The role of a heterogeneous inclusion during continental collision

Vilotte, J. P.; Daignières, M.; Madariaga, R.; Zienkiewicz, O. C.

doi:10.1016/0031-9201(84)90049-9

Cited by 65 publications

(55 citation statements)

References 6 publications

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“…Already in the early 80s, Molnar and Tapponnier (1981) proposed that variations in the thermal structure, controlled by the age of the last orogenic episode affecting the crust, might explain the heterogeneous strain distribution in Asia in response to the India collision. This hypothesis was corroborated by numerical models, which showed that an older and stiffer block embedded in a collision zone, such as the Tarim block in the Himalayas, remains roughly undeformed and produces strain localization around it (Vilotte et al, 1984;England and Houseman, 1985). A similar process may explain why fossil Meso-and Neoproterozoic orogenic belts and the active East African rift wrap around the Tanzanian craton in eastern Africa (Fig.…”

Section: Thermal Heterogeneitymentioning

confidence: 68%

Heterogeneity and anisotropy in the lithospheric mantle

2015

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International audienceThe lithospheric mantle is intrinsically heterogeneous and anisotropic. These two properties govern the repartition of deformation, controlling intraplate strain localization and development of new plate boundaries. Geophysical and geological observations provide clues on the types, ranges, and characteristic length scales of heterogeneity and anisotropy in the lithospheric mantle. Seismic tomography points to variations in geothermal gradient and hence in rheological behavior at scales of hundreds of km. Seismic anisotropy data substantiate anisotropic physical properties consistent at scales of tens to hundreds of km. Receiver functions imply lateral and vertical heterogeneity at scales < 10 km, which might record gradients in composition or anisotropy. Observations on naturally deformed peridotites establish that compositional heterogeneity and Crystal Preferred Orientations (CPOs) are ubiquitous from the mm to the km scales. These data allow discussing the processes that produce/destroy heterogeneity and anisotropy and constraining the time scales over which they are active. This analysis highlights: (i) the role of deformation and reactive percolation of melts and fluids in producing compositional and structural heterogeneity and the feedbacks between these processes, (ii) the weak mechanical effect of mineralogical variations, and (iii) the low volumes of fine-grained microstructures and difficulty to preserve them. In contrast, olivine CPO and the resulting anisotropy of mechanical and thermal properties are only modified by deformation. Based on this analysis, we propose that strain localization at the plate scale is, at first order, controlled by large-scale variations in thermal structure and in CPO-induced anisotropy. In cold parts of the lithospheric mantle , grain size reduction may contribute to strain localization, but the low volume of fine-grained domains limits this effect

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Section: Thermal Heterogeneitymentioning

confidence: 68%

Heterogeneity and anisotropy in the lithospheric mantle

2015

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“…Observing that these blocks have not deformed significantly since the India-Asia collision, whereas younger domains were extensively deformed, Molnar and Tapponnier (1981) first suggested a dependence of the intensity and style of active tectonics on the age of the last orogenic activity in Asia, and hence on the strength contrast between the various terranes that compose the Eurasian plate. Numerical models simulating the role of the Tarim shield during the India-Eurasia collision (Vilotte et al, 1984;England and Houseman, 1985) indicate that stiff inclusions within a continental plate submitted to compression induce stress concentration at their edges or tips, that favour strain localization and initiation of shear zones in the surrounding material, whereas the stiff domains tend to behave as rigid blocks and remain almost undeformed.…”

Section: Development Of Stiff Heterogeneities: Aging Of the Continentmentioning

confidence: 99%

Rheological heterogeneity, mechanical anisotropy and deformation of the continental lithosphere

1998

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This paper aims to present an overview on the influence of rheological heterogeneity and mechanical anisotropy on the deformation of continents. After briefly recapping the concept of rheological stratification of the lithosphere, we discuss two specific issues: (1) as supported by a growing body of geophysical and geological observations, crust=mantle mechanical coupling is usually efficient, especially beneath major transcurrent faults which probably crosscut the lithosphere and root within the sublithospheric mantle; and (2) in most geodynamic environments, mechanical properties of the mantle govern the tectonic behaviour of the lithosphere. Lateral rheological heterogeneity of the continental lithosphere may result from various sources, with variations in geothermal gradient being the principal one. The oldest domains of continents, the cratonic nuclei, are characterized by a relatively cold, thick, and consequently stiff lithosphere. On the other hand, rifting may also modify the thermal structure of the lithosphere. Depending on the relative stretching of the crust and upper mantle, a stiff or a weak heterogeneity may develop. Observations from rift domains suggest that rifting usually results in a larger thinning of the lithospheric mantle than of the crust, and therefore tends to generate a weak heterogeneity. Numerical models show that during continental collision, the presence of both stiff and weak rheological heterogeneities significantly influences the large-scale deformation of the continental lithosphere. They especially favour the development of lithospheric-scale strike-slip faults, which allow strain to be transferred between the heterogeneities. An heterogeneous strain partition occurs: cratons largely escape deformation, and strain tends to localize within or at the boundary of the rift basins provided compressional deformation starts before the thermal heterogeneity induced by rifting are compensated. Seismic and electrical conductivity anisotropies consistently point towards the existence of a coherent fabric in the lithospheric mantle beneath continental domains. Analysis of naturally deformed peridotites, experimental deformations and numerical simulations suggest that this fabric is developed during orogenic events and subsequently frozen in the lithospheric mantle. Because the mechanical properties of single-crystal olivine are anisotropic, i.e. dependent on the orientation of the applied forces relative to the dominant slip systems, a pervasive fabric frozen in the mantle may induce a significant mechanical anisotropy of the whole lithospheric mantle. It is suggested that this mechanical anisotropy is the source of the so-called tectonic inheritance, i.e. the systematic reactivation of ancient tectonic directions; it may especially explain preferential rift propagation and continental break-up along pre-existing orogenic belts. Thus, the deformation of continents during orogenic events results from a trade-off between tectonic forces applied at plate boundaries, plate geometry,...

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“…In recognition of the importance of intraplate orogeny as an expression of continental rejuvenation, a large amount of work has focused on the mechanisms leading to large-scale intraplate failure (e.g. Vilotte et al 1982;England & Houseman 1985;Kuzsnir & Park 1987;England & Jackson 1989;Platt & England 1994;Tommasi et al 1995;Ziegler et al 1995Ziegler et al , 1998Avouac & Burov 1996;Neil & Houseman 1997;Sandiford & Hand 1998;Hand & Sandiford 1999;Pysklywec et al 2000).…”

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confidence: 99%