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Geology; March 2008; v. 36; no. 3; p. 219-222; DOI: 10.1130/G24350A.1
© 2008 Geological Society of America
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Forearc diamond from Japan

T. Mizukami1, S. Wallis1, M. Enami1 and H. Kagi2

1 Department of Earth and Planetary Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8602, Japan
2 Geochemical Laboratory, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 GEOLOGY AND PETROLOGY
 RAMAN ANALYSES
 PRESSURE-TEMPERATURE EVOLUTION
 DISCUSSION
 CONCLUSIONS
 REFERENCES CITED
 
Convergent margins are not generally considered to be suitable places for the formation of diamond and its transport to Earth's surface. Microdiamonds found in xenoliths within a lamprophyre dike in southwest Japan show that this assumption is incorrect and, furthermore, that diamond occurs in a wider range of geological settings than previously realized. Petrological constraints show that these diamond-bearing minerals rose from depths of around 160 km (~5.5. GPa) and cooled from temperatures of ~1500 °C. The location of the diamond-bearing rocks in the forearc and close to the subducting plate requires the existence of mantle up-flow, which brought the diamond to shallow mantle levels before traveling 100-km-scale horizontal distances. If the dimensions of this flow are large, it can help explain both forearc magmatism and perhaps the development of subduction zones hot enough to melt sediments.

Key Words: diamond • forearc • mantle flow • micro-Raman spectroscopy


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
GEOLOGY AND PETROLOGY
 RAMAN ANALYSES
 PRESSURE-TEMPERATURE EVOLUTION
 DISCUSSION
 CONCLUSIONS
 REFERENCES CITED
 
Diamond formation requires high pressures and relatively low temperatures. Old, continental regions with thick relatively cool mantle roots and low geotherms are well-suited for these conditions and constitute the major location for diamond production. In these areas, diamonds are generally brought to Earth's surface in explosive volcanic eruptions, typically with a kimberlite matrix. Mantle close to subduction zones of convergent plate margins is also relatively low temperature and associated with volcanism. However, convergent-margin volcanism is not generally thought to be a suitable host for diamond. One reason why the occurrence of diamond in such volcanic rocks is unlikely is that associated magma originates at depths that are too shallow for diamond formation. In addition, the interaction between mantle and subducted materials produces relatively oxidized mantle (Parkinson and Arculus, 1999; Wood et al., 1990), which is also unsuitable for diamond formation. If oxidizing conditions prevail, carbon exists as CO2 or carbonate minerals and not diamond. In contradiction to these predictions, our studies reveal a natural occurrence of diamond in forearc volcanic rocks of southwest Japan. This is the first reported natural occurrence of diamond from the Japanese islands, and it shows that diamond occurs in a wider range of geological settings than previously realized. The location of the diamond-bearing rocks has major implications for the type of mantle flow that can be proposed in southwest Japan and convergent margins in general.


   GEOLOGY AND PETROLOGY
TOP
 ABSTRACT
 INTRODUCTION
 GEOLOGY AND PETROLOGY
RAMAN ANALYSES
 PRESSURE-TEMPERATURE EVOLUTION
 DISCUSSION
 CONCLUSIONS
 REFERENCES CITED
 
The Japanese diamond is hosted by a lamprophyre dike in Shikoku Island, Japan (Goto and Arai, 1987; Takamura, 1973), which has a K-Ar age of 17.7 ± 0.5 Ma (Uto et al., 1987). The dike is part of the widespread Cenozoic magmatism of southwest Japan that began ca. 25 Ma. This magmatism coincided with the rifting of the Japanese islands away from eastern Asia and the formation of the Sea of Japan back-arc basin (Kimura et al., 2003). The associated volcanic rocks have very variable geochemical characteristics and include significant amounts of high-magnesian basalt, alkali basalt, and both I- and S-type felsic rocks (Kimura et al., 2003; Takamura, 1973) (Fig. 1). Many of the alkali basalt rocks contain mantle xenoliths (Arai et al., 2005). There is considerable variation in the types of mantle xenoliths found in southwest Japan (Arai et al., 2005). Geochemical studies of the host rocks have been used to suggest a deep-mantle origin for some of the magma (Nakamura et al., 1989), but no petrological evidence of formation in the garnet lherzolite facies has been found.


