 | | Journal (article/letter/editorial) | | Petrology of a chromitite micropod from Hess Deep, equatorial Pacific: a comparison between abyssal and alpine-type...the first report of podiform chromitite from the ocean floor. A micropod of chromitite, about 2 cm across...long, was found in dunite drilled from Hess Deep, equatorial Pacific, during ODP Leg 147. The pod is composed...dunite from Hess Deep sometimes have spinel disseminations. The chromitite micropod from Hess Deep, although...both chromitites. The spinel concentrations from Hess Deep were due to interaction between MORB and harzburgite |  | | Journal (article/letter/editorial) | | University, Kakuma, Kanazawa 920-l 1, Japan *Far East Geological Institute, 690022, Vladivostok 22, Russia...enriched with incompatible components were found in ocean-floor ultramafic-mafic plutonic rock suites recovered...contrasting ridge systems, i.e., the East Pacific Rise (Hess Deep, equatorial Pacific), a typical fast-spreading...formed through interaction between depleted mid-ocean ridge basalts (MORBs) and oceanic peridotite. Primary...inclusions are associated with albite, nepheline, jadeite, diopside, and orthopyroxene (Arai and Matsukage |  | | Journal (article/letter/editorial) | | chromian spine1 can be also formed under the mid-ocean ridge condition [2,3]. The inclusion was found in...micropod within dunite drilled from Hess Deep, equatorial Pacific (see plate l-5 of Ref. [2]). The minerals...(Na- and K-), pargasite, diopside, enstatite, jadeite, nepheline and albite; they are characterized by...slab [3]. I think from the evidence from both Hess Deep and Mid-Cayman Trough [3] that the concentration...this case). The melt trapped by the spine1 from Hess Deep is supposed to be also alkalic but its chemical |  | | Journal (article/letter/editorial) | | Shoji Arai Jadeite, albite and nepheline as inclusions in spinel of chromitite from Hess Deep, equatorial...consist of a few grains of diopside, enstatite, jadeite, nepheline, albite, pargasite, phlogopites and...spinel in a chromitite pod and in troctolite from Hess Deep, equatorial Paci®c. The inclusion mineral suite...characterized by Na-Al silicates, such as jadeite, nepheline and albite. Jadeite and nepheline commonly coexist...nepheline could also be formed at the magmatic stage. Jadeite was formed by a subsolidus reaction of albite and |  | Payot, Betchaida D., Arai, Shoji, Dick, Henry J. B., Abe, Natsue, Ichiyama, Yuji (2014) Podiform chromitite formation in a low-Cr/high-Al system: An example from the Southwest Indian Ridge (SWIR) Mineralogy and Petrology, 108 (4) 533-549 doi:10.1007/s00710-013-0317-z | Journal (article/letter/editorial) | | was from the ODP Leg 147 drilling in Hess Deep, equatorial Pacific, wherein a chromitite micropod about...because of the limited sampling of the current ocean floor (Arai 1997). Recent reassessment of abyssal...southern Atlantic Ocean to the Rodrigues Triple Junction (26°S, 70°E) in the Indian Ocean, it separates the...spreading segments oblique to the direction of ocean floor spreading and shorter near-orthogonal magmatic...m) compared to the oblique supersegment. Further east, the fourth subsection includes the 150 km long |  | | Journal (article/letter/editorial) | | Podiform chromitites do form beneath mid-ocean ridges Shoji Arai, Makoto Miura PII: DOI: Reference:...Makoto, Podiform chromitites do form beneath mid-ocean ridges, LITHOS (2015), doi: 10.1016/j.lithos.2015...MANUSCRIPT Podiform chromitites do form beneath mid-ocean ridges PT Shoji Arai* and Makoto Miura SC RI...have AC rarely been observed in the present-day ocean floor, even though some ophiolites are considered...apparent rarity of chromitites in the present-day ocean floor is SC RI simply a reflection of the under-sampling |  | Matsukage, K. N., Kikuchi, S., Ono, S., Nishihara, Y., Kikegawa, T. (2010) Density and seismic velocities of chromitite body in oceanic mantle peridotite. American Mineralogist, 95 (10) 1422-1428 doi:10.2138/am.2010.3498 | Journal (article/letter/editorial) | | Oman ophiolite was formed at a fast-spreading mid-ocean ridge system (e.g., Nicolas 1989). On the other...ophiolite and concluded that one was formed at a mid-ocean ridge and the