TY - JOUR
T1 - Transition zone origin of potassic basalts from Wudalianchi volcano, northeast China
AU - Kuritani, Takeshi
AU - Kimura, Jun Ichi
AU - Ohtani, Eiji
AU - Miyamoto, Hideaki
AU - Furuyama, Katsuhiko
N1 - Funding Information:
We thank Dapeng Zhao and Shun-ichiro Karato for useful discussion. We are grateful to Yoshinori Ito for technical assistance of EPMA analysis. Editorial handling by Andrew Kerr and constructive reviews and comments by Asish Basu and one anonymous reviewer are greatly appreciated. This work was supported by the Ministry of Education, Culture, Sports, Science, and Technology of the Japanese Government (Grant-in-Aid for Young Scientists B) for T.K and by the program ‘Global Center of Excellence’ of Tohoku University .
PY - 2013/1
Y1 - 2013/1
N2 - The origin of historic potassic basalts (from the 1719 to 1721AD eruption) from the Wudalianchi volcanic field, northeast China, is investigated. The samples examined in this study are aphyric, and contain ~5vol.% olivine microphenocrysts. Geochemical analyses of the samples, along with published data for material from the 1719 to 1721AD eruption, show that the basalts exhibit linear compositional trends in whole-rock variation diagrams, and are characterized by K2O enrichment (>4wt.%) and an EM1-like isotopic signature. Using thermodynamic calculations and the observed petrological features of the basalts, the temperature of the magmas shortly before eruption is estimated to have been ~1250°C, and the water content of the magma at depth is estimated to have been >~1.1wt.%. Because the estimated temperatures are significantly higher than the projected maximum temperature of the lithospheric mantle beneath the Wudalianchi volcanic field, the magmas were likely derived from the asthenospheric mantle. We suggest that both the potassic- and EM1-like natures of the basalts originated from the mantle transition zone, metasomatized by K-rich sediment fluids ~1.5Ga ago through a stagnation of an ancient slab. The linear whole-rock compositional trends of the basalts primarily reflect the geochemical heterogeneity in the mantle transition zone, with variable but coupled contributions of ~1.5Ga sediments in the ancient stagnant slab, and recent sediments and peridotites in the stagnant Pacific slab. We infer that the Wudalianchi magmatism was caused by an upwelling of a hydrous mantle plume from the mantle transition zone, which was hydrated through the stagnation of the ancient subducted slab and the recent Pacific slab.
AB - The origin of historic potassic basalts (from the 1719 to 1721AD eruption) from the Wudalianchi volcanic field, northeast China, is investigated. The samples examined in this study are aphyric, and contain ~5vol.% olivine microphenocrysts. Geochemical analyses of the samples, along with published data for material from the 1719 to 1721AD eruption, show that the basalts exhibit linear compositional trends in whole-rock variation diagrams, and are characterized by K2O enrichment (>4wt.%) and an EM1-like isotopic signature. Using thermodynamic calculations and the observed petrological features of the basalts, the temperature of the magmas shortly before eruption is estimated to have been ~1250°C, and the water content of the magma at depth is estimated to have been >~1.1wt.%. Because the estimated temperatures are significantly higher than the projected maximum temperature of the lithospheric mantle beneath the Wudalianchi volcanic field, the magmas were likely derived from the asthenospheric mantle. We suggest that both the potassic- and EM1-like natures of the basalts originated from the mantle transition zone, metasomatized by K-rich sediment fluids ~1.5Ga ago through a stagnation of an ancient slab. The linear whole-rock compositional trends of the basalts primarily reflect the geochemical heterogeneity in the mantle transition zone, with variable but coupled contributions of ~1.5Ga sediments in the ancient stagnant slab, and recent sediments and peridotites in the stagnant Pacific slab. We infer that the Wudalianchi magmatism was caused by an upwelling of a hydrous mantle plume from the mantle transition zone, which was hydrated through the stagnation of the ancient subducted slab and the recent Pacific slab.
KW - Mantle transition zone
KW - Northeast China
KW - Potassic basalt
KW - Temperature
KW - Water
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U2 - 10.1016/j.lithos.2012.10.010
DO - 10.1016/j.lithos.2012.10.010
M3 - Article
AN - SCOPUS:84869104093
VL - 156-159
SP - 1
EP - 12
JO - Lithos
JF - Lithos
SN - 0024-4937
ER -