北西フィリピン海域,とくに大東海嶺域と沖大東海嶺域の火山岩類について : GDP-15,21航海の岩石化学的成果

概要

論文の詳細を見る
A few samples of the andesitic and basaltic rocks were collected from the Daito Ridge and Okidaito Ridge regions, Northwestern Philippine Sea, during the GDP-15 Cruise in 1975 and GDP-21 Cruise in 1976, as shown in Fig. 1. The data on continuous seismic profiling obtained and Nummulites dredged from these regions indicate that the volcanic rocks (15-2 and 15-3) in the Daito Ridge region intruded after the deposition of the Eocene Nummlities-bearing sediments, whereas the volcanic rocks (21-5) in the Okidaito Ridge region seem to be covered by the said sediments. As the results of a examination on their major chemical elements of these rocks, it is clarified that the striking difference as shown in Fig. 4 is distinguished between them. The volcanics of the Daito Ridge region are characterized by higher contents of K_2O + Na_2O than those of the Okidaito Ridge region and similar to the trachyandesite distributed on the Iwo Island. The volcanics of the Okidaito Ridge region are similar to those of the Island Arc Tholeiite type typical in the Izu-Mariana Island arc expect for higher content of TiO_2(>4%) in the former as compared with the latter (Fig. 3). The secondary alteration of the volcanics by the interaction with sea-water will not be enough to produce such a high content of TiO_2 in them. So we suggest the possibility that the chemical composition of the volcanic rocks on these regions will be primary and that these differences in the petrochemical character of the volcanic rocks in each region may reflect the fundamental characters of primary magma before and after Eocene.
地学団体研究会の論文
1978-09-25

北西フィリピン海域,とくに大東海嶺域と沖大東海嶺域の火山岩類について : GDP-15,21航海の岩石化学的成果

スポンサーリンク

概要

著者

関連論文

スポンサーリンク