| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1987: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1986: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1985: ¥600,000 (Direct Cost: ¥600,000)
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| Research Abstract |
1. Neogene formation which is distributed in the north Kinki district is divided into two groups, the Miocene Hokutan and the Pliocene Teragi Groups. (1) The Hokutan Group is further divided into the Takayanagi, the Yoka, the Toyooka, the Muraoka.Amino and the Tango Formations in ascending order. (2) The Teragi Group is divided into the Basal Conglomerate, the Utaosa Rhyolite, the Yudani Conglomerate, the Haruki Mud and the Terada Volcanics.
2 (1) The lower part of the Yoka Formation is mainly composed of basic pyroclastic rocks and the upper part is mainly composed of basaltic lavas, which are olivine augite basalts in the Hamasaka and the Yoka districts, and olivine basalts in the Tango district. (2) The rhyolitic volcanic rocks are intercalated in the Toyooka Formation (Hide rhyolitea). The basaltic (Sugano Andesites) and rhyolitic lavas (Honzaka Rhyolites) are interbedded in the Amino formation. (3) The volcanic rocks in the Tango Formation (Nakahama Two pyroxene andesites) are charcterized by dacite. (4) The Teragi Group is characterized by the rhyolitic welded tuff in the lower part (Utaosa Rhyolite) and basaltic-andestic volcanic rocks in the upper part (Terada Volcanics).
3. (1) The volcanic rocks from the Yoka Formation range from the tholeiitic to the alkaline basalts. (2) The basalts from the Amino and the Teragi Formations are tholeiitic. (3) The andesites and dacites from the Amino and the Tango Formations are tholeiitic, and those from the Teragi Group are calc -alkaline. (4) The volcanism of the alkali basalits begun at the pleistocene age in the north Kinki district (Genbudo, Oginosen, Kannabe). (5) The basalts from the Yoka Formation are characterized by the low contents of HFSEs. On the contrary, those from the Teragi Group are rich in HFSEs. The fact suggests the difference of the mantle chemistry between the Miocene and the Pliocene ages in the north Kinki district.
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