Figure 01
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  		Figure 1. Cenozoic igneous activity in southwest Japan up to 4 Ma (after Kimura et al., 2003; Yamaji and Yoshida, 1998). Location of host lamprophyre in Shikoku Island is marked with star symbol. Distribution of Cretaceous to Tertiary Shimanto accretionary complex is also shown.

 
The host rock for the diamond-bearing pyroxene grains is a lamprophyre dike that has significant amounts of primary carbonate and biotite in the matrix (Goto and Arai, 1987). Abundant mantle xenoliths are included in the mafic matrix. These xenoliths consist mainly of peridotite associated with pyroxenite and xenocrysts of pyroxene (Goto and Arai, 1987). Microstructures in the peridotite xenoliths show a transition between plagioclase and spinel lherzolite facies (Goto and Arai, 1987), suggesting recrystallization at relatively shallow mantle depths of around 35 km, just below the base of the crust. Two distinct types of clinopyroxene are present. Type 1 is green in hand specimen and light green to brown in thin section and shows purplish anomalous interference colors under crossed polars. Type 2 is black in hand specimen and brown under the microscope. Both types of pyroxene contain CO2-dominant fluid inclusions. However, the inclusions in type 1 pyroxene are associated with cracking parallel to the cleavage planes. Microcrystals of diamond (Fig. 2A) occur within these inclusions completely enclosed by type 1 pyroxene. We have identified three grains of diamond in two distinct mantle xenoliths.


Figure 02
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  		Figure 2. A: Photomicrograph of clinopyroxene showing diamond-bearing inclusions. Characteristic spindle or lemon-fruit shapes of inclusions are result of expansion of fluid during decompression and splitting of host mineral along cleavage plane. B: Raman spectrum for diamond-bearing inclusion showing wave numbers characteristic of diamond, CO2 gas, a carbonate mineral, a hydrous mineral, and host clinopyroxene (cpx). Diamond is identified both by strong peak at a wave number of 1331 cm–1 and three regions of photolumi-nescence (marked as PL), all characteristic of diamond.

 
Mineral compositions of the pyroxene hosting the diamond were measured using a microprobe (JXA-8900R, JEOL) with an accelerating voltage and beam current of 15 kV and 12 nA, respectively. Representative analyses are given in Table 1. The pyroxene has a more aluminous and chromium-poor composition than pyroxene typically associated with spinel or plagioclase peridotite. These chemical features indicate a relatively high-temperature origin and are comparable to the clino pyroxene from the Beni Boussera Massif, a major European body of exposed mantle rock that contains graphite pseudomorphs after diamond in garnet pyroxenite layers (Davies et al., 1993).


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  		TABLE 1. CHEMICAL COMPOSITION OF CLINOPYROXENES INCLUDING DIAMONDS

 

   RAMAN ANALYSES
TOP
 ABSTRACT
 INTRODUCTION
 GEOLOGY AND PETROLOGY
 RAMAN ANALYSES
PRESSURE-TEMPERATURE EVOLUTION
 DISCUSSION
 CONCLUSIONS
 REFERENCES CITED
 
Raman spectroscopy is a nondestructive method that can be used to investigate properties of material enclosed in a transparent host. We used a Raman spectrometer, Nicolet Almega XR (Thermo Scientific) with a 532 nm Nd YAG laser, to study the mineral and fluid species present within completely enclosed inclusions. The Raman spectrum for the inclusion shows several peaks at key wave numbers characteristic of diamond, gaseous CO2, Ca-Mg carbonate mineral (probably dolomite), and hydrous minerals (Fig. 2B). We were not able to further identify the hydrous minerals. Diamond is identified both by its characteristic Raman shift and by photoluminescence bands (Fig. 2B). These photoluminescence bands, which are indicated by the letters ‘PL’ on the spectrum (Fig. 2B), are attributable to lattice defects in diamonds involving nitrogen impurities and vacancies and are characteristics of natural diamonds (Kagi et al., 2007). The relative weakness of the signals compared to millimeter-sized samples of diamond (from Mir Kimberlite pipe, Yakutia, Siberia) indicates that the diamond volume is smaller than the spatial resolution of the Raman analysis, an upright ellipsoid of 1 µm x 2 µm. Three-dimensional Raman mapping with a vertical resolution of ~2 µm demonstrates that the inclusions are not exposed on the surface of the sample (Fig. 3), and the presence of diamond cannot be explained as due to secondary contamination during sample preparation. The diamond is, therefore, a primary inclusion phase.


