Influence of geometry and eclogitization on oceanic plateau subduction

Arrial, P.; Billen, M. I.

doi:10.1016/j.epsl.2012.12.011

Cited by 81 publications

(84 citation statements)

References 53 publications

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“…3b-f). We propose that this is due to buoyancy imparted by the overthickened oceanic crust and harzburgite layer associated with the ridge, consistent with previous modelling studies 16 . Third, we observe that the modern inboard extent of the Peruvian flat slab corresponds to the location of the trench at about 10 Ma.…”

supporting

confidence: 72%

The role of ridges in the formation and longevity of flat slabs

Antonijevic

Wagner

Kumar

et al. 2015

Nature

106

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Flat-slab subduction occurs when the descending plate becomes horizontal at some depth before resuming its descent into the mantle. It is often proposed as a mechanism for the uplifting of deep crustal rocks ('thick-skinned' deformation) far from plate boundaries, and for causing unusual patterns of volcanism, as far back as the Proterozoic eon. For example, the formation of the expansive Rocky Mountains and the subsequent voluminous volcanism across much of the western USA has been attributed to a broad region of flat-slab subduction beneath North America that occurred during the Laramide orogeny (80-55 million years ago). Here we study the largest modern flat slab, located in Peru, to better understand the processes controlling the formation and extent of flat slabs. We present new data that indicate that the subducting Nazca Ridge is necessary for the development and continued support of the horizontal plate at a depth of about 90 kilometres. By combining constraints from Rayleigh wave phase velocities with improved earthquake locations, we find that the flat slab is shallowest along the ridge, while to the northwest of the ridge, the slab is sagging, tearing, and re-initiating normal subduction. On the basis of our observations, we propose a conceptual model for the temporal evolution of the Peruvian flat slab in which the flat slab forms because of the combined effects of trench retreat along the Peruvian plate boundary, suction, and ridge subduction. We find that while the ridge is necessary but not sufficient for the formation of the flat slab, its removal is sufficient for the flat slab to fail. This provides new constraints on our understanding of the processes controlling the beginning and end of the Laramide orogeny and other putative episodes of flat-slab subduction.

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supporting

confidence: 72%

The role of ridges in the formation and longevity of flat slabs

Antonijevic

Wagner

Kumar

et al. 2015

Nature

106

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“…Flat subduction and the subduction of ridges and aseismic ridges are pervasive today and through Earth's history (van Hunen et al, 2002;Arrial and Billen, 2013). The correlation between flat segments and subduction of aseismic ridges with thickened oceanic crust in South America bears this out (Gans et al, 2011;Bishop et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

“…The correlation between flat segments and subduction of aseismic ridges with thickened oceanic crust in South America bears this out (Gans et al, 2011;Bishop et al, 2013). The presence of thickened crust makes flat segments buoyant or neutrally buoyant (van Hunen et al, 2002;Arrial and Billen, 2013). Thickened crust is the result of higher degrees of partial melting, which result in crust that is drier than average MORB (Langmuir and Forsyth, 2007).…”

Section: Discussionmentioning

confidence: 99%

“…The net buoyancy 5 difference between normal and oceanic lithosphere with overthickened crust is largely determined by the thickness of the basaltic layer and that of the depleted harzburgitic mantle (c.f. Cembrano et al 2007, Arrial andBillen, 2013). From the crustal thicknesses and compositions across the Argentine and Peruvian flat-slab segments (~20 km, Gans et al, 2011;Bishop et al, 2013) and the Nazca ridge offshore (~17-18 km, Woods and Okal, 1994) To explore the time variation of dynamic topography, we also constructed a Paleocene-Early Miocene Nazca slab model (from here on referred to as the Paleogene model), in which the slab dips ~30˚ eastward homogeneously along strike, representative of the geometry of the Farallon and early Nazca slabs (Mpodozis and Ramos, 1989).…”

