Ultramafic tectonite of the Miyamori ophiolitic complex in the Kitakami Mountains, Northeast Japan: hydrous upper mantle in an island arc

Ozawa, Kazuhito

doi:10.1007/bf00371458

Cited by 76 publications

(71 citation statements)

References 71 publications

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“…1). Peridotites in this complex are extensively serpentinized (mostly containing >60 vol% serpentine; Ozawa, 1988). The tectonite members are divided into two suites on the basis of spinel Cr -number [Cr# = 100 × Cr/(Cr + Al)]: aluminous spinel ultramafic suite (ASUS; Cr# <40) and chromite -bearing ultramafic suite (CSUS; Cr# >40; Ozawa, 1988).…”

Section: Petrological Backgrounds and Samplementioning

confidence: 99%

“…The tectonite members are divided into two suites on the basis of spinel Cr -number [Cr# = 100 × Cr/(Cr + Al)]: aluminous spinel ultramafic suite (ASUS; Cr# <40) and chromite -bearing ultramafic suite (CSUS; Cr# >40; Ozawa, 1988). The ASUS occurs as kilometerscale patches in the CSUS in the Miyamori complex and is widely distributed in the Hayachine complex (e.g., Ozawa, 1988). A peculiar feature of the refractory harzburgite in the HM complex is the presence of primary amphibole, indicating influx of a hydrous agent (Ozawa, 1988).…”

Section: Petrological Backgrounds and Samplementioning

confidence: 99%

“…The ASUS occurs as kilometerscale patches in the CSUS in the Miyamori complex and is widely distributed in the Hayachine complex (e.g., Ozawa, 1988). A peculiar feature of the refractory harzburgite in the HM complex is the presence of primary amphibole, indicating influx of a hydrous agent (Ozawa, 1988). A fresh harzburgite boulder (73003; 60 cm across) was found within the CSUS area of the Miyamori complex between the Sarugaishi and Otomo Rivers, approximately 1 km from the Hizume -Kesennuma Fault (Ozawa, 1988).…”

Section: Petrological Backgrounds and Samplementioning

confidence: 99%

“…The Hayachine -Miyamori (HM) ophiolitic complex in northeast Japan is suggested to have formed by open -system melting rather than metasomatism after partial melting on the basis of systematic changes of geochemical and modal compositions, and occurrence of primary amphiboles even in highly residual harzburgite (e.g., Ozawa, 1988;Ozawa and Shimizu, 1995). The chondrite -normalized trace element variation examined with open -system melting models (Ozawa, 2001) suggests that three distinct influx agents, which originated from various slab -derived components, were involved in the partial melting (Yoshikawa and Ozawa, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Geochemical and Os isotopic characteristics of a fresh harzburgite in the Hayachine-Miyamori ophiolite: Evidence for melting under influx of carbonate-rich silicate melt in an infant arc environment

Yoshikawa

Suzuki

Shibata

et al. 2012

Journal of Mineralogical and Petrological Sciences

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Os isotopic composition ( 187Os/ 188 Os = 0.1235) of a refractory harzburgite in the Hayachine -Miyamori ophiolite is subchondritic, indicating the long -term depletion of Re. Such an unradiogenic Os isotopic signature is consistent with the less oxidized condition at subduction initiation. The major and trace element characteristics of the harzburgite, together with its petrography and relatively high modal abundance of clinopyroxene, suggest an involvement of a carbonate -rich silicate melt during melt extraction in arc setting.

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Section: Petrological Backgrounds and Samplementioning

confidence: 99%

Section: Petrological Backgrounds and Samplementioning

confidence: 99%

Section: Petrological Backgrounds and Samplementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Geochemical and Os isotopic characteristics of a fresh harzburgite in the Hayachine-Miyamori ophiolite: Evidence for melting under influx of carbonate-rich silicate melt in an infant arc environment

Yoshikawa

Suzuki

Shibata

et al. 2012

Journal of Mineralogical and Petrological Sciences

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“…CaCa-NaNa- Ishizuka, 1980Ishizuka, , 1987 Na Type 2 Na K , Ozawa, 1988;Ohara and Ishii, 1998;Zanetti et al, 1999;Chen and Zeng, 2007;Spandler et al, 2008 Khedr andArai 2009 , Na Evans, 1977Arai, 1975, 1984;Nozaka, 2003Nozaka, , 1951Fujimaki and Yomogida, 1986 …”

mentioning

confidence: 99%

飛騨外縁帯，小滝地域の超苦鉄質岩：大江山オフィオライトかんらん岩とその変成作用について

澄秋

明

2010

Jour. Geol. Soc. Japan

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Serpentinite hornfelses that formed by later contact metamorphism vary in their mineral assemblages, defined by atg, ol cpx, ol tr, ol tr talc, and ol tr opx zones that are arranged from west to east. The zones indicate that metamorphic temperatures generally increased toward the east. This finding suggests that the hornfelsic metamorphism of previously serpentinized peridotites of Type and Type was caused by a concealed plutonic intrusion beneath the Ishizaka rhyolite, which is exposed to the east. Abstract

