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Materi/Makalah Forum Hasil Penelitian Hidrothermal Gunung Api Bawah Laut

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In the meantime we have started to study samples which were taken to our institute after the Bandamin cruise. The available samples originate from different dredge hauls of the surroundings of the Abangkomba Seamount, mostly from water depths between 400 and 800 m. Since we have carried out a very detailed bathymetric mapping of the area between the Komba Volcano and the Island of Pantar, we came to the conclusion that the two seamounts (Abangkomba and Ibukomba) and the Komba Volcano form a ridge structure. This ridge structure is caused mainly by extensional deformation which can be explained by a break-up of the Flores Sea crust due to the special tectonic situation of the volcanic island arc regime between Flores and Wetar Islands. This suggested extension is also responsible for the upwelling of the more alkaline magmas. The rock samples represent varying grades of alteration. The main minerals of the less altered samples are feldspar (plagioclase, less often sanidine), hornblende, and biotite. The primary volcanic rock is a biotite-bearing trachyandesite, the sum of potassiumand sodium-oxide varies between 7 and 9h in the less altered samples. The more altered samples show decreasing concentrations of Na,O and less pronounced of K5O, associated also with a weak increase in SiO,. The SiO, concentration of the most altered rock samples increases up to 65545. Using a defined alteration index ((K2O # MgO) x 100 / sum of CaO # MgO # Na,O #K,O), components like Na,O, K-O, CaO, and MgO decrease with increasing alteration.

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Ketersediaan

Informasi Detail

Judul Seri

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No. Panggil

549 MAT

Penerbit

jakarta : Balitbang.,

Deskripsi Fisik

190hlm; Ilus Tak Berwarna; 29 cm

Bahasa

ISBN/ISSN

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Klasifikasi

549

Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

Hidrothermal

Info Detail Spesifik

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Pernyataan Tanggungjawab

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Versi lain/terkait

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