日時 ： ２０１０年３月５日（金）※16：30～
場所 ： 愛媛大学総合研究棟Ⅰ 4F 共通会議室（理学部構内）
要 旨
Abstract: Peridotite xenoliths from the Cameroon volcanic line (CVL) contain regional variations of petrography, mineral chemistry and equilibrium temperature. The xenoliths are mainly composed of spinel lherzolite, spinel harzburgite, dunite and a small amount of wehrlite and websterite. Chemical variation of lherzolite and harzburgite are explained by a process of partial melting of pyrolitic lherzolite and subsequent melt extraction in shallow mantle at a depth of 30-80 km. The Bioko, which is located near the center of the CVL, is distinctive from other regions by the higher degree of partial melting of residual peridotites. The estimated degree of partial melting in Bioko was up to 30%, although in other areas it is less than 25%. Bioko is also characterized by the amount of cumulus dunite and wehrlite. These observations indicate that extensive igneous activity occurred at the uppermost mantle under the Bioko area, and we conclude that the regional chemical variations of the CVL mantle were formed by the emplacement of a deep hot plume about 120 Ma, which caused the opening of the Atlantic Ocean. Based on this petrological result, I will discuss the potential temperature of mantle plume in the Earth’s mantle, and then predict the feature of Central Africa tectonics.
問い合わせ先：土屋 卓久 TEL （089）927-8198
E-mail takut@sci.ehime-u.ac.jp
