Geochemistry of igneous rocks of Shimane Peninsula, formed within a Miocene back-arc rifting zone at the Japan Sea margin.

Miyake, Yasuyuki

doi:10.2343/geochemj.28.451

Cited by 21 publications

(19 citation statements)

References 36 publications

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“…Nd isotopic ratios of the Lee River Group basalts at 280 Ma range from 0.51266 to 0.51270 (eNd = +7.5 to +8.3), suggesting that the rocks are derived from a depleted mantle source. In the Red Hills basalts this effect is not recognised, but the concentrations are still within the range of island arc basalts (Miyake 1994;Thirlwall et al 1994). In the Red Hills basalts, some high field strength elements, such as Zr and Ti, and REE have low concentration.…”

Section: Tectonic Settingmentioning

confidence: 99%

Geochemistry of dike rocks in Dun Mountain Ophiolite, Nelson, New Zealand

Sano

Tazaki

Koide

et al. 1997

New Zealand Journal of Geology and Geophysics

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Basaltic dikes of the Lee River Group (Permian) at Roding River and in the Red Hills ultramafic body, both parts of the Dun Mountain Ophiolite, were analysed for major and trace elements. The dikes in the Lee River Group change into massive and pillowed lava towards the uppermost part of the sequence. The dikes in the Red Hills occur parallel to the layering of host ultramafic rocks. The Red Hills ultramafic body corresponds to the mantle-crust transition zone. The age of Red Hills dikes has been determined at c. 280 Ma. Hence, the Lee River Group and Red Hills dike complexes are about the same age. There are G96015Received 29 April 1996; accepted 24 September 1996 contrasting differences, however, between major and trace element compositions in those two dike rock groups. Lee River Group basalts show an increase in FeO*/MgO with increase in SiO 2 ; high field strength elements and REE concentrations are higher in the Lee River Group than those in the Red Hills basalts; and eNd values are +7.5 to +8.3, suggesting the source to be depleted mantle. On the other hand, Red Hills basalts do not show an increase in FeO*/ MgO with increase in SiO 2 , and are relatively enriched in large ion lithophile elements such as Ba and Sr, depleted in high field strength elements and REE, and eNd values (+6.2 and +7

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Section: Tectonic Settingmentioning

confidence: 99%

Geochemistry of dike rocks in Dun Mountain Ophiolite, Nelson, New Zealand

Sano

Tazaki

Koide

et al. 1997

New Zealand Journal of Geology and Geophysics

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“…;Miyake, 1994) (ca. 16-15 Ma) have relatively high LILE abundances with relatively low REEs and HFSEs, and the oldest sample is very simi-lar to E-MORB except for highly incompatible LILEs and Sr (Fig.…”

Section: Stage IImentioning

confidence: 99%

“…5). These basalts have major element compositions that are intermediate between LAT and calc-alkalic suites (Miyake, 1994;Morris et al, 1990;Morris et al, 1999;Uto et al, 1994). In this context, Matsue LAT basalts are transitional between oceanic tholeiite and arc basalt and are similar to back-arc basin tholeiites (Taylor and Martinez, 2003).…”

Section: Stage IImentioning

confidence: 99%

“…Basalts with arclike trace element signatures erupted on the Yamato Bank between 26 and 22 Ma, whereas MORB-like tholeiitic basalts dominated in the Yamato Basin before and after opening (22-13 Ma) (Pouclet et al, 1995). The transitional nature of LAT basalt in SW Japan may refl ect contributions from the continental lithosphere, which was metasomatized by subduction at the Asian continental margin (Miyake, 1994;Morris et al, 1990;Morris et al, 1999;Uto et al, 1994).…”

Section: Stage IImentioning

confidence: 99%

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Reinitiation of subduction and magmatic responses in SW Japan during Neogene time

