Microfabrics of omphacite and garnet in eclogite from the Lanterman Range, northern Victoria Land, Antarctica

Kim, Daeyeong; Kim, Tae‐Hwan; Lee, Jeongmin; Kim, Yoonsup; Kim, Hyeoncheol; Lee, Jong Ik

doi:10.1007/s12303-018-0055-7

Cited by 13 publications

(10 citation statements)

References 74 publications

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“…This is consistent with the results shown in Kim et al. (2018). During the subduction, the LPO of anisotropic omphacite induced by ductile deformation is the main contributor to seismic anisotropy of the subducted basaltic rocks in the upper mantle (e.g., Zhang et al., 2006).…”

Section: Discussionsupporting

confidence: 94%

“…found that even though garnet, which is nearly elastically isotropic (Sinogeikin & Bass, 2000), is the volumetrically more abundant phase in some of their samples (up to 87 vol%), omphacite dominates seismic anisotropy of eclogite. This is consistent with the results shown in Kim et al (2018).…”

Section: Seismic Anisotropy Of Deformed Eclogite In the Subducted Slab Crustsupporting

confidence: 94%

“…At relatively low pressure‐temperature conditions (6 GPa and 1000 K), the V p anisotropy of omphacite is ∼7.2%. Considering the omphacite volume fraction of ∼70% and the random orientation of the nearly isotropic garnet (Kim et al., 2018; Sinogeikin & Bass, 2000; Wang et al., 2009) in eclogite, the V p anisotropy of eclogite is on the order of 5%–6% in the shallower upper mantle. When reaching ∼14 GPa and 1800 K at transition zone depths, the V p anisotropy of omphacite increases to 8.2%.…”

Section: Discussionmentioning

confidence: 99%

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Seismic Visibility of Eclogite in the Earth’s Upper Mantle—Implications From High Pressure‐Temperature Single‐Crystal Elastic Properties of Omphacite

et al. 2021

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The Earth's oceanic crust is primarily made of basalt. When the oceanic lithosphere is subducted, the basaltic oceanic crust metamorphizes into eclogite when the pressure and temperature exceed 2 GPa and 1073 K (Ito & Kennedy, 1971). Due to its high density, the formation of eclogite further helps the slab subduction (Moghadam et al., 2010;Xu et al., 2008). Omphacite, the solid solution of diopside (CaMgSi 2 O 6 ) and jadeite (NaAlSi 2 O 6 ), is the major mineral phase in eclogite (up to 75 vol%) and can stably exist at depths up to 500 km. Due to the slow mixing and diffusion process within the Earth's interior, the recycled eclogitic materials can be preserved over the geological time as chemical heterogeneities in the deep Earth (Ballmer et al., 2017;Xu et al., 2008). To seismically identify those heterogeneities, the high pressure-temperature elastic properties of relevant minerals are needed.Seismologists have found complex seismic anisotropy features near subduction zones (e.g., Long & Silver, 2008;Niday & Humphreys, 2020), which are generally explained as the result of the flow-induced lattice-preferred orientation (LPO) of the elastically anisotropic minerals. Understanding the seismic anisotropy observations as well as the mantle flow field requires knowledge of the single-crystal elasticity and the LPO of relevant minerals, such as omphacite in the subducted slab crust.

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Section: Discussionsupporting

confidence: 94%

Section: Seismic Anisotropy Of Deformed Eclogite In the Subducted Slab Crustsupporting

confidence: 94%

Section: Discussionmentioning

confidence: 99%

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Seismic Visibility of Eclogite in the Earth’s Upper Mantle—Implications From High Pressure‐Temperature Single‐Crystal Elastic Properties of Omphacite

et al. 2021

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“…Previous studies on the LPO-induced seismic properties of eclogite-facies rocks have mainly focused on the role of omphacite (± garnet) (Ábalos et al, 2011;Bascou et al, 2001;Kim et al, 2018), lawsonite (Cao & Jung, 2016;Kim et al, 2016), retrogressed assemblages (amphibole, epidote, and plagioclase) (Keppler et al, 2015;Llana-Fúnez & Brown, 2012;McNamara et al, 2012;Shi et al, 2010), and comparisons between eclogite and blueschist (or peridotite) (Ábalos et al, 2011;Cao et al, 2013;Keppler et al, 2015;Worthington et al, 2013). Although phengite is a common high-pressure phase in eclogite-facies rocks from numerous locations worldwide (Angiboust et al, 2014;Bukała et al, 2018;Carswell et al, 1997;Groppo et al, 2007;Massonne & Kopp, 2004;Nakamura, 2003;Tsujimori et al, 2006;Zhang et al, 2009), studies on the seismic properties of phengite in eclogites have been limited (Keppler et al, 2015;Puelles et al, 2017;Worthington et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Relationships Between Eclogite‐Facies Mineral Assemblages, Deformation Microstructures, and Seismic Properties in the Yuka Terrane, North Qaidam Ultrahigh‐Pressure Metamorphic Belt, NW China

