 publications

(157 reference statements)

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“…In this paper, we apply convergent velocity boundary conditions at a rate of 2.5 mm/year on either side. The base of the model domain is free slip, a free re-meshing boundary condition is applied to the model surface to produce relief [44,47]. For the thermal conditions of the model, we model the compression of a "hot" lithosphere.…”

Section: Numerical Methods and Model Setupmentioning

confidence: 99%

Role of Volcano-Sedimentary Basins in the Formation of Greenstone-Granitoid Belts in the West African Craton: A Numerical Model

et al. 2018

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Greenstone belts in the West African Craton (WAC) are separated by several generations of granitoids intruded at ca. 2.18-1.98 Ga. Simultaneous folding and exhumation play an important role in the formation of greenstone-granitoid belts. However, the overall tectonic regime and origin of granitoids remain controversial. In this study, we present the estimates of the mantle potential temperature (Tp) for the WAC, which yields values of about 1500-1600 • C, pressure estimates of initial and final melting yield values of about 3.7-5.2 GPa and 1-1.3 GPa, respectively. Subsequently, 2D thermo-mechanical models have been constructed to explore the width of volcano-sedimentary basin on spatial-temporal evolution of diapirs that emplaced in the lower-middle crust during compression. The models show that the width of the volcano-sediment layer plays an important role in the formation mechanisms of greenstone-granitoid belts. The lower crust beneath sedimentary sequences is deformed into a buckle fold during the first compressional stage, through which relief uplifts slowly. Subsequently, the buckle fold is further deformed into several individual folds. Diapirs made of lower crust rocks ascend and emplace in the middle-upper crust resulting from instability. Benefitting from the mantle temperature, the pressure estimates and the numerical modelling results, a new geodynamic model was constructed. This model indicates that a series of sheet-like granitoids possibly derived from either subducted mélanges, lower crust and/or mantle melting that are accumulated at depths of the subcontinental mantle would channel along diapirs before feeding the upper crust. When the granitoids arrive at the solidified lids of the diapirs, they would favour migrating horizontally and intrude into the upper crust through weakening zones between the diapirs. Our geodynamic model also suggests an asymmetry of structures between the upper and middle-lower crust, with the dome-like granitoids overlying high-grade sedimentary synforms and high-grade diapirs underlying low-grade greenstone belts.

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Section: Numerical Methods and Model Setupmentioning

confidence: 99%

Role of Volcano-Sedimentary Basins in the Formation of Greenstone-Granitoid Belts in the West African Craton: A Numerical Model

et al. 2018

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“…At a crustal scale, the processes of faulting and lower crust exhumation both play an important role in shaping surface relief (D'Agostino et al, 1998;Feng et al, 2016a). In an extensional setting ( Figures 5A1 and 5B1), the relay zone between faults in case A1 shows a subsidence of about 1-1.5km, while in case B1 it shows about 2km of uplift at 0.85Ma.…”

Section: Surface Reliefmentioning

confidence: 97%

“…In particular, the variation in the distribution of the Moho depth resulting from the D1 compression stage was not taken into 25 considerations for modelling. That could be interesting if we can perform a continuous process for the Sefwi terrane by including the D1 crustal thickening (Feng et al, 2016a) and the D2 transtension triggering the regional exhumation. In addition, we aim to involve more geophysical and geochemical constrains to improve the model setup (e.g., geochronological data; more P-T paths; distribution of Moho depth; thickness of the lithosphere and the mantle potential temperature during the Eburnean Orogeny etc.).…”

Section: Limitations and Perspectives 10mentioning

confidence: 99%

“…The bottom of the model is modelled with a free-slip boundary. The surface of the model is a free surface and its boundary thus directly corresponds to the topography (Moresi et al, 2003;Feng et al, 2016a). To balance the volume reduction due to applied extension rate, the upper mantle is allowed to flow in with a normal velocity during 25 extension/transtension (Liao and Gerya, 2014;Ganne et al, 2014).…”

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3D numerical modelling of the re-distribution of partially molten lower crust rocks in relay zones between faults during transtension: Implications for the Sefwi terrane, SW Ghana