other was formed at a subduction zone...2010.3498 oceanic peridotites from mid-ocean ridges and ocean floors, except for one rod-shaped mini-chromitite...about 2 cm across and 10 cm long from Hess Deep, East Pacific Rise (Arai and Matsukage 1996; Matsukage...formed at a mid-ocean ridge, we can find the chromitite at present mid-ocean ridges and/or ocean floor regions |  | | Journal (article/letter/editorial) | | inch furnace were calibrated using the albite ´ jadeite + quartz reaction at 600 ∞C, 1.63 GPa (Holland... a mantle section of the Oman ophiolite, East Pacific Rise peridotites, and Horoman peridotites (Matsukage...the mid-ocean ridges (America-Antarctic Ridge, Southwest Indian ridge and East pacific Rise) are after...pressures more than 1.0 GPa. Peridotites from mid-ocean ridges have been considered as good examples of...the mid-ocean ridges (America-Antarctic Ridge, Southwest Indian ridge and East Pacific Rise) are after |  | | Journal (article/letter/editorial) | | Montana, USA, 871 Beryllium, lithium and boron in ocean island basalts from French Polynesia: implications...carminite, 805 Boron, lithium and beryllium in ocean island basalts from French Polynesia: implications...W., 519 DUDOIGNON,P., 563 DUPUV, C., 563 East Pacific Rise, melt-peridotite interactions in shallow mantle...structure of, 897 FRATINI,F., 663 French Polynesian, ocean island basalts and their lithium, boron and beryllium...shallow mantle at the East Pacific Rise: evidence from ODP site 895 (Hess Deep), 191 HASSAN, I., 617 |  | Tseng, C.-Y., Yang, H.-Y., Wu, H.-Q., Zuo, G.-C. (2007) THE SILICATE MINERAL INCLUSIONS IN THE CHROMIAN SPINEL FROM THE DONGCAOHE OPHIOLITE, NORTH QILIAN MOUNTAINS, NORTHWESTERN CHINA: RECORD OF SYNTEXIS OF LOWER OCEANIC CRUST. The Canadian Mineralogist, 45 (4) 793-808 doi:10.2113/gscanmin.45.4.793 | Journal (article/letter/editorial) | | orthopyroxene, pargasite, aspidolite, nepheline, jadeite, plagioclase, platinum-group minerals, base-metal...The Dongcaohe ophiolite, a typical Caledonian mid-ocean-ridge type of ophiolite with an age of 497 ± 7 Ma... It is interpreted to have originated in a mid-ocean ridge or mature back-arc environment on the basis...standards. The following standards were used: jadeite (for Na), orthoclase (for K), SiO2 (for Si), Al2O3...1991), Hess Deep (Arai & Matsukage 1998), Oman ophiolite (Arai et al. 2004), Mid-Cayman Rise (Elthon |  | Tamura, Akihiro, Morishita, Tomoaki, Ishimaru, Satoko, Hara, Kaori, Sanfilippo, Alessio, Arai, Shoji (2016) Compositional variations in spinel-hosted pargasite inclusions in the olivine-rich rock from the oceanic crust–mantle boundary zone. Contributions to Mineralogy and Petrology, 171 (5) doi:10.1007/s00410-016-1245-9 | Journal (article/letter/editorial) | | inclusions in rock samples from the ocean floor near a mid-ocean ridge and trench. Pargasite is the dominant... because the crystallization sequence of a mid-ocean ridge basalt (MORB) melt involves first the crystallization...inclusions in olivine-rich rock samples from the ocean floor. Glass inclusions in spinel have been reported...olivine-rich rocks as well as in chromitites from the ocean floor and ophiolites, and the inclusions are composed...pargasite inclusions in olivine-rich rocks from the ocean floor. Taking into account the earlier data of Morishita |  | Rospabé, Mathieu, Ceuleneer, Georges, Le Guluche, Vanessa, Benoit, Mathieu, Kaczmarek, Mary-Alix (2021) The Chicken and Egg Dilemma Linking Dunites and Chromitites in the Mantle–Crust Transition Zone beneath Oceanic Spreading Centres: a Case Study of Chromite-hosted Silicate Inclusions in Dunites Formed at the Top of a Mantle Diapir (Oman Ophiolite) Journal of Petrology, 62 (4) doi:10.1093/petrology/egab026 | Journal (article/letter/editorial) | | interaction between an asthenospheric diapir (the mid-ocean ridge basalt source), and a colder, altered lithospheric...present in ophiolites that evolved in tholeiitic [mid-ocean ridge basalt (MORB)like] environments where they...1994; Allan & Dick, 1996; Borisova et al., 2012). Deep-seated dunites associated with mantle harzburgites...the original one). The cross-section sampling from deep to shallower levels with an interval of 10– 20 m...al., 2017; Wojtulek