Geochemical characteristics of the Río Verde Complex, Central Hispaniola: Implications for the paleotectonic reconstruction of the Lower Cretaceous Caribbean island-arc Javier Escuder-Viruete a, ⁎, Andrés Pérez-Estaún b , Dominique Weis c , Richard Friedman c a Instituto Geológico y Minero de España, C. La Calera 1, Tres Cantos, 28760 Madrid, Spain b Instituto Ciencias Tierra Jaume Almera-CSIC, Lluís Solé Sabarís s/n, 08028 Barcelona, Spain c Pacific Centre for Isotopic and Geochemical Research, University of British Columbia, 6339 Stores Road Vancouver, Canada BC V6T 1Z4 abstract article info Article history: Received 20 November 2008 Accepted 12 August 2009 Available online 23 August 2009 Keywords: Island-arc Back-arc basin Mantle melting Hispaniola Caribbean plate New geochronological, trace element and Sr–Nd isotope data for metabasalts, dolerites and amphibolites from the Río Verde Complex, Central Hispaniola, are integrated with existing geochemical data for mafic volcanic rocks and metamorphic derivatives from the Los Ranchos, Amina and Maimón Formations, giving new insights into magma petrogenesis and paleotectonic reconstruction of the Lower Cretaceous Caribbean island-arc–back arc system. U–Pb and 40 Ar/ 39 Ar age data show that the Río Verde Complex protoliths were in part coeval with volcanic rocks of the Los Ranchos Formation (Upper Aptian to Lower Albian). The geochemical data establish the existence of gradients in trace element parameters (Nb/Yb, Th/Yb, Zr/Yb, Zr/ Ba, and normalized Ti, Sm, Y and Yb abundances) and Nd isotope compositions from throughout Hispaniola, which reflect differences in the degree of mantle wedge depletion and contributions from the subducting slab. The Río Verde Complex mafic rocks and some mafic sills and dykes intruding in the Loma Caribe Peridotite, have a transitional IAT to N-MORB geochemistry and a weak subduction-related signature, and are interpreted to form in a rifted arc or evolving back-arc basin setting. The Los Ranchos, Amina and Maimón Formations volcanic rocks have arc-like characteristics and represent magmatism in the volcanic front. Trace element and Nd isotope modeling reproduce observed data trends from arc to back-arc and suggest that the variations in several geochemical parameters observed in a SW direction across the Caribbean subduction system can be explained from the progressively lower subduction flux into a progressively less depleted mantle source. The low Nb contents and high (ε Nd ) i values in both arc and back- arc mafic rocks imply, however, the absence of a significant Lower Cretaceous plume enriched component. In order to explain these observations, a model of proto-Caribbean oceanic lithosphere subducting to the SW at least in the 120–110 Ma interval, is proposed to cause the observed magmatic variations in the Lower Cretaceous Caribbean island-arc–back-arc system. In this context, arc rifting and initial sea-floor spreading to form the Río Verde Complex protoliths occurred in the back-arc setting of this primitive island-arc, built on the NE edge of the Caribbean plate. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Island-arcs develop because of subduction of oceanic lithosphere beneath another oceanic plate. The aqueous fluids and/or hydrous melts released from the subducting slab and their reaction with the overlying mantle wedge provide the prime control on arc magma genesis (Hawkesworth et al., 1993; Pearce and Peate, 1995; Wood- head et al., 1998; Stern, 2002). Magma genesis processes along convergent plate boundaries mainly include: (1) adiabatic upwelling of asthenospheric mantle induced by slab penetration (Peacock and Wang, 1999; Gerya et al., 2004); (2) partial melting of the mantle wedge as a result of the addition of slab-derived fluids (Arculus and Powell, 1986; Pearce and Parkinson, 1993; Schmidt and Poli, 1998; Hochstaedter et al., 2001; Martinez and Taylor, 2002); and (3) melting of the subducted slab and addition of the resultant melts to the mantle wedge (Defant and Drummond, 1990; Yogodzinski et al., 2001; Tatsumi and Hanyu, 2003). The compositions of arc lavas can vary across and along individual arcs. This probably results from: (1) compositional differences in subducted slab rocks (Plank and Langmuir, 1993); (2) differences in the dehydration or melting conditions of slab materials (Defant and Drummond, 1990); (3) differences in degree of partial melting in the mantle wedge (Pearce and Parkinson, 1993); (4) differences in the volume of slab-derived components added to the overlying mantle wedge (Kelemen et al., 2003; Singer et al., 2007); and Lithos 114 (2010) 168–185 ⁎ Corresponding author. Instituto Geológico y Minero de España. C. La Calera 1, 28760 Tres Cantos, Madrid. Spain. Tel.: +34 917287242. E-mail address: j.escuder@igme.es (J. Escuder-Viruete). 0024-4937/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.lithos.2009.08.007 Contents lists available at ScienceDirect Lithos journal homepage: www.elsevier.com/locate/lithos