The stability of subducted glaucophane with the Earth’s secular cooling

Bang, Yoonah; Hwang, Ho Kyoung; Kim, Taehyun; Cynn, Hyunchae; Park, Yong; Jung, Haemyeong; Park, Changyong; Popov, Dmitry; Prakapenka, Vitali B.; Wang, Lin; Liermann, H. P.; Irifune, Tetsuo; Mao, Ho Kwang; Lee, Yong Jae

doi:10.1038/s41467-021-21746-8

Cited by 14 publications

(9 citation statements)

References 68 publications

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“…High pressure deformation experiments conducted at 730°C at 2 GPa for 9 hr on a natural blueschist with 55 vol. % glaucophane shows partially reacted amphibole grains where an intergrowth texture develops within glaucophane (see Figure 3b in Bang et al., 2021). Similar to our experiments, the intergrowth texture occurs along both linear crystallographically controlled microfractures as well as throughout amphibole grain interiors.…”

Section: Discussionmentioning

confidence: 98%

Diffusion Creep of Sodic Amphibole‐Bearing Blueschist Limited by Microboudinage

Tokle,

Hufford,

Behr

et al. 2023

JGR Solid Earth

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To investigate the mechanical and microstructural properties of mafic blueschists, we conducted deformation experiments on powdered natural blueschist aggregates using the general shear geometry in the Griggs apparatus. Experiments were performed at ∼1.0 GPa and temperatures ranging from 650‐700°C. The blueschist starting material consists primarily of sodic amphibole and epidote, with minor amounts of quartz, titanite, albite, and white mica. Strain rate stepping experiments provided mechanical data with stress exponents ranging from 1.8 to 2.2. Microstructural analysis of both the hydrostatic and deformed samples show that the blueschist aggregates were deforming by microboudinage of the sodic amphibole, with a chemically new sodic‐calcic amphibole diffused into the boudin neck. Based on these results, we interpret the samples to have deformed by diffusion creep of the sodic‐calcic amphibole, which was rate‐limited by diffusion into the boudin neck. We developed a microboudinage diffusion creep flow law using a least square regression, with parameters of A = 2.43e11 MPa‐n μm s‐1, n = 2.0 ± 0.3, m = 1.0, and Q = 384 ± 15 kJ/mol. Extrapolation of the flow law to the blueschist stability field suggests viscosities that are higher than metasedimentary rocks (quartz dislocation creep flow law) and lower than eclogitic rocks (omphacite dislocation creep flow law) consistent with field observations. We also show that this type of deformation mechanism matches observations of natural rocks in paleosubduction zone environments, supporting the application of this flow law to estimate amphibole rheology in modern subduction zones.

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Section: Discussionmentioning

confidence: 98%

Diffusion Creep of Sodic Amphibole‐Bearing Blueschist Limited by Microboudinage

Tokle,

Hufford,

Behr

et al. 2023

JGR Solid Earth

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“…Lee et al (2021) used thermal models of cold subduction zones to argue for the stability of chloritoid and its contribution to the relatively strong trench-parallel seismicity observed in such regions. Bang et al (2021) used thermal models to study the stability of subducted glaucophane over Earth's thermal evolution. Codillo et al (2022) showed chlorite is preferentially formed over talc during Si-metasomatism of ultramafic rocks while also suggesting a limited rheological role of talc in determining the physical structure of subduction zones (as suggested to the contrary by Peacock and Wang, 2021).…”

Section: Design and Interpretation Of Physical Experimentsmentioning

confidence: 99%

An introductory review of the thermal structure of subduction zones: I. Motivation and selected examples

Keken¹,

Wilson

2023

Preprint

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The thermal structure of subduction zones is fundamental to our understanding of physical and chemical processes that occur at active convergent plate margins. These include magma generation and related arc volcanism, shallow and deep seismicity, and metamorphic reactions that can release fluids. Computational models can predict the thermal structure to great numerical precision when models are fully described but this does not guarantee accuracy or applicability. In a pair of companion papers the construction of thermal subduction zone models, their use in subduction zone studies, and their link to geophysical and geochemical observations is explored. In part I the motivation to understand the thermal structure is presented based on experimental and observational studies. This is followed by a description of a selection of thermal models for the Japanese subduction zones.