Figure 03
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  		Figure 3. Three-dimensional Raman analyses of diamond-bearing inclusion. A: Depth profile across diamond-bearing inclusions. Location of peak corresponding to diamond occurs within clinopyroxene (cpx). Schematic cross section shows location of other identified minerals and CO2 gas (see key sketch in part B). B: Areal mapping showing distribution of various minerals and CO2 gas within an inclusion. Diamond is in contact with carbonate and a hydrous mineral. Scale bars are 2µm.

 
Mapping using characteristic wave numbers shows that most of the inclusion is occupied by CO2 gas (Fig. 3). The original high residual pressure has now, in part, been released by fracturing of the surrounding clinopyroxene along cleavage planes, resulting in a spindle or lemon-fruit shape to the inclusions (Fig. 2A). The diamond is in contact with both the carbonate and hydrous minerals (Fig. 3).


   PRESSURE-TEMPERATURE EVOLUTION
TOP
 ABSTRACT
 INTRODUCTION
 GEOLOGY AND PETROLOGY
 RAMAN ANALYSES
 PRESSURE-TEMPERATURE EVOLUTION
DISCUSSION
 CONCLUSIONS
 REFERENCES CITED
 
We can use the phases in the inclusions and the composition of the host pyroxene to estimate the pressure-temperature (P-T) conditions when the diamond formed. Changes in the characteristic Raman signals at different depths in the sample show that a grain of dolomite exists between the diamond and the wall of the CO2-rich fluid inclusion (Fig. 3A). This micro-structural relation suggests that the formation of diamond occurred in the presence of dolomite. The stability for the diamond-CO2-clinopyroxene-dolomite assemblage is near the reaction curve of dolomite + coesite = diopside + CO2, around 5.5 GPa (150–170 km) and above 1400 °C (Fig. 4). The minimum temperature and pressure are compatible with the presence of partial melt in the CaO-MgO-Al2O3-SiO2 (CMAS)-CO2 system that is representative of the mantle (Fig. 4).


Figure 04
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  		Figure 4. Phase diagram for CaO-MgO-Al2O3-SiO2 (CMAS)-CO2 system and inferred pressure-temperature (P-T) path of diamond-bearing materials. Location of reaction curves is taken from literature (Kennedy and Kennedy, 1976; Luth, 1995; Luth, 2001; Presnall et al., 2002). Pl—plagioclase; Spl—spinel; Grt—garnet; Di—diopside; En—enstatite; Fo—forsterite; Coe—coesite; Mgs—magnesite; Dol—dolomite; Arg—aragonite. Thermodynamic calculations verify that chemical compositions of clinopyroxene and dolomite have minor effects on curve of Dol + Coe = Di + CO2.

 
The rim compositions of minerals that make up the xenoliths can be used to constrain another part of the P-T conditions experienced by peridotite xenoliths during their ascent entrained within the magma. Geothermometry using Fe2+-Mg exchange between orthopyroxene and clinopyroxene and microtextural evidence for coexistence of plagioclase and spinel in lherzolite provide rough estimates for reequilibration at around 1000 °C and pressures of ~1 GPa (Goto and Arai, 1987) (Fig. 4).


