Petrogenesis of the tholeiitic basalt, calc-alkaline basaltic andesite and high magnesian andesite lava succession of the Oligo-Miocene Anamizu Formation in northeastern Noto Peninsula, central Japan.
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Accession number;02A0639374
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| Title;Petrogenesis of the tholeiitic basalt, calc-alkaline basaltic andesite and high magnesian andesite lava succession of the Oligo-Miocene Anamizu Formation in northeastern Noto Peninsula, central Japan. |
| Author;
LOPEZ J C
(Kanazawa Univ., Kanazawa, Jpn)
ISHIWATARI A
(Kanazawa Univ., Kanazawa, Jpn)
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Journal Title;J Mineral Petrol Sci
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Journal Code:G0150B
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ISSN:1345-6296
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VOL.97;NO.3;PAGE.85-113(2002)
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| Figure&Table&Reference;FIG.15, TBL.5, REF.72 |
| Pub. Country;Japan |
| Language;English |
| Abstract;The Oligo-Miocene Anamizu Formation in the Ushitsu-Matsunami area consists of a lower volcano-sedimentary member and an upper volcanic member. The upper member is essentially composed of three lava series; tholeiite (basalt and basaltic andesite), calc-alkaline (basaltic andesite) and high-magnesian andesite (bronzite andesite), in ascending order. The tholeiitic basalt is further divided into K-poor and K-rich (K-feldespar bearing) types. The tholeiitic basaltic andesite has higher FeO*/MgO (-3) than the others (1-1.5). The calc-alkaline basaltic andesite has higher Cr and Ni than tholeiitic basaltic andesite. Bronzite andesite contains higher MgO, Cr and Ni than common calc-alkaline andesite of the same SiO2 content (-60wt%), but lower than those of boninite and sanukite. All the rock series are depleted in HFSE (Nb and Ti) in comparison with N-MORB and OIB, suggesting typical subduction-related arc magmas. High Zr/Y ratios of the tholeiitic basalt resemble those of active continental margin magmas rather than island-arc magmas. The HFSE, Ni and Cr compositions indicate a progressive depletion or increasing degree of partial melting of the mantle wedge source in the order tholeiite basalt (basaltic andesite).RAR.calc-alkaline basaltic andesite.RAR.bronzite andesite. Spinel in the three series shows different trends: Cr-poor (Cr#0.49 to 0.54) in the tholeiitic basalt, fairly Cr-rich (Cr#0.61) in the calc-alkaline basaltic andesite, and Cr-rich (Cr#0.73) in the high-magnesian andesite. These trends indicate different mantle restites; lherzolite for the tholeiitic basalt and harzburgite for the calc-alkaline basaltic andesite and high-magnesian andesite, and increasing degree of depletion in the order as above. On the contrary, LILE and LREE exhibit a gradual enrichment of the source in the same order. Corresponding decrease of TiO2/K2O suggests that the enrichment has been due to addition of fluids derived from the descending slab.... (author abst.) |
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