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Plume mantle source heterogeneity through time: Insights from the Duarte Complex, Hispaniola, northeastern Caribbean

Abstract : Located in the Cordillera Central of Hispaniola, the Duarte Complex offers an opportunity to study an on-land fragment of the Caribbean-Colombian oceanic plateau. Geochemical, Sr-Nd isotope, and 40 Ar-39 Ar radiometric age data combined with detailed mapping have shown that the Duarte Complex includes two lithostratigraphic units, composed of four geochemical groups of metavolcanic rocks: Group Ia, low-Ti high-Mg basalts, and group Ib, high-Ti picrites and primitive high-Mg basalts, occur interlayered in the lowermost levels of the lower unit; group II, light rare earth element (LREE)-enriched picrites, ferropicrites and high-Mg basalts, forms the main lava sequence of the lower unit; and group III, LREE-enriched Fe-Ti basalts, is present exclusively in the upper unit. Nd isotope and incompatible trace element patterns are diverse in the Duarte Complex metavolcanics and are consistent with mantle sources related to a heterogeneous plume. Mantle melt modeling suggests that an early, extensive melting (10-20%) of shallow mantle resulted in the formation of relatively depleted group I and II magmas, whereas the late, more enriched group III magmas were the product of deeper, low-degree (<3%) melting of a heterogeneous plume. Therefore plume mantle sources were more enriched and deeper through time. Foliated amphibolites of the Duarte Complex yield 40 Ar-39 Ar hornblende plateau ages of 93.9 ± 1.4 and 95.8 ± 1.9 Ma (Cenomanian, 99.6-93.5 Ma) that demonstrate an older age of the protholiths, probably Albian (>96 Ma). Hence an Early Cretaceous phase of the Caribbean-Colombian oceanic plateau construction is recorded in Hispaniola.
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Soumis le : mardi 19 avril 2022 - 16:05:08
Dernière modification le : mercredi 20 avril 2022 - 03:42:21

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Javier Escuder-Viruete, Andrés Pérez-Estaún, Fernando Contreras, Marc Joubert, Dominique Weis, et al.. Plume mantle source heterogeneity through time: Insights from the Duarte Complex, Hispaniola, northeastern Caribbean. Journal of Geophysical Research, American Geophysical Union, 2007, 112 (B4), ⟨10.1029/2006jb004323⟩. ⟨hal-03645465⟩

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