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 GEOLOGY AND PETROLOGY
 RAMAN ANALYSES
 PRESSURE-TEMPERATURE EVOLUTION
 DISCUSSION
CONCLUSIONS
 REFERENCES CITED
 
A major geological problem posed by the presence of diamond-bearing rocks in southwest Japan is how they rose from the depths required for their formation. At the present-day, subduction of the Philippine Sea plate is occurring at a depth of ~35–40 km (Shiomi et al., 2004) directly below the diamond locality. This depth is compatible with the second stage of reequilibration recorded in the xenoliths, but it is much too shallow for diamond stability. The subducting Philippine Sea plate forms a barrier to magma rising from greater depths, so how did the diamond find its way to the shallow mantle beneath southwest Japan?

Plate reconstructions show that this region has been the site of subduction since the Mesozoic (Engebretson et al., 1985; Maruyama et al., 1997; Sdrolias et al., 2004). This implies that a barrier to magma rising vertically from great depths has existed in this area for geologically long periods of time. There have, however, been several changes in the identity of the subducting plate (Maruyama et al., 1997; Sdrolias et al., 2004), and these switches in the subducting plate may represent opportunities for mantle to rise from deep levels. To understand if there was a barrier to the vertical rise of diamond-bearing mantle from directly beneath the lamprophyre dike at the time of its formation, it is important to constrain the onset of subduction of the Philippine Sea plate. One of the best constraints is the age of the formation of the Sea of Japan: opening of this basin requires plate convergence and subduction on its southern margin. The Sea of Japan began to open around 30 Ma and was largely complete by 12 Ma (Jolivet et al., 1994). The dike has an age of 17.7 Ma and was, therefore, intruded during this opening and associated subduction. Another change that has occurred since intrusion of the dike is that the accretionary prism of southwest Japan has grown southward and caused a corresponding shift in location of the subducting plate boundary to the south away from the intrusion. This implies that the diamond-bearing dike originally formed even closer to the subducting slab than its present location suggests. Large changes in the dip of the subduction zone are unlikely because the relatively young and buoyant oceanic plate was and still is being subducted. These considerations imply that there was not sufficient thickness of mantle wedge above the subducting slab to explain the formation of diamond directly beneath the present location.

We conclude the diamond-bearing mantle rocks rose from 150 km or more and were emplaced in shallow mantle levels in some region far away from their present position. The most plausible region is the back-arc region where there is a direct path to deep mantle regions. To reach their present position, the diamond-bearing rocks must then have undergone large-scale horizontal transport before being finally incorporated in a magma that rose to Earth's surface.

Large-scale, solid-state horizontal flow in the wedge mantle above subducting plates (Andrews and Sleep, 1974; Kneller et al., 2005) is commonly incorporated in thermal models of subduction zones. This flow is driven by the traction exerted on the overlying mantle by the down-going slab and results in the transport of mantle rock and heat toward the relatively cool downgoing oceanic slab. In models where this flow is incorporated, it is one of the most important factors controlling the temperatures in subduction zones. The magnitude of this effect depends strongly on the depth of mantle involved in the flow. However, this depth is disputed. Heat flow (Furukawa, 1993) and seismic data (Abers et al., 2006) suggest that flow in the mantle wedge, driven by strong coupling between the downgoing slab and the overlying mantle, begins at a depth of ~70 –80 km (Abers et al., 2006; Furukawa, 1993). Other workers have suggested that the induced flow in the mantle wedge could be as shallow as 35 km (Iwamori, 2000). There is no good observational evidence in support of flow at such shallow levels. However, this suggestion does have one big attraction: it produces models that are considerably hotter than models that do not incorporate induced flow or only include it starting at greater depths. Hot subduction zones are needed to explain a major problem in our understanding of the thermal evolution of subduction zones. Many petrological studies suggest that subduction zones should be hot enough to cause melting of subducted rocks beneath volcanic arcs (Elliot, 2003), whereas the results of standard thermal modeling suggest that such temperatures are very difficult to achieve (Peacock, 1996). If the diamond-bearing rocks reported here were transported into the corner of the wedge mantle as part of a large-scale flow, this would imply that induced flow reaching up to very shallow levels is occurring in the mantle wedge. This implies the presence of 100-km-scale horizontal flow of the mantle wedge passing beneath the volcanic arc. Such flow is predicted by recent thermo-mechanical models of convergent margins (Gerya and Stöckhert, 2006). A hot mantle at depths of 35 km helps to warm the entire subduction zone and implies that thermal models at the high-temperature end of the range of possibilities are appropriate for the southwest Japan convergent margin.

