Éditeur(s) : Hamburg, Paris, Milano : The Albatross
Siècle(s) traité(s) : 20
Provenance : Université Caen Normandie. Service commun de la documentation
Permalien : http://www.manioc.org/patrimon/CAE19035
CAE19035

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Chromitite pods in the Mayarí-Cristal ophiolitic massif (eastern Cuba) were formed in the Late Cretaceous when island arc tholeiites and MORB-like back-arc basin basalts reacted with residual mantle peridotites and generated chromite-rich bodies enclosed in dunite envelopes. Platinum-group minerals (PGM) in the podiform chromitites exhibit important Os-isotope heterogeneities at the kilometric, hand sample and thin section scales. 187Os/188Os calculated at the time of chromitite crystallization (~90 Ma) ranges between 0.1185 and 0.1295 (γOs = −7.1 to +1.6, relative to enstatite chondrite), and all but one PGM have subchondritic 187Os/188Os. Grains in a single hand sample have initial 187Os/188Os that spans from 0.1185 to 0.1274, and in one thin section it varies between 0.1185 and 0.1232 in two PGM included in chromite which are only several millimeters apart. As the Os budget of a single micrometric grain derives from a mantle region that was at least several m3 in size, the variable Os isotopic composition of PGM in the Mayarí-Cristal chromitites probably reflects the heterogeneity of their mantle sources on the 10-100 m scale. Our results show that this heterogeneity was not erased by pooling and mingling of individual melt batches during chromitite crystallization but was transferred to the ore deposits on mineral scale. The distribution of the Os model ages calculated for PGM shows four main peaks, at ~100, 500, 750 and 1,000 Ma. These variable Os model ages reflect the presence of different depleted domains in the oceanic (Pacific-related) upper mantle of the Greater Antilles paleo-subduction zone. The concordance between the age of crystallization of the Mayarí-Cristal chromitites and the most recent peak of the Os model age distribution in PGM supports that Os in several grains was derived from fertile domains of the upper mantle, whose bulk Os isotopic composition is best approximated by that of enstatite chondrites; on the other hand, most PGM are crystallized by melts that tapped highly refractory mantle sources.
ISSN: 0010-7999

hal-00822742
https://hal.archives-ouvertes.fr/hal-00822742
DOI : 10.1007/s00410-010-0575-2

Éditeur(s) : New-York : American anti-slavery society
Siècle(s) traité(s) : 18
Droits : Domaine public
Provenance : Collectivité territoriale de Martinique. Bibliothèque Schoelcher
Permalien : http://www.manioc.org/patrimon/SCH13214
SCH13214

Éditeur(s) : HAL CCSD
Résumé : International audience
Dans la cadre de calcul de risques sismiques, nous nous intéressons aux processus ponctuels auto-excitatifs. Une étude comparative de deux modèles est effectuée, il s'agit des modèles ETAS (Epidemic Type Aftershock Sequence) introduit et modifié par Ogata (1988, 1998) et BASS (Branching AfterSchock Sequence) introduit par Turcotte et al. (2007).
19th Caribbean Geological Conference 2011
Le Gosier, Guadeloupe

hal-00601511
https://hal.archives-ouvertes.fr/hal-00601511

Éditeur(s) : [S.l.] : Murray
Siècle(s) traité(s) : 15
Droits : Domaine public
Provenance : Université des Antilles. Service commun de la documentation
Permalien : http://www.manioc.org/patrimon/HASH117f75b891912290c62713
HASH117f75b891912290c62713

Éditeur(s) : [S.l.] : Harper
Siècle(s) traité(s) : 19
Droits : Domaine public
Provenance : Université des Antilles. Service commun de la documentation
Permalien : http://www.manioc.org/patrimon/HASH40423832e7422746ff4d15
HASH40423832e7422746ff4d15