Atmospheric Ar and Ne returned from mantle depths to the Earth’s surface by forearc recycling

Baldwin, Suzanne L.; Das, J. P.

doi:10.1073/pnas.1424122112

Cited by 13 publications

(9 citation statements)

References 51 publications

(133 reference statements)

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“…8). While the pressure-time paths of this (U)HP terrane are not yet determined with the same level of detail as for the Western Alps, available petrologic and geochronologic constraints (e.g., Baldwin et al, 2004Baldwin and Das, 2015) are consistent with exhumation paths computed by the numerical model (Fig. 8e), indicating fast decompression from mantle depths to the uppermost crust in 3-4 Myr.…”

Section: (U)hp Rock Exhumation In Eastern Pngmentioning

confidence: 82%

Divergent plate motion drives rapid exhumation of (ultra)high pressure rocks

Liao

Malusà

Zhao

et al. 2018

Earth and Planetary Science Letters

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Exhumation of (ultra)high pressure [(U)HP] rocks by upper-plate divergent motion above an unbroken slab, first proposed in the Western Alps, has never been tested by numerical methods. We present 2D thermo-mechanical models incorporating subduction of a thinned continental margin beneath either a continental or oceanic upper plate, followed by upper-plate divergent motion away from the lower plate. Results demonstrate how divergent plate motion may trigger rapid exhumation of large volumes of (U)HP rocks directly to the Earth's surface, without the need for significant overburden removal by erosion. Model exhumation paths are fully consistent with natural examples for a wide range of upper-plate divergence rates. Exhumation rates are systematically higher than the divergent rate imposed to the upper plate, and the modeled size of exhumed (U)HP domes is invariant for different rates of upper-plate divergence. Major variations are instead predicted at depth for differing model scenarios, as larger amounts of divergent motion may allow mantle-wedge exhumation to shallow depth under the exhuming domes. The transient temperature increase, due to ascent of mantle-wedge material in the subduction channel, has a limited effect on exhumed continental (U)HP rocks already at the surface. We test two examples, the Cenozoic (U)HP terranes of the Western Alps (continental upper plate) and eastern Papua New Guinea (oceanic upper plate). The good fit between model predictions and the geologic record in these terranes encourages the application of these models globally to pre-Cenozoic (U)HP terranes where the geologic record of exhumation is only partly preserved.

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Section: (U)hp Rock Exhumation In Eastern Pngmentioning

confidence: 82%

Divergent plate motion drives rapid exhumation of (ultra)high pressure rocks

Liao

Malusà

Zhao

et al. 2018

Earth and Planetary Science Letters

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“…This observation supports the notion 292" that the elemental fractionation predicted to occur under amphibole stability 293" conditions can be transferred to eclogite-facies minerals that can potentially convey 294" the signal into the deep mantle. Finally, Baldwin and Das (2015) used Ar and Ne 295" isotopic data for omphacite and phengite from Late Miocene coesite eclogite in Papua 296" New Guinea to argue that atmospheric Ar and Ne were incorporated during sub-297" solidus crystallization beneath the forearc. Our described mechanism of preferential 298" removal of light noble gases during prograde subduction would account for the source 299" of these atmosphere-derived gases.…”

Section: "mentioning

confidence: 99%

Noble gases recycled into the mantle through cold subduction zones

Smye

Jackson

Konrad‐Schmolke

et al. 2017

Earth and Planetary Science Letters

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Subduction of hydrous oceanic lithosphere replenishes the mantle volatile inventory. 27" Substantial uncertainties exist on the magnitudes of the recycled volatile fluxes and it 28" is unclear whether Earth surface reservoirs are undergoing net-loss or net-gain of H 2 O 29" and CO 2. Here, we develop noble gases as tracers for deep volatile cycling. 30" Specifically, we construct and apply a kinetic model to estimate the effect of 31" subduction zone metamorphism on the elemental composition of noble gases in 32" amphibole-a common constituent of altered oceanic crust. We show that progressive 33" dehydration of the slab leads to the extraction of noble gases, linking noble gas deep 34" cycling to H 2 O. Noble gases are strongly fractionated within hot subduction zones, 35" whereas minimal fractionation occurs along colder subduction geotherms. This 36" implies that the observed Ar-Kr-Xe elemental pattern of the mantle is dominated by 37" the injection of noble gases through colder subduction zones. We estimate a present-38" day bulk recycling efficiency of 5-35% and 60-80% for 36 Ar and H 2 O bound within 39" oceanic crust, respectively. Given that hotter subduction dominates over geologic 40" history, this result highlights the importance of cooler subduction zones in regassing 41" the mantle and in affecting modern volatile budget of Earth's interior. 42" 43" Keywords 44" 1. Noble gases 45" 2. Subduction zone processes 46" 3. Mantle geochemistry 47" 4. Deep water cycle 48" 49" 50" Kendrick et al., 2011). Metasomatised mantle wedge peridotites preserve elemental 64" noble gas compositions similar to sedimentary pore fluids (Kobayashi et al., 2016; 65" Sumino et al., 2010). This implies transport of seawater-derived noble gases to depths 66" approaching arc magma genesis. Mantle-derived well gases contain noble gas 67" abundance ratios similar to those of seawater (Holland and Ballentine, 2006), which is 68" distinctive from primordial components. This finding is corroborated by isotopic 69" observations that both MORB and OIB sources contain an atmospheric signature of 70" heavy noble gas abundances attributed to subduction (Caracausi et al.,