Southwest Japan experienced a widespread phase of Miocene magmatism, including much that was close to the subduction boundary in the forearc region (Fig. 1). Forearc magmatism is rare and usually thought to be related to the subduction of a very young oceanic plate or a spreading ridge (Forsythe et al., 1986). The same relationship has been proposed for the Miocene igneous activity of southwest Japan (Maruyama et al., 1997; Underwood et al., 1992). Our discovery suggests an alternative: heating in southwest Japan was caused by horizontal inflow of hot mantle that had originally risen from depths in excess of ~150 km in the back-arc region.


   CONCLUSIONS
TOP
 ABSTRACT
 INTRODUCTION
 GEOLOGY AND PETROLOGY
 RAMAN ANALYSES
 PRESSURE-TEMPERATURE EVOLUTION
 DISCUSSION
 CONCLUSIONS
REFERENCES CITED
 
Diamonds associated with CO2-rich fluid inclusions in clinopyroxene crystals occur in a Cenozoic lamprophyre dike in southwest Japan. This is the first reported natural occurrence of diamond from the Japanese islands. The newly discovered diamonds are located in the forearc region of southwest Japan, and this represents a previously unrecognized geological setting for diamond. Our detailed three-dimensional Raman analyses detected the Raman and photoluminescence signals characteristic of diamond and confirm that diamonds are completely enclosed within host pyroxene. Petrological analysis suggests that the diamonds and host minerals originated at depths of 150–170 km and temperatures of around 1500 °C. Our finding of microdiamonds in a forearc setting implies that this mineral occurs in a greater variety of geological settings than previously recognized.

The diamond-bearing rocks from the forearc mantle are direct evidence that deep-seated mantle up-flow can reach the shallowest levels of the mantle wedge adjacent to subduction boundaries. This inflow of hot mantle is a possible explanation for the Cenozoic thermal event of southwest Japan that caused widespread magmatic activity. Because subducting oceanic lithosphere would act as a barrier to a plume directly below the Japanese forearc, we suggest that the diamond-bearing mantle rose in the back-arc region before becoming incorporated in the mantle wedge. This implies the presence of 100-km-scale, subhorizontal mantle flow beneath arcs.


   ACKNOWLEDGMENTS
 
T. Mizukami acknowledges supports from the Japanese Society for the Promotion of Science and the 21st Century COE Program for Frontiers in Fundamental Chemistry from the Japan Ministry of Education, Culture, Sports, Science, and Technology. We are grateful for comments from T. Yoshida, J. Blundy, W.G. Ernst, and B. Harte.


   REFERENCES CITED
TOP
 ABSTRACT
 INTRODUCTION
 GEOLOGY AND PETROLOGY
 RAMAN ANALYSES
 PRESSURE-TEMPERATURE EVOLUTION
 DISCUSSION
 CONCLUSIONS
 REFERENCES CITED
 

Abers, G.A., van Keken, P.E., Kneller, E.A., Ferris, A., and Stachnik, J.C., 2006, The thermal structure of subduction zones constrained by seismic imaging: Implications for slab dehydration and wedge flow: Earth and Planetary Science Letters, v. 241 pp. 387-397 doi: 10.1016/j.epsl.2005.11.055.[CrossRef][ISI][GeoRef]

Andrews, D.J., and Sleep, N.H., 1974, Numerical modelling of tectonic flow behind island arcs: Geophysical Journal of the Royal Astronomical Society, v. 38 pp. 237-251.[ISI][GeoRef]

Arai, S., Hirai, H., and Abe, N., 2005, Geological aspects of peridotite and related xenoliths in volcanic rocks: An example from the Japan arcs: Japanese Magazine of Mineralogical and Petrological Sciences, v. 34 pp. 133-142 doi: 10.2465/gkk.34.133.[CrossRef]

Davies, G.R., Nixon, P.H., Pearson, D.G., and Obata, M., 1993, Tectonic implications of graphitized diamonds from the Ronda peridotite massif, southern Spain: Geology, v. 21 pp. 471-474 doi: 10.1130/0091-7613(1993)021<0471:TIOGDF>2.3.CO;2.[Abstract/Free Full Text][CrossRef][ISI][GeoRef]

Elliot, T., 2003, Tracers of the Slab: in Eiler, J.M., ed., Inside the Subduction Factory: American Geophysical Union Geophysical Monograph 138, pp. 23-45.

