Zircon xenocryst evidence for crustal recycling at the Mid-Atlantic Ridge

Беа, Ф.; Бортников, Н. С.; Montero, P.; Zinger, T. F.; Шарков, Е. В.; Silantyev, S. A.; Skolotnev, S. G.; Trukhalev, Arkadi; Molina, J.F.

doi:10.1016/j.lithos.2019.105361

Cited by 27 publications

(20 citation statements)

References 54 publications

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“…This also suggests that not only subduction‐enriched, but also plume‐modified asthenospheric anomalies may be long‐lived and could therefore be eventually juxtaposed with lithosphere that came from thousands of kilometers away or that formed much later. Such long‐term survival of geochemically anomalous asthenospheric regions may provide a potential avenue for explaining other enigmatic findings such as ancient zircons within modern mid‐ocean ridge settings (Cheng et al, 2016; Pilot et al, 1998; Bea et al, 2020). Reworking of subducted zircons in arcs has, for instance, been demonstrated in the Caribbean region (Rojas‐Agramonte et al, 2016, 2017; Torró et al, 2018) showing that zircons survive mantle wedge pressure and temperature conditions.…”

Section: Implications For Geodynamicsmentioning

confidence: 99%

Arc‐Type Magmatism Due to Continental‐Edge Plowing Through Ancient Subduction‐Enriched Mantle

Hinsbergen

Spakman

Boorder

et al. 2020

Geophysical Research Letters

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The puzzling <7 Ma old "postsubduction" arc magmatism of New Guinea contains geochemical subduction-type signatures yet did not occur above an active subduction zone. Here we show that these arc magmas formed at the North Australian continental lithospheric edge when it plowed northward through mantle above the detached Arafura slab remnant. This mantle preserved its subduction signature and the edge plowing process generated new melts that ascended via an active transform fault. Arafura slab subduction occurred at an intraoceanic subduction zone that ended~30-25 Ma ago, when the Australian continental edge was still~1,000 km to the south. Our absolute plate tectonic reconstruction of continental-edge plowing suggests that ancient mantle wedges remain semistationary in the upper mantle and can preserve their geochemical signature for tens of Ma, explaining previously enigmatic "postsubduction" arc magmatism.Plain Language Summary During subduction, downgoing plate lithosphere ("slab") releases water to the overlying mantle causing so-called "arc volcanism." A puzzling class of "postsubduction" arc magmatism bears geochemical signatures of subduction but occurs in a setting without subduction. Here we show that this magmatism is the result of remelting of mantle portions that were previously enriched by ancient subduction zones, slab relics of which are now found with seismological techniques below these enriched portions. From famous postarc magmatic rocks on New Guinea we identify that the "plowing" of the edge of a thick, continental lithosphere through a previously enriched mantle portion may provide a cause of melting, producing arc-like magmatism. We also identify that pathways for the melts to rise to (close to) the surface, provided by major faults, are essential. The "New Guinea recipe" also explains magmatism on the Fiji Islands, California, and Colombia. A major implication of our work is that asthenospheric upper mantle rocks appear to move much slower than plates, such that lithosphere may have undergone a very different geological history than the currently underlying mantle.

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Section: Implications For Geodynamicsmentioning

confidence: 99%

Arc‐Type Magmatism Due to Continental‐Edge Plowing Through Ancient Subduction‐Enriched Mantle

Hinsbergen

Spakman

Boorder

et al. 2020

Geophysical Research Letters

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“…The unexpected presence of Precambrian zircons in the young oceanic lithosphere requires a careful appraisal. A possible explanation is that these zircons were recycled from older crustal rocks in the mantle source e.g., 2,4 . Earlier reports of inherited zircons in mantle-derived rocks often assumed that their studied grains belonged to that speci c sample, however, U-Pb dates alone do not rule out other explanations.…”