et al., 2019), in presentday ocean floor spinels in peridotites and chromitites (Arai |  | | Report (chapter) | | diversity and origin of ophiolites in Japan and Far East Russia with emphasis on depleted harzburgite AKIRA...Sciences, Pyzhevsky 7, Moscow 109017, Russia 3Far East Geological Institute, Russian Academy of Sciences...and Krasnaya (Koryak Mountains) ophiolites in Far East Russia, which have both depleted harzburgite and... and the Koryak Mountains in the northwestern Pacific margin have diverse ophiolite types ranging from...forearc environment. The ophiolites of Japan and Far East Russia range in age from Early Palaeozoic to Cenozoic |  | | Journal (article/letter/editorial) | | the subduction-related arc-type and/or MORB (mid-ocean ridge basalt)-like magmas are mainly responsible...found from the Pacific Ocean also contains subduction-related arc-type and/or MORB (mid-ocean ridge basalt)-like...[16,44–48]. The chromitite pod found from the Pacific Ocean also contains chromite with abundant solid inclusions...compositions of a nephelinite [56], averaged was mid-ocean ridge intrusion [13] and forlayered the Oman ophiolite...compositions a nephelinite [56], comparison. The mid-ocean range for possible magmas to the Stillwater complex |  | | Journal (article/letter/editorial) | | due to cooling along with hydration, which gave rise to a compositional variation of Ca-amphibole, from...Seamount with the mid-ocean ridge peridotite from Hess Deep, near the East Paci®c Rise (e.g. Arai and Matsukage...plan, being 50 km from south to north by 10 km from east to west (Fig. 1). The ¯at summit is ~1200 m below...grain size of spinel, with Cr# of 0.5, in the Hess Deep harzburgite and dunite (Fig. 5b). Amphiboles are...in (Na + K) and Al in the ultrama®c rocks from Hess Deep (Fig. 6). Genesis of the Hahajima peridotite |  | Akizawa, Norikatsu, Miyake, Akira, Ishikawa, Akira, Tamura, Akihiro, Terada, Yasuko, Uesugi, Kentaro, Takeuchi, Akihisa, Arai, Shoji, Tanaka, Chima, Igami, Yohei, Suzuki, Katsuhiko, Kogiso, Tetsu (2017) Metasomatic PGE mobilization by carbonatitic melt in the mantle: Evidence from sub-μm-scale sulfide–carbonaceous glass inclusion in Tahitian harzburgite xenolith. Chemical Geology, 475. 87-104 doi:10.1016/j.chemgeo.2017.10.037 | Journal (article/letter/editorial) | | of the French Polynesian Archipelago in the Pacific Ocean (Fig. 1). The Society Islands form linear MA...comparison with oceanic harzburgites collected in mid-ocean ridges, the H3-001_TK ED harzburgite is greatly...end-member components; kosmochlor (NaCrSi2O6), jadeite (NaAlSi2O6) and aegirine (NaFe3+Si2O6) (Table 3)...gabbro-troctolite-peridotite complex from Hess Deep, equatorial Pacific: implications for mantle-melt interaction...Mayer, P.S. (Eds.), Scientific Results. vol. 147, Ocean Drilling Program, Texas A&M University, College |  | | Journal (article/letter/editorial) | | that shown by olivines in hydrothermally altered ocean-floor gabbros. The eclogitic gabbros are hydrous...similarity of olivine alteration patterns to those of ocean-floor gabbros suggests that hydration and local...high-temperature ocean-floor alteration. The preservation of magmatic and hydrothermal d18O values in ocean-floor...GPa (60–75 km) implies that the deeper levels of ocean crust have not experienced pervasive fluid flow...Messiga & Scambelluri, 1988). Petrographic studies of ocean-floor gabbros have shown that partial hydration |  | | Journal (article/letter/editorial) | | and depleted residual harzburgite beneath the mid-ocean ridge spreading center. The trace-element compositions...the dunite, troctolite and chromitite from the ocean floor and the ophiolite (e.g., Lorand and Cottin...et al. 2008; Morishita et al. 2011b). From the ocean floor, dunite and troctolite are often collected...and depleted residual harzburgite beneath the mid-ocean ridge spreading center (Suhr et al. 2008; Tamura...and MAR 30°N (Blackman et al. 2004). Integrated Ocean Drilling Program (IODP) Expedition 304/305 recovered |  | | Report (issue) | | terrane (after Rawling, 1998). At 55 Ma the Lord Howe Rise (LHR) and Norfolk Ridge (NR) continental slivers...Kristin A. Ebert Thermal evolution and exhumation of deep-level batholithic exposures, southernmost Sierra...Tertiary plate boundary processes in the southwest Pacific ..........