Engebretson, D.C., Cox, A., and Gordon, G., 1985, Relative Plate Motions between Oceanic and Continental Plates in the Pacific Basin: Geological Society of America Special Paper 206p. 159 p.

Forsythe, R.D., Nelson, E.P., Carr, M.J., Kaeding, M.E., Herve, M., Mpodozis, C., Soffia, J.M., and Harambour, S., 1986, Pliocene near-trench magmatism in southern Chile: A possible manifestation of ridge collision: Geology, v. 14 pp. 23-27.[Abstract][CrossRef][ISI][GeoRef]

Furukawa, Y., 1993, Magmatic processes under arcs and formation of the volcanic front: Journal of Geophysical Research, v. 98 pp. 8309-8319.[GeoRef]

Gerya, T., and Stöckhert, B., 2006, Two dimensional numerical modeling of tectonic and metamorphic histories at active continental margins: International Journal of Earth Sciences, v. 95 pp. 250-274 doi: 10.1007/s00531-005-0035-9.[CrossRef][ISI]

Goto, A., and Arai, S., 1987, Petrology of peridotite xenoliths in lamprophyre from Shingu, southwestern Japan: Implications for origin of Fe-rich mantle peridotites: Mineralogy and Petrology, v. 37 pp. 137-155 doi: 10.1007/BF01164188.[CrossRef][ISI][GeoRef]

Iwamori, H., 2000, Thermal effects of ridge subduction and its implications for the origin of granitic batholith and paired metamorphic belts: Earth and Planetary Science Letters, v. 181 pp. 131-144 doi: 10.1016/S0012-821X(00)00182-5.[CrossRef][ISI][GeoRef]

Jolivet, L., Tamaki, K., and Fournier, M., 1994, Japan Sea, opening, history and mechanism, a synthesis: Journal of Geophysical Research, v. 99 pp. 22237-22259 doi: 10.1029/93JB03463.[CrossRef]

Kagi, H., Sato, S., Akagi, T., and Kanda, H., 2007, Generation history of carbonado inferred from photoluminescence spectra, cathodoluminescence image and carbon isotopic composition: The American Mineralogist, v. 92 pp. 217-224 doi: 10.2138/am.2007.1957.[CrossRef]

Kennedy, C.S., and Kennedy, G.C., 1976, The equilibrium boundary between graphite and diamond: Journal of Geophysical Research, v. 81 pp. 2467-2470.[GeoRef]

Kimura, J.-I., Kunikoyo, T., Osaka, I., Nagao, T., Yamauchi, S., Kakubuchi, S., Okada, S., Fujibashi, N., Okada, R., Murakami, H., Kusano, T., Umeda, K., Hayashi, S., Ishimaru, T., Ninomiya, A., and Tanase, A., 2003, Late Cenozoic volcanic activity in the Chugoku area, southwest Japan arc during back-arc basin opening and reinitiation of subduction: The Island Arc, v. 12 pp. 22-45 doi: 10.1046/j.1440-1738.2003.00377.x.[CrossRef][GeoRef]

Kneller, E.A., van Keken, P.E., Karato, S., and Park, J., 2005, B-type olivine fabric in the mantle wedge: Insights from high-resolution non-Newtonian subduction models: Earth and Planetary Science Letters, v. 237 pp. 781-797 doi: 10.1016/j.epsl.2005.06.049.[CrossRef][ISI][GeoRef]

Luth, R.W., 1995, Experimental determination of the reaction dolomite + 2 coesite = diopside + 2 CO2 to 6 GPa: Contributions to Mineralogy and Petrology, v. 122 pp. 152-158 doi: 10.1007/s004100050118.[CrossRef][ISI][GeoRef]

