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Earth, Planets and Space
Fig. 4 | Earth, Planets and Space

Fig. 4

From: Seafloor hydrothermal alteration affecting magnetic properties of abyssal basaltic rocks: insights from back-arc lavas of the Okinawa Trough

Fig. 4

Photomicrographs of the studied altered volcanic rock samples from the Irabu knolls of the Okinawa Trough: 6K#569R4-1 and 6K#569R4-3; A thin-section image of 6K#569R4-1 under transmitted reflected plane-polarized light (PPL). Arrows in B, C, and D are approximate positions of the following photographs. B Plagioclase (Pl) glomeroporphyritic and intersertal groundmass texture in the 6K#569R4-1. Small black minerals scattered within groundmass are pyrite. Under transmitted PPL. C Mode of occurrence of pyrite grains in the 6K#569R4-1. All bright grains are pyrite grains. Under reflected PPL. D Pyrite (FeS) and chalcopyrite (cp) grains in the 6K#569R4-1. Under reflected PPL. E Thin-section image of 6K#569R4-3 under transmitted PPL. Arrows in F, G, and H are approximate positions of the following photographs. F Plagioclase (Pl) and clinopyroxene (Cpx) glomeroporphyritic and intersertal groundmass texture in the 6K#569R4-3. Plagioclase is partly altered. Under transmitted PPL. G Bright light yellowish pyrite grains form veinlet along fracture in groundmass of the 6K#569R4-3. Under reflected PPL. H Bright light yellowish pyrite grains form veinlet along fracture in plagioclase (Pl) phenocryst of the 6K#569R4-3. Under reflected PPL. I and J Titanomagnetite (mt) grains in the 6K#569R4-3. Under reflected PPL (J: oil immersion)

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