-- 22, Suzanne L. Baldwin, Timothy Rawling...indicated, which is interpreted as due to buoyant rise up the subduction zone after continental collision...continental crust (the “upper plate”) during low-angle, east-dipping subduction related to the Laramide orogeny |  | | Book | | Spreading Centers of the Easter Micropiate (South East Pacific) M. Constantin, R. Hekinian, D. Ackermand and...magmatic and tectonic processes which affected these deep zones of the ridge. Obviously, magmatic and tectonic...no manifestly cyclic activ- 2 ity. Exposure of deep rocks in such cases is much more limited as in the...probably a predecessor of the fast-spreading East Pacific Rise. Eventually, the volume closes with a numerical...the building of the lower crust at magma-starved ocean ridges, This model involves successive stages of |  | Morishita, Tomoaki, Maeda, Jinichiro, Miyashita, Sumio, Kumagai, Hidenori, Matsumoto, Takeshi, Dick, Henry J.B. (2007) Petrology of local concentration of chromian spinel in dunite from the slow-spreading Southwest Indian Ridge. European Journal of Mineralogy, 19 (6) 871-882 doi:10.1127/0935-1221/2007/0019-1773 | Journal (article/letter/editorial) | | spinel, chromitite, dunite, slow-spreading ocean-ridge, ocean floor, melt-mantle interaction. Introduction...flow likely occurs in the shallow mantle beneath ocean ridges (Dick, 1989). The average abyssal peridotite...peridotite sampled from an ultraslow spreading ocean ridge representing a key end-member for seafloor...sample was collected. The site Hole 735B of the Ocean Drilling Program is also shown. ple, from the Atlantis...km offset of the SWIR (Fig. 1). Hole 735B of the Ocean Drilling Program (Legs 118 and 176) succeeded in |  | | Journal (article/letter/editorial) | | processes, including the peridotite-magma reaction, deep-seated magmatic evolution, and mantle dynamics....some are of the mid-ocean ridge type; ED chromitites may be common beneath the ocean floor, although it...associated with chemical alteration, which gives rise to even more complicated modes of AC occurrence...that chromite in a micropod of chromitite from Hess Deep, EPR, contains similar inclusions of hydrous minerals...magma-producing tectonic setting, i.e., arc, mid-ocean ridge or intra-plate (e.g., Arai, 1992, 2011). The |  | | Journal (article/letter/editorial) | | 69(6), pp. 1059±1075 Kosmochlor and chromian jadeite aggregates from the Myanmar jadeitite area G. H...related compositions of kosmochlor (Ko) and chromian jadeite in rocks from the Myanmar jadeitite area are described:...spheroidal or ellipsoidal aggregates with a core of jadeite; (3) granoblastic textures in undeformed coarse-grained...compositional boundaries between kosmochlor and chromian jadeite of variable composition are interpreted to be related...compositions analysed plot along the kosmochlor-jadeite join. In contrast to conclusions of previous studies |  | | Journal (article/letter/editorial) | | repre senting the Jurassic crust of the Piemonte ocean destroyed in the Alpine orogeny, are preserved in...material also are present in the Tauern window farther east. Three major nappes piled one above the other and...metaperidotite were likely derived from the breakdown of ocean-floor Cl-bearing serpentine and brucite pseudomorphing...analysis performed on pyroxene separates (augite in ocean gabbro and omphacite in high-pressure metagabbro)...samples from the Alps and the hydrothermally altered ocean floor and ophiolites. All eclogitic metagabbros |  | | Report (chapter) | | activity proceeding on grain boundaries within the deep oceanic crust at very high temperatures (900– 1000...Oman) as well as on recent oceans (equatorial Pacific) focus on the transition zone between gabbro and...2004). Since seawater– rock interactions in the deep-ocean crust at very high temperatures have been reported...example of hydrous partial melting in gabbros in the deep oceanic crust, providing the opportunity to investigate...spreading and the geodynamics of fastspreading mid-ocean ridges (e.g. Gregory & Taylor 1981; Pallister & |
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