Picrite basalts from the Pliocene Uegusukudake Formation in Kume-jima, Ryukyu Islands.
Picrite basalts from the Pliocene Uegusukudake Formation in Kume-jima, Ryukyu Islands.
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琉球群岛久米岛上新世上城岳组的苦味玄武岩。
DOI：
10.5575/geosoc.105.810
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
K. Shiraki
中科院分区：
文献类型：
--
作者：
J. Ito;K. Shiraki
含MgO最高达16重量%的苦橄玄武岩发现于久米岛北岸上新世Uegusukudake组的最低部分，在岛西北部附近是一个活动的弧后盆地--冲绳海槽。苦橄玄武岩中高的橄榄石Fo（92.2）和尖晶石Cr2 O3（56.5%）表明存在MgO>13%，Cr2 O3>0.15%的岩浆。久米岛苦橄玄武岩是一种具有较高SiO2和较低不相容元素丰度的拉斑玄武岩弧苦橄岩，可能是伴随着冲绳海槽的开启而形成的。
Picrite basalts containing MgO up to 16 wt.% were found in the lowest part of the Pliocene Uegusukudake Formation on the north coast of Kumejima island ; in the close proximity northwest of the island lies an active back-arc basin, Okinawa Trough. The high Fo (92.2) of olivine and Cr2O3 (56.5%) of spinel in the picrite basalts indicate the existence of a magma with >13% MgO and >0.15% Cr2O3. The Kumejima picrite basalts are tholeiitic arc picrites having relatively high SiO2 and low incompatible element abundances.They may have formed accompanying the opening of the Okinawa Trough.