Kimura

Stern

Yoshida

2005

Geol Soc America Bull

221

266

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Southwestern Japan during Paleogene time was affected by subduction of the Kula and Pacifi c plates beneath the eastern margin of Eurasia, followed by a brief episode of transform faulting to allow the Shikoku Basin to open at 27-15 Ma. Subsequent opening of the Japan Sea back-arc basin in middle Miocene time broke Japan away from Eurasia, and SW Japan rotated clockwise ~45º as it drifted south (17-15 Ma). Southward drift required subduction of the Philippine Sea plate beneath SW Japan, leading to the formation of a magmatic arc. Subduction of the hot Shikoku Basin lithosphere and spreading ridge resulted in distinctive volcanism in the SW Japan forearc between 17 and 12 Ma. This volcanism included midoceanic-ridge basalt (MORB)-like intrusions and oceanic-island basalt (OIB)-type alkali basalts, felsic plutons in the accretionary prism, and high-magnesium andesites along the Setouchi forearc basin. Mafi c magmas in the outermost forearc originated from the subducted Shikoku Basin spreading ridge, whereas Setouchi high-magnesium andesites (HMA) may have resulted from the interaction of melts of the subducted Philippine Sea plate with the overlying mantle. Felsic magmas in the forearc resulted from melting of Shimanto Belt sediments caused by intrusion of HMA magmas. Persistent rear-arc volcanism was caused by upwelling asthenosphere associated with opening of the Sea of Japan. Rear-arc volcanism began ca. 25 Ma as rift-fi ll low-alkali tholeiite volca-nism and was replaced gradually after 12 Ma by alkali basalt volcanism. Upwelling-related alkali volcanism continues up to the present, whereas forearc volcanism ceased at 12 Ma.The volcanic arc narrowed with time as the Philippine Sea slab descended and slowly cooled. Adakitic dacites erupted after 1.7 Ma above the 100-km-depth contour of the subducted Philippine Sea plate, suggesting that melting resulted from interaction of the slab with upwelling asthenosphere. Interactions between upwelled rear-arc asthenosphere and subduction of the hot Philippine Sea slab appear to have been the main controls of magmatism for the Neogene SW Japan arc.

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“…Olivine-bearing basalts show a limited range in Zr, P,05, Ba, and Sr with decreasing (Miyake 1994). Samples with complete R E E by ICP-MS at CCWA; also includes ICP-MS data for Hf, Th, U, Y. Sm and Nd in 17 and 18 from Morris and Kagami (1989).…”

Section: Major and Trace Element Chemistrymentioning

confidence: 97%

The Matsue Formation: Evidence for gross mantle heterogeneity beneath Southwest Japan at 11 Ma

Morris¹,

Itaya²

1997

Island Arc

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Middle Miocene basalts and basaltic andesites of the Matsue Formation outcrop within a 5 km radius of Matsue city in eastern Shimane Prefecture. Despite their limited outcrop and age (11.0 2 1.5 Ma), they show a wide range in s7Sr-s6Sr(0.70370-0.70593), 143Nd-144Nd(0.512904-0.512471) and large ion lithophile element (LILE) contents, but a relatively narrow range for some high field strength elements (HFSE) such as Nb and Ti. These basalts and andesites can be divided into three groups based on petrography, major element, trace element and isotope chemistry. Although onF group has uncfergone some fractional crystallization, isotope chemistry precludes linkage of the groups by a closed-system process. Crustal contamination can explain isotope chemistry, but is not consistent with trace element variations. The most satisfactory model is eruption of two compositionally distinct magmas, with limited magma mixing and fractional crystallization. Published experimental work shows that one end-member resulted from shallow melting of upwelling mantle at -25 km. The simultaneous eruption of the other end member magma in the same area points towards a heterogeneous mantle. The isotopic composition of Matsue Formation basalts and andesites covers the entire range of Late Miocene mafic volcanic rocks of southwest Japan. Such gross heterogeneity developed on a local scale has implications for models that deal with regional chemical variations of mafic volcanic rocks in southwest Honshu.

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Geochemistry of igneous rocks of Shimane Peninsula, formed within a Miocene back-arc rifting zone at the Japan Sea margin.

Cited by 21 publications

References 36 publications

Geochemistry of dike rocks in Dun Mountain Ophiolite, Nelson, New Zealand

Geochemistry of dike rocks in Dun Mountain Ophiolite, Nelson, New Zealand

Reinitiation of subduction and magmatic responses in SW Japan during Neogene time

The Matsue Formation: Evidence for gross mantle heterogeneity beneath Southwest Japan at 11 Ma

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