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| Gernigon, Laurent; Lucazeau, Francis; Brigaud, Frederic; Ringenbach, Jean-claude; Planke, Sverre; Le Gall, Bernard. |
| High P-wave velocities (7.1-7.8 km/s) lower crustal bodies (LCBs) imaged along volcanic margins are commonly interpreted as plume and break-up-related thick mafic underplating. This interpretation is partly challenged in this paper based on new seismic observations and modelling of the outer Voring Basin (Norway). An exceptional strong amplitude reflection, the T Reflection, is particularly well defined below the North Gjallar Ridge (NGR) between 7 and 8 s TWT. The T Reflection is located near the volcanic lava flows emplaced during the NE Atlantic breakup (similar to 55-54 Ma ago) and coincides with the top of the LCB, forming a mid-crustal dome. Based on structural and temporal relationships, we show that the dome clearly influences the structural... |
| Tipo: Text |
Palavras-chave: Mantle plume; Norwegian margin; Underplating; Breakup; Modelling; Rifting; Volcanic margins. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1042.pdf |
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| Borisova, Anastassia Y.; Bohrson, Wendy A.; Gregoire, Michel. |
| Chemical Geodynamics relies on a paradigm that the isotopic composition of ocean island basalt (OIB) represents equilibrium with its primary mantle sources. However, the discovery of huge isotopic heterogeneity within olivine-hosted melt inclusions in primitive basalts from Kerguelen, Iceland, Hawaii and South Pacific Polynesia islands implies open-system behavior of OIBs, where during magma residence and transport, basaltic melts are contaminated by surrounding lithosphere. To constrain the processes of crustal assimilation by OIBs, we employed the Magma Chamber Simulator (MCS), an energy-constrained thermodynamic model of recharge, assimilation and fractional crystallization. For a case study of the 21–19 Ma basaltic series, the most primitive series... |
| Tipo: Text |
Palavras-chave: Ocean island basalt; Kerguelen; Mantle plume; Ocean metagabbro xenoliths; Crustal assimilation and fractional crystallization; Magma Chamber Simulator. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00393/50409/51128.pdf |
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| Bonneville, Alain; Dosso, Laure; Hildenbrand, Anthony. |
| We are presenting a new set of K/Ar ages and geochemical analyses obtained on deep-sea samples dredged in 1999 on several seamounts of the Cook-Austral volcanic chains in the Pacific Ocean. The new geochemical results, together with published data on island samples, allow us to reveal a time evolution of the mantle source composition as well as an increase in geochemical variability of the superplume responsible for the regional South Pacific Superswell. Three identified volcanic stages of 58-40, 33-20 and 20-0 Ma are identified with signatures of mantle reservoir composition varying from close to C to N-MORB-types and C/HFMU-type, respectively. Using a geodynamic reconstruction for the most recent volcanic period, from 20 Ma to present, three hotspot... |
| Tipo: Text |
Palavras-chave: Hotspot; Cook Austral; Seamount ages; Geochemical sources; South Pacific Superswell; Mantle plume. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1559.pdf |
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| Weis, D; Frey, Fa; Schlich, R; Schaming, M; Montigny, R; Damasceno, D; Mattielli, N; Nicolaysen, Ke; Scoates, Js. |
| The gravity and bathymetric highs on the Kerguelen Plateau in the southern Indian Ocean between the Kerguelen Archipelago and Heard Island are seamounts formed of Miocene alkalic basalts similar to those found on the islands. Dredging during the Kerimis survey cruise recovered >1 ton of mostly basaltic rocks. One of the dredges (D6) yielded a large volume of in situ alkalic picritic pillow basalts, the first picritic lavas recovered that are related to the Kerguelen plume. K-Ar and Ar-40-Ar-39 ages are between 18 and 21 Ma for all but one sample, and these ages are only slightly younger than the main phase of volcanism on the archipelago. The dredged lavas form three distinct groups based on chemical and isotopic compositions. Incompatible element... |
| Tipo: Text |
Palavras-chave: Kerguelen; Trace elements; Isotopes; Mantle plume; Hot spot track; Picrites; Geochemistry; 1025 Geochemistry : Composition of the mantle; 1040 Geochemistry : Isotopic composition/chemistry; 1065 Geochemistry : Trace elements (3670). |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33407/31856.pdf |
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