Park

Jung

2019

JGR Solid Earth

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To understand the relationships between eclogite‐facies mineral assemblages, deformation microstructures, and the seismic properties of subducting oceanic crust, eclogites from the Yuka terrane, North Qaidam ultrahigh‐pressure metamorphic belt, NW China, were studied. Observations of mineral textures, deformation microstructures, and petrofabrics in the eclogites indicate that garnet, omphacite, and phengite were deformed by intracrystalline deformation (i.e., dislocation creep) during prograde metamorphism. In contrast, amphibole, which was formed by the topotactic replacement of omphacite at fluid‐present conditions, is considered to have been deformed by diffusional flow (dissolution‐precipitation creep) during amphibolite‐facies retrogression associated with exhumation. Based on the petrofabrics in the samples, the seismic properties of the eclogites were calculated depending on eclogite‐facies mineral assemblages such as garnet + omphacite, garnet + omphacite + phengite, garnet + omphacite + phengite + lawsonite, garnet + omphacite + phengite + amphibole, and garnet + omphacite + amphibole. We found that the seismic signatures of each of the eclogite‐facies mineral assemblages were different. In particular, phengite‐bearing eclogites (the garnet + omphacite + phengite/garnet + omphacite + phengite + amphibole assemblages), depending on phengite content, produced the strongest seismic anisotropy (AVp and AVs), with a strong polarization anisotropy, that was at least three times higher than bimineralic (phengite‐absent) eclogites (garnet + omphacite assemblage). Our results indicate that phengite, as a stable phase at high‐pressure and high‐temperature conditions, can play an important role in the creation of trench‐parallel seismic anisotropy in the eclogite‐facies mineral assemblages found in subduction zones.

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“…Natural silicates were used as standards, and matrix corrections were calculated using a ZAF correction program. The detailed analytical procedure of FE-EPMA is described in Kim et al (2018). Before analysis, the obsidian samples were photographed and imaged by field-emission-type scanning electron microscope (FE-SEM) JEOL JSM-7601F at the Gyeongsang National University.…”

Section: Methodsmentioning

confidence: 99%

Two Contrasting Provenances of Prehistoric Obsidian Artifacts in South Korea: Mineralogical and Geochemical Characteristics

Jwa

Jin

et al. 2019

Open Archaeology

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Two provenances – Mount Baekdusan near Sino-Korean border and Kyushu of southwest Japan – are well known for Korean prehistoric obsidian artifacts. We examined the mineralogical and geochemical characteristics of the Baekdusan obsidians and the Kyushu obsidians. Though obsidians are of glassy material, microlites are easily found in the host matrix. Fe-oxides are the most abundant microlite phase, with a lesser amount of clinopyroxene, feldspar, and biotite. It is notable that the texture and chemical composition of the microlites in the Baekdusan obsidians are quite different from those in the Kyushu obsidians. Clinopyroxene in the Baekdusan obsidians occurs as oikocryst enclosing smaller Fe-oxides, and has the composition of hedenbergite to augite. On the other hand, clinopyroxene in the Kyushu obsidians is compositionally of clinoferrosilite, and shows intergrowth and/or overgrowth textures with Fe-oxides. Feldspar microlites in the Baekdusan obsidians are generally of sanidine to anorthoclase, whereas those in the Kyushu obsidians of oligoclase. Biotite microlites are often found in the Kyushu obsidians, but absent in the Baekdusan obsidians. Also, there exist prominent geochemical contrasts between the Baekdusan obsidians and the Kyushu obsidians. At the similar SiO2 range of 74 to 78 wt.% the host glasses of the Baekdusan obsidians have higher contents of TiO2, total FeO, K2O, Nb, Hf, Zr, Ta, Y and rare earth elements (REEs) than those of the Kyushu obsidians. The overall mineralogical and geochemical contrasts for the Baekdusan and Kyushu obsidians seem to reflect different parental magma composition and crystallization environment. This distinction can be used to establish the provenance of the obsidian artifacts from the prehistoric sites in the Korean Peninsula as well as contiguous areas such as China, Japan, and Russia.

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Microfabrics of omphacite and garnet in eclogite from the Lanterman Range, northern Victoria Land, Antarctica

Cited by 13 publications

References 74 publications

Seismic Visibility of Eclogite in the Earth’s Upper Mantle—Implications From High Pressure‐Temperature Single‐Crystal Elastic Properties of Omphacite

Seismic Visibility of Eclogite in the Earth’s Upper Mantle—Implications From High Pressure‐Temperature Single‐Crystal Elastic Properties of Omphacite

Relationships Between Eclogite‐Facies Mineral Assemblages, Deformation Microstructures, and Seismic Properties in the Yuka Terrane, North Qaidam Ultrahigh‐Pressure Metamorphic Belt, NW China

Two Contrasting Provenances of Prehistoric Obsidian Artifacts in South Korea: Mineralogical and Geochemical Characteristics

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