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“…T T T T r r r r identified in one sample at one outcrop in the D'Entrecasteaux Islands (16). The coesite eclogite at this locality is interpreted to have formed ∼8 Ma when a partial mantle melt intruded subducted continental lithosphere at UHP conditions (4,12,17). Since the discovery of coesite eclogite, attempts to find additional mineral evidence for UHP metamorphism from outcrop samples, including from felsic lithologies, have been unsuccessful.…”

Section: Fi F Fi F F F Fmentioning

confidence: 99%

“…In active plate boundary zones, where most igneous and metamorphic rocks form, the rock cycle involves localized lithospheric deformation, which exhumes rocks to the Earth's surface. When rock exhumation occurs at plate tectonic rates (centimeters year −1 ) (1, 2), high-and ultrahigh-pressure ((U) HP) metamorphic rocks containing hydrous mineral assemblages, trapped volatiles, and atmospheric gases (3,4) may be returned from upper mantle depths to the surface in the forearcs of subduction zones. Mechanically strong host minerals, such as garnet, zircon, and clinopyroxene, and their nondecrepitated mineral inclusions have played a key role in the identification of (U)HP metamorphic rocks and conditions of metamorphism (5).…”

mentioning

confidence: 99%

Garnet sand reveals rock recycling processes in the youngest exhumed high- and ultrahigh-pressure terrane on Earth

Baldwin

Schönig

Gonzalez

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Rock recycling within the forearcs of subduction zones involves subduction of sediments and hydrated lithosphere into the upper mantle, exhumation of rocks to the surface, and erosion to form new sediment. The compositions of, and inclusions within detrital minerals revealed by electron microprobe analysis and Raman spectroscopy preserve petrogenetic clues that can be related to transit through the rock cycle. We report the discovery of the ultrahigh-pressure (UHP) indicator mineral coesite as inclusions in detrital garnet from a modern placer deposit in the actively exhuming Late Miocene–Recent high- and ultrahigh-pressure ((U)HP) metamorphic terrane of eastern Papua New Guinea. Garnet compositions indicate the coesite-bearing detrital garnets are sourced from felsic protoliths. Carbonate, graphite, and CO2 inclusions also provide observational constraints for geochemical cycling of carbon and volatiles during subduction. Additional discoveries include polyphase inclusions of metastable polymorphs of SiO2 (cristobalite) and K-feldspar (kokchetavite) that we interpret as rapidly cooled former melt inclusions. Application of elastic thermobarometry on coexisting quartz and zircon inclusions in six detrital garnets indicates elastic equilibration during exhumation at granulite and amphibolite facies conditions. The garnet placer deposit preserves a record of the complete rock cycle, operative on <10-My geologic timescales, including subduction of sedimentary protoliths to UHP conditions, rapid exhumation, surface uplift, and erosion. Detrital garnet geochemistry and inclusion suites from both modern sediments and stratigraphic sections can be used to decipher the petrologic evolution of plate boundary zones and reveal recycling processes throughout Earth’s history.

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Atmospheric Ar and Ne returned from mantle depths to the Earth’s surface by forearc recycling

Cited by 13 publications

References 51 publications

Divergent plate motion drives rapid exhumation of (ultra)high pressure rocks

Divergent plate motion drives rapid exhumation of (ultra)high pressure rocks

Noble gases recycled into the mantle through cold subduction zones

Garnet sand reveals rock recycling processes in the youngest exhumed high- and ultrahigh-pressure terrane on Earth

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