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“…The heavy minerals identified in this study include the opaques (magnetite, ilmenite, Cr-spinel), metastable minerals (garnet, apatite, zoisite, epidote, hornblende, actinolite, tremolite-actinolite, glaucophane, aegirine) and ultrastable minerals (zircon, rutile and tourmaline). Glaucophane, a sodic amphibole diagnostic for the blueschist facies together with either lawsonite or epidote, is particularly important as a provenance indicator characterizing the subduction zone and process (Bang et al, 2021). Both glaucophane and epidote are among the heavy minerals detected in the sandstones of Injana Formation.…”

Section: Whole-rock Geochemistrymentioning

confidence: 99%

Petrography and geochemistry of sandstones from the Injana Formation, Hemrin South Mountain, Northern Iraq: Implications for provenance, weathering and tectonic setting

Kettanah

Abdulrahman

2022

Geological Journal

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The sandstones of Upper Miocene Injana Formation were studied petrographically and geochemically in the Hemrin South Mountain area, northern Iraq. The sandstones vary between arkose and lithic arkose in composition (Q 50 F 24 L 26 ) and are compositionally and texturally immature; meanwhile, the Log(Fe 2 O 3 /K 2 O)-Log(SiO 2 / Al 2 O 3 ) diagram shows that they are divided between arkose, litharenite and wacke.These sandstones contain a wide spectrum of heavy minerals ranging from the most resistant ultrastable minerals (zircon, rutile and tourmaline), to the least resistant nonstable minerals (amphiboles and pyroxenes). The provenance indicator diagrams Q m FL t and Q t FL indicate multi-sources for these sandstones ranging from transitional craton, arc and recycled sediments. The major element provenance discriminant function plot shows that they are derived mostly from intermediate igneous provenance.All these suggest that the probable source of these sandstones is the igneousmetamorphic rocks including the ophiolites of the Suture Zone, the imbricate zone, the Shalair-Sanandaj-Sirjan Terrane and the complimentary rock units in Turkey and Iran. The presence of glaucophane as the provenance indicator mineral for subduction zones is a further proof of the ophiolites having acted as the source rocks. Geochemically, the sandstones are enriched in Ca, V, Cr, Ni, Cu, Mo, Sn and Sb and depleted in all othe major, trace and rare earth elements (REE) relative to upper continental crust (UCC). The chondrite-normalized REE pattern shows a distinct negative slope for the LREEs and a slight negative slope for the HREEs with an enrichment of LREE/HREE of 8.11-10.90 and a negative Eu anomaly of 0.70-0.83. The most probable source of REEs is the heavy minerals detected in the sandstones. Tectonically, the studied rocks were derived from collision rifting arc-related settings. The Chemical Index of Alteration (CIA), Plagioclase Index of Alteration (PIA) and Index of Composition Variation (ICV) values of the Injana sandstones suggest that they are compositionally immature and suffered from very weak weathering indicating the proximity of their source rocks and their deposition under dry continental conditions.

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The stability of subducted glaucophane with the Earth’s secular cooling

Cited by 14 publications

References 68 publications

Diffusion Creep of Sodic Amphibole‐Bearing Blueschist Limited by Microboudinage

Diffusion Creep of Sodic Amphibole‐Bearing Blueschist Limited by Microboudinage

An introductory review of the thermal structure of subduction zones: I. Motivation and selected examples

Petrography and geochemistry of sandstones from the Injana Formation, Hemrin South Mountain, Northern Iraq: Implications for provenance, weathering and tectonic setting

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