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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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| Szitkar, Florent. |
| Detailed submarine exploration shows a diversity of hydrothermal sites in terms of geology, minerals, fluids and biology. High0resolution, near0seafloor magnetic surveys have been undertaken on various basalt0hosted or ultramafic0hosted hydrothermal sites using a vector magnetometer mounted on deep0sea submersible Nautile, remotely operated vehicle (ROV) Victor, and autonomous underwater vehicle (AUV) AsterX of Ifremer. These surveys reveal different magnetic signatures, depending the characteristics of the hydrothermal sites. (1) Basalt-hosted sites are characterized by a negative (reduced to the pole) anomaly indicating a reduced magnetization. Two processes are often considered to explain this observation: thermal demagnetization or alteration of the... |
| Tipo: Text |
Palavras-chave: Roches ultramafiques; Processus hydrothermaux; Magnétisme; Magnetism; Ultamafic Rocks; Hydrothermal Processes. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00690/80179/83259.pdf |
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| Szitkar, Florent; Dyment, Jérôme; Fouquet, Yves. |
| Near-seafloor bathymetric and magnetic data have been collected by Autonomous Underwater Vehicle (AUV) and manned submersible (DSS) over a volcanically active area southeast of Futuna Island, French Territory of Wallis-and-Futuna, in the Southwestern Pacific Ocean. Located at the edge of the Lau and North Fiji basins, at the convergence of the Pacific and Australian plates, this area is characterized by intense volcanic and tectonic activity. Direct observation by submersible reveals that the seafloor is covered by recent lava flows, volcanoes and large, active or inactive calderas filled by smooth lava flows and eventually hosting hydrothermal sites. We investigate the volcanic chronology by combining a Bayesian inversion of the AUV-gridded magnetic data... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00651/76273/77225.pdf |
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| Szitkar, Florent; Dyment, Jerome; Fouquet, Yves; Choi, Yujin; Honsho, Chie. |
| The analysis of high-resolution vector magnetic data acquired by deep-sea submersibles (DSSs) requires the development of specific approaches adapted to their uneven tracks. We present a method that takes advantage of (1) the varying altitude of the DSS above the seafloor and (2) high-resolution multibeam bathymetric data acquired separately, at higher altitude, by an Autonomous Underwater Vehicle, to estimate the absolute magnetization intensity and the magnetic polarity of the shallow subseafloor along the DSS path. We apply this method to data collected by DSS Nautile on a small active basalt-hosted hydrothermal site. The site is associated with a lack of magnetization, in agreement with previous findings at the same kind of sites: the contrast between... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00252/36300/34829.pdf |
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