Section: Resultsmentioning

confidence: 99%

“…Inherited zircons (ZrSiO 4 ), displaying U-Pb dates older than their host-rock, are a common feature of felsic rocks and are increasingly being reported from ma c and ultrama c rocks from both oceanic [2][3][4][5][6][7][8] and continental [9][10][11][12][13][14][15] environments. While the ability to inherit older zircons in continental settings remains indisputable, reports suggesting that zircons can survive and retain their U-Pb dates under certain chemical conditions in the mantle 10,16,17 indicate that zircons may be recycled through the mantle and therefore appear in mantle peridotites or mantle-derived igneous rocks.…”

Section: Introductionmentioning

confidence: 99%

Inherited Continental Zircons in Oceanic Rocks – True or False

Bjerga

Stubseid

Pedersen

et al. 2021

Preprint

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Many studies have reported U-Pb dates of zircons that are older than the rocks that contain them, and they are therefore thought to be inherited from older rock complexes. Their presence has profound geodynamic implications and has been used to hypothesize about concealed micro-continents, continental crust beneath ocean islands, and recycling of continental material in the mantle beneath mid-ocean ridges. However, there is skepticism in the scientific community whether these zircons are truly inherited from crustal fragments or represent contaminants from sample preparation and processing. In this study, we combine single zircon U-Pb dates with structural radiation damage determined by Raman spectroscopy from a Pliocene mid-ocean ridge gabbro and show that the thermal history of Precambrian zircons found in the sample contradicts an inherited origin. To confirm that our approach allows distinction between contamination and true inherited zircons, we investigated igneous rocks that formed during the opening of the Atlantic Ocean and find that the calculated radiation damage age of old inherited grains corresponds with the crystallization dates of the young magmatic zircons.

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“…2a) by the appearance of low εHf(t) and high The non-GPA zircon grains indicate old (>213 Ma) to recent (~20 Ma, for the outlier) external sources not related to plume activity. The absence of continental basement below the Galápagos Archipelago 28,29 rules out the possibility of continental crust provenance, as could apply to other oceanic environments 30,31,32 . Given the uncertainty about the source of the exotic non-GPA zircons and because they are not direct magmatic products of plume activity, their provenance exceeds the scope of this study and is not further discussed here.…”

mentioning

confidence: 99%

Asthenospheric zircon below Galápagos dates plume activity

Rojas‐Agramonte¹,

Kaus

Piccolo

et al. 2021

Preprint

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Mantle plumes are active for long periods of time1,2, however dating the onset of their activity is difficult. The magmatic products of the Galápagos plume, for example, have been subducted and fragmentarily accreted to the Caribbean and South American plates3,4. Based on submarine and terrestrial exposures it is inferred that the plume has been operating for ~90 Myrs5 or perhaps even longer (e.g., ~139 Myrs6). Here we show that the activity of the plume dates back to ~170 Ma. Evidence for this comes from 0 to 168 Ma zircon with isotopic plume signature (Galápagos Plume Array; GPA) recovered from lavas and sediments from ten islands of the archipelago. Given lithospheric plate motion, this result implies that GPA zircon predating the Galápagos lithosphere (i.e., >14 Ma) formed at asthenospheric depths. Thermo-mechanical numerical experiments of plume-lithosphere interaction show that old zircon grains can be stored within local astenospheric stable domains to be later captured by subsequent rising plume magmas. These results open new avenues for research on mantle plume dynamics in similar tectonic settings.

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Zircon xenocryst evidence for crustal recycling at the Mid-Atlantic Ridge

Cited by 27 publications

References 54 publications

Arc‐Type Magmatism Due to Continental‐Edge Plowing Through Ancient Subduction‐Enriched Mantle

Arc‐Type Magmatism Due to Continental‐Edge Plowing Through Ancient Subduction‐Enriched Mantle

Inherited Continental Zircons in Oceanic Rocks – True or False

Asthenospheric zircon below Galápagos dates plume activity

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