Luth, R.W., 2001, Experimental determination of the reaction aragonite + magnesite = dolomite at 5 to 9 GPa: Contributions to Mineralogy and Petrology, v. 141 pp. 222-232.[ISI][GeoRef]

Maruyama, S., Isozaki, Y., Kimura, G., and Terabayashi, M., 1997, Paleogeographic maps of the Japanese Islands: Plate tectonic synthesis from 750 Ma to present: The Island Arc, v. 6 pp. 121-142 doi: 10.1111/j.1440-1738.1997.tb00043.x.[CrossRef]

Nakamura, E., Campbell, I.H., McCulloch, M.T., and Sun, S.-S., 1989, Chemical geodynamics in a back-arc region around the Sea of Japan: Implications for the genesis of alkaline basalts in Japan, Korea, and China: Journal of Geophysical Research, v. 94 pp. 4634-4654.[GeoRef]

Parkinson, I.J., and Arculus, R.J., 1999, The redox state of subduction zones: Insights from arc-peridotites: Chemical Geology, v. 160 pp. 409-423 doi: 10.1016/S0009-2541(99)00110-2.[CrossRef][ISI][GeoRef]

Peacock, S.M., 1996, Thermal and petrologic structure of subduction zones: in Bebout, G.E., et al., eds., Subduction: Top to Bottom: American Geophysical Union Geophysical Monograph 96, pp. 119-133.

Presnall, D.C., Gudfinnsson, G.H., and Walter, M.J., 2002, Generation of mid-ocean ridge basalts at pressures from 1 to 7 GPa: Geochimica et Cosmochimica Acta, v. 66 pp. 2073-2090 doi: 10.1016/S0016-7037(02)00890-6.[CrossRef][ISI][GeoRef]

Sdrolias, M., Roest, W.R., and Müller, R.D., 2004, An expression of Philippine Sea plate rotation: The Parece Vela and Shikoku Basins: Tectonophysics, v. 394 pp. 69-86 doi: 10.1016/j.tecto.2004.07.061.[CrossRef][ISI][GeoRef]

Shiomi, K., Sato, H., Obara, K., and Ohtake, M., 2004, Configuration of subducting Philippine Sea plate beneath southwest Japan revealed from receiver function analysis based on the multivariate autoregressive model: Journal of Geophysical Research, v. 109p. B04308 doi: 10.1029/2003JB002774.[CrossRef]

Takamura, H., 1973, Petrological and petrochemical studies of the Cenozoic basaltic rocks in the Chugoku Province: Geological Reports of Hiroshima University, v. 18 pp. 1-167.

Underwood, M.B., Laughland, M.M., Byrne, T., Hibbard, J.B., and DiTullio, L., 1992, Thermal evolution of the Tertiary Shimanto belt, Muroto Peninsula, Shikoku, Japan: The Island Arc, v. 1 pp. 116-132 doi: 10.1111/j.1440-1738.1992.tb00064.x.[CrossRef]

Uto, K., Hirai, H., Goto, K., and Arai, S., 1987, K-Ar ages of carbonate- and mantle nodule-bearing lamprophyre dikes from Shingu, central Shikoku, southwest Japan: Geochemical Journal, v. 21 pp. 283-290.[ISI][GeoRef]

Wood, B.J., Bryndzia, L.T., and Johnson, K.E., 1990, Mantle oxidation state and its relationship to tectonic environment and fluid speciation: Science, v. 248 pp. 337-345 doi: 10.1126/science.248.4953.337.[Abstract/Free Full Text][CrossRef][ISI][Medline][GeoRef]

Yamaji, A., and Yoshida, T., 1998, Multiple tectonic events in the Miocene Japan arc: The Heike microplate hypothesis: Journal of Mineralogy, Petrology, and Economic Geology, v. 93 pp. 389-408 doi: 10.2465/ganko.93.389.[CrossRef]

Received for publication 9 August 2007

Revised manuscript received 14 November 2007

Manuscript accepted 15 November 2007





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