start-ver=1.4 cd-journal=joma no-vol=127 cd-vols= no-issue=3 article-no= start-page=e2021JB023586 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=20223 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Deformation of Post‐Spinel Under the Lower Mantle Conditions en-subtitle= kn-subtitle= en-abstract= kn-abstract=To study the viscosity of bridgmanite and ferropericlase aggregate, uniaxial compression deformation experiments on pre-synthesized post-spinel phase and bridgmanite two-layered samples were conducted under top lower mantle pressure and 1773 K utilizing DT-Cup apparatus. Up to the strain of 0.25 ± 0.05, the observed comparable strain of the bridgmanite and post-spinel samples suggests the bridgmanite dominates the bulk viscosity of the post-spinel without strain localization in periclase. The microstructures of the deformed post-spinel samples show evidence of a similar strain of periclase with the bulk strain without strain partitioning. Texture analyses of bridgmanite indicate a dominant slip plane (100), with a steady state fabric strength achieved within the strain of 0.12 ± 0.01. The current experiment has provided no evidence about an onset of strain localization of ∼30 vol.% periclase at 0.25 strain. Our observations provide direct experimental verification of bridgmanite controlled rheology under low strain magnitude, which should be considered in geodynamical models which include mantle compositional and rheological evolution in the lower mantle. en-copyright= kn-copyright= en-aut-name=XuF. en-aut-sei=Xu en-aut-mei=F. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=YamazakiD. en-aut-sei=Yamazaki en-aut-mei=D. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=HuntS. A. en-aut-sei=Hunt en-aut-mei=S. A. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TsujinoN. en-aut-sei=Tsujino en-aut-mei=N. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=HigoY. en-aut-sei=Higo en-aut-mei=Y. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=TangeY. en-aut-sei=Tange en-aut-mei=Y. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=OharaK. en-aut-sei=Ohara en-aut-mei=K. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=DobsonD. P. en-aut-sei=Dobson en-aut-mei=D. P. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= affil-num=1 en-affil=Institute for Planetary Materials, Okayama University kn-affil= affil-num=2 en-affil=Institute for Planetary Materials, Okayama University kn-affil= affil-num=3 en-affil=Department of Earth Sciences, University College London kn-affil= affil-num=4 en-affil=Institute for Planetary Materials, Okayama University kn-affil= affil-num=5 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=6 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=7 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=8 en-affil=Department of Earth Sciences, University College London kn-affil= en-keyword=lower mantle kn-keyword=lower mantle en-keyword=rheology kn-keyword=rheology en-keyword=deformation kn-keyword=deformation en-keyword=post-spinel kn-keyword=post-spinel en-keyword=strain localization kn-keyword=strain localization END start-ver=1.4 cd-journal=joma no-vol=123 cd-vols= no-issue=5 article-no= start-page=3698 end-page=3728 dt-received= dt-revised= dt-accepted= dt-pub-year=2018 dt-pub=20185 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Production of High‐Sr Andesite and Dacite Magmas by Melting of Subducting Oceanic Lithosphere at Propagating Slab Tears en-subtitle= kn-subtitle= en-abstract= kn-abstract=We present K-Ar ages, major and trace element concentrations, and Sr-Nd-Pb isotope data for late Cenozoic volcanic rocks from the Chugoku district, southwest Japan arc. Andesite and dacite lavas in this region are enriched in Sr (mostly >800 μg g−1) and show geochemical characteristics of volcanic rocks commonly referred to as “adakite.” K-Ar dating of these lavas revealed that the eruption of high-Sr andesitic to dacitic magmas occurred during the last 2 Myr, following or concurrent with the eruption of basalt in adjacent regions. Trace-element characteristics of high-Sr andesites and dacites are consistent with the formation of their parent magmas by partial melting of the basaltic layer of the subducting Shikoku Basin Plate. Mass balance modeling of trace element concentrations and isotopic compositions suggests that the parental magmas of high-Sr andesites and dacites are best explained by mixing of partial melts from oceanic crust (F = 5–15%) and sediment (F = 30%) at 80:20 to 55:45 ratios. Spatial coincidence of the occurrences of high-Sr andesites and dacites and seismic gaps of the subducting slab demonstrates the causal link between slab melting and mantle upwelling at slab tears. We speculate that these tears could have been formed by subduction of ridges on the plate. A warm mantle upwelled through tears, preventing the solidification of the siliceous slab melts in the mantle and facilitating the transportation of these melts to the surface. en-copyright= kn-copyright= en-aut-name=Pineda‐VelascoI. en-aut-sei=Pineda‐Velasco en-aut-mei=I. