NAIR K.K.K. Geological Survey of India, Senior scientist, デカン高原研究部, 主任研究員
CHATTERJEE A.K. Geological Survey of India, Junior scientist, デカン高原研究部, 研究員
YEDEKAR D.B. Geological Survey of India, Senior scientist, デカン高原研究部, 主任研究員
DESHMUKH S.S. Geological Survey of India, Director, デカン高原研究部, 統括部長
YAMASHITA Shigeru Res. Inst. for Earth's Interior, Okayama Univ., Research Associate, 地球内部研究センター, 助手
YASUDA Atsushi Earthquake Res. Inst., Univ. of Tokyo, Research Associate, 地震研究所, 助手 (70222354)
KANEKO Takayuki Earthquake Res. Inst., Univ. of Tokyo, Research Associate, 地震研究所, 助手 (90221887)
UMINO Susumu Faculty of Science, Shizuoka Univ., Assoc.Professor, 理学部, 助教授 (30192511)
OZAWA Kazuhito Faculty of Science, Univ. of Tokyo, Assoc.Professor, 理学系研究科, 助教授 (90160853)
ARAMAKI Shigeo Faculty of Science, Hokkaido Univ., Professor, 理学部, 教授 (60012895)
HAMANO Yozo Faculty of Science, Univ. of Tokyo, Professor, 理学系研究科, 教授 (90011709)
KANEKOKA Ichiro Earthquake Res. Inst., Univ. of Tokyo, Professor, 地震研究所, 教授 (30011745)
YEDEKAR D B インド地質調査所, デカン研究部, 主任研究官
DESHMUKH S S インド地質調査所, デカン研究部, 部長
|Budget Amount *help
¥20,500,000 (Direct Cost : ¥20,500,000)
Fiscal Year 1993 : ¥9,500,000 (Direct Cost : ¥9,500,000)
Fiscal Year 1992 : ¥11,000,000 (Direct Cost : ¥11,000,000)
Field surveys at Deccan Plateau were carried out in three seasons ; January, 1993, October, 1993 and December, 1993 to January, 1994. During the first field season, east-west traverse of the region of Deccan flood basalt was carried out, and the basaltic agglutinates were recognized in the eastern portion of the plateau. This indicates that the eruption center of the flood basalt is not restricted at the western portion of the Deccan plateau. During the second field season, plateau basalt lava was found near Panna area, where no basaltic activity have not been described. This indicates that the distribution of the Deccan flood basalt should be revised to the further north and the erupted volume could be much larger than ever estimated.
During the third field season, two different trends of dikes were recognized ; E-W and N-S. They sometimes cut each other, indicating the two different fissure systems were available during the Deccan plateau volcanism.
More than 300 samples were analyzed with XRF. Most striking feature is that the magnesian basalt which contains more than 9wt % of MgO contains accumulated olivine phenocrysts and that the liquid composition should be less magnesian ; less than 7wt % of MgO. This indicates that the picrite primary magma cannot be the parental magma for the Deccan flood basalt. Also, the chemical trend within the Deccan flood basalt cannot be explained by simple fractional crystallization, but can be explained several different basaltic parental magmas with different alkali and titanium contents. Some of the primitive basaltic rocks were found to show chemical feature which resemble the partial melt of MORBs at high pressure. This may suggest that the source materials for the Deccan flood basalt may not be mantle peridotite, but MORBs which had subducted into the mantle in the much older time.