Section: Methodsmentioning

confidence: 99%

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Dynamic uplift during slab flattening

Dávila¹,

Lithgow‐Bertelloni²

2015

Earth and Planetary Science Letters

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Subduction exerts a strong control on surface topography and is the main cause of large vertical motions in continents, including past events of large-scale marine flooding and tilting. The mechanism is dynamic deflection: the sinking of dense subducted lithosphere gives rise to stresses that directly pull down the surface. Here we show that subduction does not always lead to downward deflections of the Earth's surface. Subduction of young lithosphere at shallow angles (flat subduction) leaves it neutrally or even positively buoyant with respect to underlying mantle because the lithosphere is relatively warm compared with older lithosphere, and because the thickened and hence drier oceanic crust does not undergo the transformation of basalt to denser eclogite. Accounting for neutrally buoyant flat segments along with large variations in slab morphology in the South American subduction zone explains alongstrike and temporal changes in dynamic topography observed in the geologic record since the beginning of the Cenozoic. Our results show that the transition from normal subduction to slab flattening generates dynamic uplift, preventing back-arc marine flooding.

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“…Arrial and Billen (2013) illustrated that eclogitization of an ocean plateau inhibits accretion by increasing slab negative buoyancy, although in some dynamic models, slab break-off leads to vertical accretion of the buoyant plateau beneath the overriding plate. Tetreault and Buiter (2012) suggested that buoyancy alone was not a barrier to subduction and showed accretion of a buoyant ocean plateau was partially dependent on the development of a basal detachment fault and the depth of this detachment.…”

Section: Subduction Modellingmentioning

confidence: 97%

Geodynamics of oceanic plateau and plume head accretion and their role in Phanerozoic orogenic systems of China

Betts

Moresi

Miller

et al. 2015

Geoscience Frontiers

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a b s t r a c tWe present three 3D numerical models of deep subduction where buoyant material from an oceanic plateau and a plume interact with the overriding plate to assess the influence on subduction dynamics, trench geometry, and mechanisms for plateau accretion and continental growth. Transient instabilities of the convergent margin are produced, resulting in: contorted trench geometry; trench migration parallel with the plate margin; folding of the subducting slab and orocline development at the convergent margin; and transfer of the plateau to the overriding plate. The presence of plume material beneath the oceanic plateau causes flat subduction above the plume, resulting in a "bowed" shaped subducting slab. In plateau-only models, plateau accretion at the edge of the overriding plate results in trench migration around the edge of the plateau before subduction is re-established directly behind the trailing edge of the plateau. The plateau shortens and some plateau material subducts. The presence of buoyant plume material beneath the oceanic plateau has a profound influence on the behaviour of the convergent margin. In the plateau þ plume model, plateau accretion causes rapid trench advance. Plate convergence is accommodated by shearing at the base of the plateau and shortening in the overriding plate. The trench migrates around the edge of the plateau and subduction is re-established well behind the trailing edge of the plateau, effectively embedding the plateau into the overriding plate. A slab window forms beneath the accreted plateau and plume material is transferred from the subducting plate to the overriding plate through the window. In all of the models, the subduction zone maintains a relatively stable configuration away from the buoyancy anomalies within the downgoing plate. The models provide a dynamic context for plateau and plume accretion in Phanerozoic accretionary orogenic systems such as the East China Orogen and the Central Asian Orogen (Altiads), which are characterised by accreted ophiolite complexes with diverse geochemical affinities, and a protracted evolution of accretion of exotic terranes including oceanic plateau and terranes with plume origins.

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Influence of geometry and eclogitization on oceanic plateau subduction

Cited by 81 publications

References 53 publications

The role of ridges in the formation and longevity of flat slabs

The role of ridges in the formation and longevity of flat slabs

Dynamic uplift during slab flattening

Geodynamics of oceanic plateau and plume head accretion and their role in Phanerozoic orogenic systems of China

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