The role of pargasitic amphibole in the formation of major geophysical discontinuities in the shallow upper mantle

Kovàcs, István; Lenkey, László; Green, David H.; Fancsik, Tamás; Falus, György; Kiss, János; Orosz, László; Angyal, Jolán; Vikor, Zsuzsanna

doi:10.1007/s40328-016-0191-3

Cited by 23 publications

(16 citation statements)

References 81 publications

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“…break‐up of the overriding plate? How relevant are magmatically induced weakening of the continental lithosphere (e.g., Bahadori & Holt, 2019; Sobolev et al., 2011) and the existence of mid‐lithospheric discontinuity (e.g., Kovács et al., 2017; Rychert & Shearer, 2009; Selway et al., 2015)? Can hydrous (i.e., compositionally buoyant) plumes trigger similar downthrusting of the mantle lithosphere to thermal plumes (e.g., Kuritani et al., 2019)?…”

Section: Discussionmentioning

confidence: 99%

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Plume‐Induced Sinking of Intracontinental Lithospheric Mantle: An Overlooked Mechanism of Subduction Initiation?

Cloetingh

Koptev

Kovàcs

et al. 2021

Geochem Geophys Geosyst

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Although many different mechanisms for subduction initiation have been proposed, only few of them are viable in terms of consistency with observations and reproducibility in numerical experiments. In particular, it has recently been demonstrated that intra‐oceanic subduction triggered by an upwelling mantle plume could greatly contribute to the onset and operation of plate tectonics in the early and, to a lesser degree, modern Earth. On the contrary, the initiation of intra‐continental subduction still remains underappreciated. Here we provide an overview of 1) observational evidence for upwelling of hot mantle material flanked by downgoing proto‐slabs of sinking continental mantle lithosphere, and 2) previously published and new numerical models of plume‐induced subduction initiation. Numerical modeling shows that under the condition of a sufficiently thick (>100 km) continental plate, incipient downthrusting at the level of the lowermost lithospheric mantle can be triggered by plume anomalies of moderate temperatures and without significant strain‐ and/or melt‐related weakening of overlying rocks. This finding is in contrast with the requirements for plume‐induced subduction initiation within oceanic or thinner continental lithosphere. As a result, plume‐lithosphere interactions within continental interiors of Paleozoic‐Proterozoic‐(Archean) platforms are the least demanding (and thus potentially very common) mechanism for initiation of subduction‐like foundering in the Phanerozoic Earth. Our findings are supported by a growing body of new geophysical data collected in various intra‐continental areas. A better understanding of the role of intra‐continental mantle downthrusting and foundering in global plate tectonics and, particularly, in the initiation of “classic” ocean‐continent subduction will benefit from more detailed follow‐up investigations.

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Section: Discussionmentioning

confidence: 99%

“…break-up of the overriding plate? How relevant are magmatically-induced weakening of the continental lithosphere (e.g., Sobolev et al, 2011;Bahadori & Holt, 2019) and the existence of mid-lithospheric discontinuity (e.g., Rychert & Shearer, 2009;Selway et al, 2015;Kovács et al, 2017)? Can hydrous (i.e.…”

Section: Accepted Articlementioning

confidence: 99%

Plume‐Induced Sinking of Intracontinental Lithospheric Mantle: An Overlooked Mechanism of Subduction Initiation?

Cloetingh

Koptev

Kovàcs

et al. 2021

Geochem Geophys Geosyst

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“…The water content of the bulk peridotites is controlled by orthopyroxene and clinopyroxene, except in amphibole‐rich samples, where postkinematic, late‐stage amphibole formation enriched the samples in water. Equilibrium temperature can have a huge effect on the distribution of hydrogen in the mantle peridotites since pargasite, which is the main host of hydroxyl, is stable only under ~1100°C and ~3 GPa (Green et al, ; Kovács, Green, et al, ; Kovács et al ). Beyond the stability of pargasite, the hydrogen resides mainly in the NAMs and in a free fluid/melt phase may be present.…”

