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| Yu, Zhiteng; Singh, Satish C.; Gregory, Emma P. M.; Maia, Marcia; Wang, Zhikai; Brunelli, Daniele. |
| Oceanic transform faults, a key element of plate tectonics, represent the first-order discontinuities along mid-ocean ridges, host large earthquakes, and induce extreme thermal gradients in lithosphere. However, the thermal structure along transform faults and its effects on earthquake generation are poorly understood. Here we report the presence of a 10- to 15-kilometer-thick in-depth band of microseismicity in 10 to 34 kilometer depth range associated with a high-temperature (700° to 900°C) mantle below the brittle lithosphere along the Romanche mega transform fault in the equatorial Atlantic Ocean. The occurrence of the shallow 2016 moment magnitude 7.1 supershear rupture earthquake and these deep microearthquakes indicate that although large... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00689/80070/83089.pdf |
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| Ponce, Alexis D.; Bertotto, Gustavo W.; Zanetti, Alberto; Brunelli, Daniele; Giovanardi, Tommaso; Aragon, Eugenio; Bernardi, Mauro I.; Hemond, Christophe; Mazzucchelli, Maurizio. |
| Cenozoic basalts carrying ultramafic mantle xenoliths occur in the Matilde, Leon and Chenque hills in the Paso de Indios region, Argentina. The mantle xenoliths from the Chenque and Leon hills mainly present porphyroclastic textures, whereas the Matilde hill xenoliths have coarse-grained to porphyroclastic textures. The equilibrium temperatures are in the range of 780 to 940 degrees C, indicating a provenance from shallow sectors of the lithospheric mantle column that were subjected to a relatively low heat flux at Cenozoic Era. According to the modal compositions of xenoliths, the mantle beneath Matilde and Leon hills was affected by greater than 22% partial melting, while less depleted peridotites occur in the Chenque suite (starting from 10% partial... |
| Tipo: Text |
Palavras-chave: Mantle xenoliths; Alkaline basalts; Paso de Indios; Patagonia. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00639/75150/75503.pdf |
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| Sauter, Daniel; Cannat, Mathilde; Roumejon, Stephane; Andreani, Muriel; Birot, Dominique; Bronner, Adrien; Brunelli, Daniele; Carlut, Julie; Delacour, Adelie; Guyader, Vivien; Macleod, Christopher J.; Manatschal, Gianreto; Mendel, Veronique; Menez, Benedicte; Pasini, Valerio; Ruellan, Etienne; Searle, Roger. |
| The global mid-ocean ridge system, where tectonic plates diverge, is traditionally thought of as the largest single volcanic feature on the Earth. Yet, wide expanses of smooth sea floor in the easternmost part of the Southwest Indian Ridge in the Indian Ocean lacks the hummocky morphology that is typical for submarine volcanism. At other slow-spreading ridges, the sea floor can extend by faulting the existing lithosphere, along only one side of the ridge axis. However, the smooth sea floor in the easternmost Southwest Indian Ridge also lacks the corrugated texture created by such faulting. Instead, the sea floor is smooth on both sides of the ridge axis and is thought to be composed of altered mantle-derived rocks. Here we use side-scan sonar to image the... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00136/24771/22950.pdf |
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| Di Giuseppe, Dario; Perchiazzi, Natale; Brunelli, Daniele; Giovanardi, Tommaso; Nodari, Luca; Della Ventura, Giancarlo; Malferrari, Daniele; Maia, Marcia; Gualtieri, Alessandro F.. |
| Tremolite is one of the most common amphibole species and, in the fibrous form (i.e., characterized by crystals/particles consisting of fibres with length > 5 µm, width < 3 µm and aspect ratio > 3), one of the six asbestos minerals. Until now the attention of crystallographers has focused only on samples from continental environment. Here we report the first chemical and structural data of a tremolite asbestos found along the Mid Atlantic Ridge (MAR) at the eastern intersection of the Romanche Transform Fault (Equatorial MAR). Tremolite is associated with chlorite and lizardite and was formed through the green shale facies lower than zeolite in a predominantly fluid system. MAR tremolite asbestos shows very slight deviations from the ideal crystal... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00685/79703/82492.pdf |
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| Maia, Marcia; Sichel, Susanna; Briais, Anne; Brunelli, Daniele; Ligi, Marco; Ferreira, Nicolas; Campos, Thomas; Mougel, Berengere; Brehme, Isa; Hemond, Christophe; Motoki, Akihisa; Moura, Denise; Scalabrin, Carla; Pessanha, Ivo; Alves, Eliane; Ayres, Arthur; Oliveira, Pedro. |
| Mantle exhumation at slow-spreading ridges is favoured by extensional tectonics through low-angle detachment faults1, 2, 3, 4, and, along transforms, by transtension due to changes in ridge/transform geometry5, 6. Less common, exhumation by compressive stresses has been proposed for the large-offset transforms of the equatorial Atlantic7, 8. Here we show, using high-resolution bathymetry, seismic and gravity data, that the northern transform fault of the St Paul system has been controlled by compressive deformation since ~10 million years ago. The long-lived transpression resulted from ridge overlap due to the propagation of the northern Mid-Atlantic Ridge segment into the transform domain, which induced the migration and segmentation of the transform... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00345/45603/49042.pdf |
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