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=KitagawaH. en-aut-sei=Kitagawa en-aut-mei=H. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=NguyenT. ‐T. en-aut-sei=Nguyen en-aut-mei=T. ‐T. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=KobayashiK. en-aut-sei=Kobayashi en-aut-mei=K. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=NakamuraE. en-aut-sei=Nakamura en-aut-mei=E. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University at Misasa kn-affil= affil-num=2 en-affil=Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University at Misasa kn-affil= affil-num=3 en-affil=Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University at Misasa kn-affil= affil-num=4 en-affil=Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University at Misasa kn-affil= affil-num=5 en-affil=Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University at Misasa kn-affil= en-keyword=adakite kn-keyword=adakite en-keyword=subduction zone kn-keyword=subduction zone en-keyword=slab melting kn-keyword=slab melting en-keyword=slab tear kn-keyword=slab tear END start-ver=1.4 cd-journal=joma no-vol=16 cd-vols= no-issue=9 article-no= start-page=2848 end-page=2852 dt-received= dt-revised= dt-accepted= dt-pub-year=2015 dt-pub=2015830 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Comment on “Diverse magmatic effects of subducting a hot slab in SW Japan: Results from forward modeling” by J.‐I. Kimura et al. en-subtitle= kn-subtitle= en-abstract= kn-abstract= en-copyright= kn-copyright= en-aut-name=Pineda‐VelascoIvan en-aut-sei=Pineda‐Velasco en-aut-mei=Ivan kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=NguyenTai T. en-aut-sei=Nguyen en-aut-mei=Tai T. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KitagawaHiroshi en-aut-sei=Kitagawa en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=NakamuraEizo en-aut-sei=Nakamura en-aut-mei=Eizo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Pheasant Memorial Laboratory, Institute for Study of the Earth's Interior, Okayama University kn-affil= affil-num=2 en-affil=Pheasant Memorial Laboratory, Institute for Study of the Earth's Interior, Okayama University kn-affil= affil-num=3 en-affil=Pheasant Memorial Laboratory, Institute for Study of the Earth's Interior, Okayama University kn-affil= affil-num=4 en-affil=Pheasant Memorial Laboratory, Institute for Study of the Earth's Interior, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=125 cd-vols= no-issue=10 article-no= start-page=e2019JB019143 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2020 dt-pub=202010 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Feedback of Slab Distortion on Volcanic Arc Evolution: Geochemical Perspective From Late Cenozoic Volcanism in SW Japan en-subtitle= kn-subtitle= en-abstract= kn-abstract=Southwest Japan is an island arc formed by subduction of the Philippine Sea (PHS) plate. The Quaternary magmatism in this region is characterized by eruptions of high-Sr andesites and dacites, considered to have been derived by melting of the PHS plate. The loci of these volcanoes spatially coincide with seismic discontinuities of the subducted PHS plate. Thus, the magmatism is interpreted as the result of slab melting at the plate tears. However, the processes that promote slab tearing remain unclear. In this study, we applied geochronological and geochemical analyses to late Cenozoic volcanic rocks in southwest Japan as tracers of slab morphology. Two different magma types, ocean-island basalt (OIB) and island-arc basalt (IAB), have occurred over 12 million years (Myr). These two magmas are attributed to different integrations of melts extracted from an originally fertile mantle; the OIBs from high temperature melt (1,300–1,400°C) were extracted at a depth of 40–80 km, whereas the IABs were extracted from a shallower, lower temperature region (30–60 km, 1,200–1,350°C). Secular change in Sr enrichment of IAB likely arose due to a transition of slab-derived fluids, incorporated into magmas as they formed, from water- to