Seismic anisotropy and slab dynamics from <i>SKS</i> splitting recorded in Colombia

Porritt, R. W.; Becker, T. W.; Monsalve, Gaspar

doi:10.1002/2014gl061958

Cited by 31 publications

(28 citation statements)

References 69 publications

(102 reference statements)

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“…Earlier studies relate the change of SKS orientations along the arc to a postulated slab tear and the resulting mantle flow (e.g. Porritt et al, 2014; Idárraga‐García et al, 2016). Our model provides a confirmation of this proposed slab tear and change in mantle flow.…”

Section: Resultsmentioning

confidence: 99%

Reproducing past subduction and mantle flow using high-resolution global convection models

Hu¹,

Liu²,

Zhou³

2018

Earth and Planetary Physics

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Plate subduction drives both the internal convection and the surface geology of the solid Earth. Despite the rapid increase of computational power, it remains challenging for geodynamic models to reproduce the history of Earth‐like subduction and associated mantle flow. Here, based on an adaptive approach of sequential data assimilation, we present a high‐resolution global model since the mid‐Mesozoic. This model incorporates the thermal structure and surface kinematics of tectonic plates based on a recent plate reconstruction to reproduce the observed subduction configuration and Earth‐like convection. Introduction of temperature‐ and composition‐dependent rheology allows for incorporation of many natural complexities, such as initiation of subduction zones, reversal of subduction polarity, and detailed plate‐boundary dynamics. The resultant present‐day slab geometry well matches Benioff zones and seismic tomography at depths < 1500 km, making it possible to hindcast past subduction dynamics and mantle flow. For example, the model produces a flat Farallon slab beneath North America during the Late Cretaceous to Early Cenozoic, a feature that has been geodynamically challenging to reproduce. This high‐resolution model can also capture details of the 4‐D evolution of slabs and the ambient mantle, such as temporally and spatially varying mantle flow associated with evolving slab geometry and buoyancy flux, as well as the formation of shallow slab tears due to subduction of young seafloors and the resulting complex mantle deformation. Such a geodynamic framework serves to further constrain uncertain plate reconstruction in the geological past, and to better understand the origin of enigmatic mantle seismic features.

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Section: Resultsmentioning

confidence: 99%

Reproducing past subduction and mantle flow using high-resolution global convection models

Hu¹,

Liu²,

Zhou³

2018

Earth and Planetary Physics

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“…However, the interpretation of seismic anisotropy in subduction zones can be quite challenging, in large part because commonly used seismic phases sample a number of distinct portions of the subduction systems, including the overriding plate, the mantle wedge above the slab, the slab itself, and the subslab mantle. These difficulties have been particularly acute for the South American subduction region; although a large number of studies have been carried out [e.g., Russo and Silver , ; Bock et al ., ; Polet et al ., ; Anderson et al ., ; MacDougall et al ., ; Hicks et al ., ; Eakin and Long , ; Porritt et al ., ; Wölbern et al ., ; Eakin et al ., ], interpretations are often nonunique and hampered by complexities in observed splitting patterns and the likely presence of multiple layers of anisotropy at depth.…”

Section: Introductionmentioning

confidence: 97%

Overriding plate, mantle wedge, slab, and subslab contributions to seismic anisotropy beneath the northern Central Andean Plateau

Long

Biryol

Eakin

et al. 2016

Geochem Geophys Geosyst

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The Central Andean Plateau, the second‐highest plateau on Earth, overlies the subduction of the Nazca Plate beneath the central portion of South America. The origin of the high topography remains poorly understood, and this puzzle is intimately tied to unanswered questions about processes in the upper mantle, including possible removal of the overriding plate lithosphere and interaction with the flow field that results from the driving forces associated with subduction. Observations of seismic anisotropy can provide important constraints on mantle flow geometry in subduction systems. The interpretation of seismic anisotropy measurements in subduction settings can be challenging, however, because different parts of the subduction system may contribute, including the overriding plate, the mantle wedge above the slab, the slab itself, and the deep upper mantle beneath the slab. Here we present measurements of shear wave splitting for core phases (SKS, SKKS, PKS, and sSKS), local S, and source‐side teleseismic S phases that sample the upper mantle beneath southern Peru and northern Bolivia, relying mostly on data from the CAUGHT experiment. We find evidence for seismic anisotropy within most portions of the subduction system, although the overriding plate itself likely makes only a small contribution to the observed delay times. Average fast orientations generally trend roughly trench‐parallel to trench‐oblique, contradicting predictions from the simplest two‐dimensional flow models and olivine fabric scenarios. Our measurements suggest complex, layered anisotropy beneath the northern portion of the Central Andean Plateau, with significant departures from a two‐dimensional mantle flow regime.

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“…Among these, mantle flow around single slabs is, in models, perpendicular to the trench toward the center of the subduction zone (above and below the slab), while near the slab edges the flow turns toward a more trench‐parallel direction (e.g., Faccenda & Capitanio, ; Long, ). However, these flow directions are not easily reconciled with observations, and may be affected by tectonic complexities, such as the presence of nearby slabs, slab windows or mantle plumes (e.g., Burkett & Billen, ; Di Leo et al, ; Druken et al, ; Guillaume et al, ; Király et al, ; MacDougall et al, ; Mériaux et al, ; Porritt et al, ; Salimbeni et al, ).…”

Section: Introductionmentioning

confidence: 99%

Modeling Slab‐Slab Interactions: Dynamics of Outward Dipping Double‐Sided Subduction Systems

Király

Holt

Funiciello

et al. 2018

Geochem Geophys Geosyst

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Slab‐slab interaction is a characteristic feature of tectonically complex areas. Outward dipping double‐sided subduction is one of these complex cases, which has several examples on Earth, most notably the Molucca Sea and Adriatic Sea. This study focuses on developing a framework for linking plate kinematics and slab interactions in an outward dipping subduction geometry. We used analog and numerical models to better understand the underlying subduction dynamics. Compared to a single subduction model, double‐sided subduction exhibits more time‐dependent and vigorous toroidal flow cells that are elongated (i.e., not circular). Because both the Molucca and Adriatic Sea exhibit an asymmetric subduction configuration, we also examine the role that asymmetry plays in the dynamics of outward dipping double‐sided subduction. We introduce asymmetry in two ways; with variable initial depths for the two slabs (“geometric” asymmetry), and with variable buoyancy within the subducting plate (“mechanical” asymmetry). Relative to the symmetric case, we probe how asymmetry affects the overall slab kinematics, whether asymmetric behavior intensifies or equilibrates as subduction proceeds. While initial geometric asymmetry disappears once the slabs are anchored to the 660 km discontinuity, the mechanical asymmetry can cause more permanent differences between the two subduction zones. In the most extreme case, the partly continental slab stops subducting due to the unequal slab pull force. The results show that the slab‐slab interaction is most effective when the two trenches are closer than 10–8 cm in the laboratory, which is 600–480 km when scaled to the Earth.

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Seismic anisotropy and slab dynamics from SKS splitting recorded in Colombia

Cited by 31 publications

References 69 publications

Reproducing past subduction and mantle flow using high-resolution global convection models

Reproducing past subduction and mantle flow using high-resolution global convection models

Overriding plate, mantle wedge, slab, and subslab contributions to seismic anisotropy beneath the northern Central Andean Plateau

Modeling Slab‐Slab Interactions: Dynamics of Outward Dipping Double‐Sided Subduction Systems

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