Noémie Bosc, Delphine Bosch, Mélanie Noury, Olivier Bruguier, Lény Montheil, Douwe J. J. van Hinsbergen, Jean-Jacques Cornée, Jonathan Outin, Mélody Philippon
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引用次数: 0
Abstract
The British Virgin Islands (BVI) archipelago, located between the Greater Antilles and the Lesser Antilles, is a key location to study the geodynamic evolution of the Caribbean plate. Geochemistry of the studied samples reveals typical volcanic arc signatures, including a calc-alkaline affinity, strong negative HFSE anomalies, and LILE enrichment. The ɛHf values are homogeneous, indicative of a MORB-type mantle. Magmas were sourced from a homogeneous mantle wedge with less than 2% slab-derived sediment inputs, dominated by aqueous fluids. A concomitant melt component has been detected in the Peter and Norman Islands. U-Pb dating emphasizes an active magmatic period spanning over ca. 13 Myr (43–30 Ma), with a NE/SW decreasing age gradient. Thermobarometry data display a SW increasing emplacement depth from ∼6 to 13 km. Compared to the Greater and Lesser Antilles, this archipelago shows strong similarities with the extinct northern Lesser Antilles arc in terms of source and age. A geodynamical evolution model is proposed in which this archipelago represents a transition between the Greater and the Lesser Antilles arcs. The Oligocene cessation of magmatism (ca. 30 Ma) may coincide with a regionally documented lull in arc magmatic activity during which the Bahamas bank collided to the north. Paleomagnetic evidence of forearc sliver motion along the northeastern boundary of the Caribbean indicates a northward translation of the archipelago from a position above the Lesser Antilles subduction zone to its modern location along the highly oblique, strike-slip-dominated plate boundary, thus preventing the re-establishment of arc magmatism in the eastern Caribbean.
期刊介绍:
Geochemistry, Geophysics, Geosystems (G3) publishes research papers on Earth and planetary processes with a focus on understanding the Earth as a system. Observational, experimental, and theoretical investigations of the solid Earth, hydrosphere, atmosphere, biosphere, and solar system at all spatial and temporal scales are welcome. Articles should be of broad interest, and interdisciplinary approaches are encouraged.
Areas of interest for this peer-reviewed journal include, but are not limited to:
The physics and chemistry of the Earth, including its structure, composition, physical properties, dynamics, and evolution
Principles and applications of geochemical proxies to studies of Earth history
The physical properties, composition, and temporal evolution of the Earth''s major reservoirs and the coupling between them
The dynamics of geochemical and biogeochemical cycles at all spatial and temporal scales
Physical and cosmochemical constraints on the composition, origin, and evolution of the Earth and other terrestrial planets
The chemistry and physics of solar system materials that are relevant to the formation, evolution, and current state of the Earth and the planets
Advances in modeling, observation, and experimentation that are of widespread interest in the geosciences.