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| Revillon, Sidonie; Teagle, Damon A. H.; Boulvais, Philippe; Shafer, John; Neal, Clive R.. |
| Hole 1205A was drilled on Nintoku Seamount, which lies in the midportion of the Emperor Seamount Chain. This seamount was emergent similar to 56 Myr ago but was submerged by 54 Ma, so the lavas have endured weathering in both subaerial and submarine environments. We have studied the petrology, mineralogy, and geochemistry of intercalated altered basalts, breccias, and soil samples recovered at Hole 1205A to quantify the chemical exchanges between the seamount and seawater and/ or meteoric fluids. The secondary mineralogy is relatively uniform throughout the section and comprises smectite, Feoxyhydroxides, iddingsite, and Ca-carbonates. Soils are composed of variably altered basaltic clasts in a matrix of kaolinite, smectite, and vermiculite with minor... |
| Tipo: Text |
Palavras-chave: Geochemistry : major and trace element geochemistry; Geochemistry : alteration and weathering processes; Geochemistry : geochemical cycles; Oceanic island; Isotope geochemistry; Chemical fluxes; Alteration; Hole 1205A; Ocean Drilling Program. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2435.pdf |
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| Szitkar, Florent; Dyment, Jerome; Choi, Yujin; Fouquet, Yves. |
| High-resolution magnetic surveys acquired near the seafloor show that active basalt-hosted hydrothermal sites are associated with zones of lower magnetization. This observation may reflect the thermal demagnetization of a hot hydrothermal zone, the alteration of basalt affected by hydrothermal circulation, and/or the presence of thick, nonmagnetic hydrothermal deposits. In order to discriminate among these inferences, we acquired vector magnetic data 50 m above inactive hydrothermal site Krasnov using the Remotely Operated Vehicle (ROV) Victor. This deep hydrothermal site, located 7 km east of the Mid-Atlantic Ridge (MAR) axis at 16°38′N, is dissected by major normal faults and shows no evidence of recent hydrothermal activity. It is therefore a perfect... |
| Tipo: Text |
Palavras-chave: Magnetic anomalies; Hydrothermalism; Alteration; Modeling. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00188/29915/28375.pdf |
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