Feng

Wang

Ganne

et al. 2018

Preprint

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Abstract. High-grade tectono-metamorphic domains in the Sefwi terrane of Ghana are separated from adjacent low-grade greenstone belts by two main shear zones. The high-grade rocks are thought to have been exhumed along sinistral shear zones during the D2 ENE-WSW transtension. To better understand the role boundary conditions and the spatial relationship of faults play in the re-distribution of partially molten lower crust, ten 3D thermo-mechanical models have been constructed.The results show that the normal component of velocity boundary conditions mainly controls the exhumation of the lower 15 crust which occurred along pre-existing faults, while the exhumation in the relay zones between faults is controlled by the ratio of extension rate to shear rate applied at the boundaries. The strike of the exhumation belt made of partially molten lower crust rocks in the relay zone is sub-orthogonal to the transtension direction. The isostatic compensation from lowdensity upper mantle to overlying crust (thinning) is higher under transtension than under extension. 20The lower crust exhumation influenced by inherited shear zones can be used to better understand the loci of the high-grade rocks in the Sefwi terrane. We suggest that the Kukuom-Juaboso domain composed of up to amphibolite-migmatite facies probably resulted from the concentration of partially molten rocks in the relay zone between the Ketesso and Kenyase shear zones during the D2 ENE-WSW transtension. The two shear zones probably underwent two main stages for growth and maturation from the D1 to D2 deformation phases. The regional exhumation of the high-grade rocks in the Sefwi terrane 25 probably occurred within a duration of less than 5Ma.

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“…In recent years, many scholars have studied the dynamic response of structural planes under the action of explosive stress waves. Kang et al [9] carried out ground stress measurement work on fault areas and found that the regional stress field is closely related to the faults' distribution characteristics [10][11][12][13][14][15][16]. Sebastian and Sitharam [17] used FLAC 3D simulation to study the attenuation law of stress wave propagation at the frictional structural plane and discussed the influence of joint parameters on the energy attenuation of stress waves.…”

Section: Introductionmentioning

confidence: 99%

Explosion‐Induced Stress Wave Propagation in Interacting Fault System: Numerical Modeling and Implications for Chaoyang Coal Mine

Feng

Zhang

Ali

2019

Shock and Vibration

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Exploring the propagation of stress waves in rocks with preexisting discontinuities is of great importance to reveal rock and geological engineering problems, particularly dynamic disasters like earthquakes and rockbursts in underground coal mining. In this paper, six 3D models established with COMSOL Multiphysics are employed to explore the influence of two preexisting faults with different orientations on the propagation process of explosion-induced stress waves and the reflection effect. Considering the propagation process of stress waves, the interactive effect between two different size faults is discussed. The results show that the dip angles of the preexisting fault and the differences of the elastic modulus, density, and Poisson’s ratio between faults and rocks have great influence on the distribution of stresses and strain-energy density. Immediately after the stress wave induced by blasting arrived at preexisting fault A, a relatively high concentration of the strain-energy density was observed at the last wave before passing through fault A. The presence of faults leads to the reflection of most of the blast energy. When the stress wave propagates across fault A, the strain energy stored in the stress wave becomes attenuated; thus, most strain energy was absorbed by the fault’s domain. Finally, the modeling results were implicated in Chaoyang Coal Mine to account for the distribution of the observed seismic events. This study has guiding significance for the attenuation law of stress waves passing through joint/fissure zones in geological engineering, earthquake engineering, and underground mining engineering.

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3-D numerical modelling of the influence of pre-existing faults and boundary conditions on the distribution of deformation: Example of North-Western Ghana

Cited by 17 publications

References 129 publications

Role of Volcano-Sedimentary Basins in the Formation of Greenstone-Granitoid Belts in the West African Craton: A Numerical Model

Role of Volcano-Sedimentary Basins in the Formation of Greenstone-Granitoid Belts in the West African Craton: A Numerical Model

3D numerical modelling of the re-distribution of partially molten lower crust rocks in relay zones between faults during transtension: Implications for the Sefwi terrane, SW Ghana

Explosion‐Induced Stress Wave Propagation in Interacting Fault System: Numerical Modeling and Implications for Chaoyang Coal Mine

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