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Genesis and tectonic implications of cumulate pyroxenites and tectonite peridotites from the Nagaland–Manipur ophiolites, Northeast India: constraints from mineralogical and geochemical characteristics

et al. 2016

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The Nagaland–Manipur ophiolites (NMO) of Northeast India forms a part of the Tethyan ophiolites and comprises a suite of tectonite peridotites and cumulate mafic–ultramafic sequence with mafic extrusive–intrusive rocks, felsic intrusives and oceanic pelagic sediments along with minor podiform chromitites. However, sheeted dykes, which are considered as a significant component of ophiolites, are absent in the NMO. The tectonite peridotites are distinguished from the cumulate pyroxenites by the presence of pyroxene lineation, deformed bands and strained extinction in olivine, kink twin lamellae in pyroxene. Both the tectonite peridotites and cumulate pyroxenites contain aluminous spinel with Cr number [Cr# = Cr/(Cr + Al)] in the range of 0.14 to 0.29 and 0.27 to 0.48, respectively. Mg number [Mg# = Mg/(Mg + Fe2+)] in Cr‐spinel is higher in tectonite peridotites (0.71–0.76) than cumulate pyroxenites (0.44–0.53). Chondrite‐normalized rare earth elements (REE) patterns of cumulate pyroxenites exhibit depleted at light REEE (LREE) (LaN/SmN = 0.380–0.759) but flat middle REE (MREE) to heavy REE (HREE) (SmN/YbN = 0.622–0.756). However, the tectonite peridotites show gradual decrease in concentrations from HREE to MREE (SmN/YbN = 0.285–0.460) and slight increase in LREE (LaN/SmN = 0.721–2.201). The cumulate pyroxenites show strong enriched PPGE patterns and higher PGE concentrations (∑PGE = 85.8–163.5 ppb) compared with the tectonite peridotites (∑PGE = 34.8–113.0 ppb). The estimated equilibration temperature ranges from 890 to 931 °C for cumulate pyroxenites and 971 to 1156 °C for tectonite peridotites. The olivine–spinel equilibrium along with Cr‐spinel chemistry and PGE data suggests that the tectonite peridotites represent the residual mantle left after limited extraction of basaltic melts by low‐degree partial melting (<15%). Conversely, the presence of highly magnesian orthopyroxene and clinopyroxene in the cumulate pyroxenites in conjunction with their geothermometry suggests that they were formed at high pressure and temperature by magmatic fractionation from the basaltic melt. The geochemical data together with field and petrographical evidences indicate that both the tectonite peridotites and cumulate pyroxenites are essentially spinel‐bearing and devoid of plagioclase, suggesting their derivation in the mantle beyond the stability limit of plagioclase in a mid‐oceanic ridge tectonic setting. We conclude that the ultramafic sequence of the NMO was initially generated at a mid‐oceanic ridge tectonic setting close to the eastern boundary of the Indian passive margin and then thrust over the continental margin of the Indian Plate towards the west during its collisional and subduction process with/beneath the Myanmar Plate. Copyright © 2016 John Wiley & Sons, Ltd.

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Ultramafic tectonite of the Miyamori ophiolitic complex in the Kitakami Mountains, Northeast Japan: hydrous upper mantle in an island arc

Cited by 76 publications

References 71 publications

Geochemical and Os isotopic characteristics of a fresh harzburgite in the Hayachine-Miyamori ophiolite: Evidence for melting under influx of carbonate-rich silicate melt in an infant arc environment

Geochemical and Os isotopic characteristics of a fresh harzburgite in the Hayachine-Miyamori ophiolite: Evidence for melting under influx of carbonate-rich silicate melt in an infant arc environment

飛騨外縁帯，小滝地域の超苦鉄質岩：大江山オフィオライトかんらん岩とその変成作用について

Genesis and tectonic implications of cumulate pyroxenites and tectonite peridotites from the Nagaland–Manipur ophiolites, Northeast India: constraints from mineralogical and geochemical characteristics

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