melt-dominant one. Progressive shallowing of the subducted PHS plate is responsible for secular change in the properties of slab-derived fluids as well as rollback of OIB volcanoes. Production of chemically variable magmas in the Chugoku district is the surface expression of distorting slab morphology by interaction between mantle and the subducting plate. en-copyright= kn-copyright= en-aut-name=NguyenTai Truong en-aut-sei=Nguyen en-aut-mei=Tai Truong kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=KitagawaHiroshi en-aut-sei=Kitagawa en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=Pineda‐VelascoIvan en-aut-sei=Pineda‐Velasco en-aut-mei=Ivan kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=NakamuraEizo en-aut-sei=Nakamura en-aut-mei=Eizo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University kn-affil= affil-num=2 en-affil=Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University kn-affil= affil-num=3 en-affil=Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University kn-affil= affil-num=4 en-affil=Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University kn-affil= en-keyword=subduction zone kn-keyword=subduction zone en-keyword=volcanism kn-keyword=volcanism en-keyword=mantle kn-keyword=mantle en-keyword=basalt kn-keyword=basalt en-keyword=slab kn-keyword=slab END start-ver=1.4 cd-journal=joma no-vol=127 cd-vols= no-issue=5 article-no= start-page=e2021JB023328 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=20220525 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Bilateral Heterogeneity in an Upwelling Mantle via Double Subduction of Oceanic Lithosphere en-subtitle= kn-subtitle= en-abstract= kn-abstract=Vietnam is a major field of Cenozoic volcanism in Southeast (SE) Asia. Two contrasting models have been proposed to explain the mantle upwelling and volcanism in this region; collision of the Indian and Eurasian continents or subduction of the Pacific or Indo-Australian oceanic lithosphere. To place constraints on the origin of the intraplate volcanism in SE Asia, new geochronological and geochemical data for Cenozoic basalts in Vietnam are presented. Based largely on Sr-Nd-Pb isotope systematics, it was found that the sources of basalts from Central and Southern Vietnam are chemically distinct forming a sharp boundary at 13.5°N. The basalts north of the boundary show isotopic features similar to Enriched Mantle type 2 (EM2) ocean island basalts. Whereas the basalts south of the boundary show isotopic features similar to Enriched Mantle type 1 (EM1) ocean island basalts. The EM1 and EM2 basalts display positive Sr anomalies and elevated Pb/Ce and Th/La ratios, respectively. Such features suggest the origins of the sources through the recycling of deeply-subducted crustal lithologies. Furthermore, subduction of dense oceanic lithosphere can induce a convecting cell in the upper mantle. Therefore, we suggest that the chemically different basalts from Central and Southern Vietnam represent the surface expression of melting in two different convecting cells, one is driven by subduction of the Pacific plate and the other by subduction of the Indo-Australian plate. en-copyright= kn-copyright= en-aut-name=DaoNghiem Van en-aut-sei=Dao en-aut-mei=Nghiem Van kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=KitagawaHiroshi en-aut-sei=Kitagawa en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=NakamuraEizo en-aut-sei=Nakamura en-aut-mei=Eizo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=KobayashiKatsura en-aut-sei=Kobayashi en-aut-mei=Katsura kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=NgoThanh Xuan en-aut-sei=Ngo en-aut-mei=Thanh Xuan kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=TrinhSon Hai en-aut-sei=Trinh en-aut-mei=Son Hai kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=2 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=3 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=4 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, kn-affil= affil-num=5 en-affil=Department of Geology, Hanoi University of Mining and Geology kn-affil= affil-num=6 en-affil=Vietnam Institute of Geoscience and Mineral resources kn-affil= en-keyword=intraplate volcanism kn-keyword=intraplate volcanism en-keyword=Sr-Nd-Pb isotopes kn-keyword=Sr-Nd-Pb isotopes en-keyword=EM1-EM2 basalts kn-keyword=EM1-EM2 basalts en-keyword=recycled crustal materials kn-keyword=recycled crustal materials en-keyword=subduction-induced mantle upwelling kn-keyword=subduction-induced mantle upwelling en-keyword=SE Asia kn-keyword=SE Asia END