Section: Discussionmentioning

confidence: 99%

Fluid‐Enhanced Annealing in the Subcontinental Lithospheric Mantle Beneath the Westernmost Margin of the Carpathian‐Pannonian Extensional Basin System

et al. 2017

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Mantle xenoliths from the Styrian Basin Volcanic Field (Western Pannonian Basin, Austria) are mostly coarse granular amphibole‐bearing spinel lherzolites with microstructures attesting for extensive annealing. Olivine and pyroxene CPO (crystal‐preferred orientation) preserve nevertheless the record of coeval deformation during a preannealing tectonic event. Olivine shows transitional CPO symmetry from [010]‐fiber to orthogonal type. In most samples with [010]‐fiber olivine CPO symmetry, the [001] axes of the pyroxenes are also dispersed in the foliation plane. This CPO patterns are consistent with lithospheric deformation accommodated by dislocation creep in a transpressional tectonic regime. The lithospheric mantle deformed most probably during the transpressional phase after the Penninic slab breakoff in the Eastern Alps. The calculated seismic properties of the xenoliths indicate that a significant portion of shear wave splitting delay times in the Styrian Basin (0.5 s out of approximately 1.3 s) may originate in a highly annealed subcontinental lithospheric mantle. Hydroxyl content in olivine is correlated to the degree of annealing, with higher concentrations in the more annealed textures. Based on the correlation between microstructures and hydroxyl content in olivine, we propose that annealing was triggered by percolation of hydrous fluids/melts in the shallow subcontinental lithospheric mantle. A possible source of these fluids/melts is the dehydration of the subducted Penninic slab beneath the Styrian Basin. The studied xenoliths did not record the latest large‐scale geodynamic events in the region—the Miocene extension then tectonic inversion of the Pannonian Basin.

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“…1029/2021TC006711 et al, 2015Maurya et al, 2016;Selway et al, 2015). Although the exact origins and rheological properties of the MLD remain controversial (Aulbach et al, 2017;Hansen et al, 2012;Karato et al, 2015;Rader et al, 2015;Selway et al, 2015;Wang et al, 2016;, it is generally accepted that MLDs exist at ∼80-100 km depth with a ∼10-40 km thickness, and that they are rheologically weaker than their overlying and underlying lithospheric mantle (Abt et al, 2010;Aulbach et al, 2017;Chen et al, 2014;Hopper & Fischer, 2015;Hopper et al, 2014;Kennett & Sippl, 2018;Kovács et al, 2017;Nita et al, 2016;Saha et al, 2021;Selway et al, 2015;Sun et al, 2018;Wang & Kusky, 2019;. A weak MLD layer could strongly affect the cratonic lithospheric thinning under different tectonic settings (Wang & Kusky, 2019), especially when the weak MLD layer comes into contact with hot asthenosphere (Liu et al, 2018a(Liu et al, , 2018b.…”

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confidence: 99%

Connection Between a Subcontinental Plume and the Mid‐Lithospheric Discontinuity Leads to Fast and Intense Craton Lithospheric Thinning

Shi

Chen

et al. 2021

Tectonics

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Thinning of these cratonic lithospheres has occurred under different tectonic settings, in particular being associated with interactions with nearby oceanic subduction or an underlying mantle plume. Lithospheric thinning beneath the North China Craton and the Wyoming Craton in North America is generally considered to be related to subduction-induced lithospheric modification (Figure 1). For example, the lithospheric thickness of the North China Craton was reduced from 200 to 100 km since the Paleozoic (

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The role of pargasitic amphibole in the formation of major geophysical discontinuities in the shallow upper mantle

Cited by 23 publications

References 81 publications

Plume‐Induced Sinking of Intracontinental Lithospheric Mantle: An Overlooked Mechanism of Subduction Initiation?

Plume‐Induced Sinking of Intracontinental Lithospheric Mantle: An Overlooked Mechanism of Subduction Initiation?

Fluid‐Enhanced Annealing in the Subcontinental Lithospheric Mantle Beneath the Westernmost Margin of the Carpathian‐Pannonian Extensional Basin System

Connection Between a Subcontinental Plume and the Mid‐Lithospheric Discontinuity Leads to Fast and Intense Craton Lithospheric Thinning

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