The geochemistry of young volcanism throughout western Panama and southeastern Costa Rica: an overview

Abstract

Oblique aseismic subduction below western Panama and southeastern Costa Rica has produced Recent arc-related volcanism. The aseismicity is probably related to the subduction of relatively hot oceanic lithosphere. The volcanism throughout this region over the past 2 Ma has been quite distinct, consisting of felsic magmas (andesites to rhyolites but mainly dacites) with geochemical signatures suggesting a metamorphosed basaltic source. It is believed that the subduction of young oceanic crust sets up conditions under which the slab melts rather than the overlying mantle wedge. Rocks with slab-melt geochemistries and associated with young subducted crust have been termed adakites elsewhere. The young adakite melts are sometimes associated with a few rare young high-Nb basalts, but there is no obvious genetic link between them through differentiation. High-Nb basalts may also be derived from the partial melting of the subducted oceanic crust. High-Nb basalt migmatites have been found with pegmatites of adakite compositions in the exposed subduction terrain of the Catalina Schist, California. Alternatively, the high-Nb basalts may be partial melts of phlogopite-rich mantle that has previously reacted with adakite magmas. Eruption of adakites and high-Nb basalts was preceded by a 2-3 Ma period of relative quiescence. Prior to this, there was a 7 Ma period of calc-alkaline volcanism typical of the present-day magmatism (associated with a distinct Benioff zone) found throughout the Central American arc. The abrupt transition in volcanism with time from an early calc-alkaline sequence to a later adakite-high-Nb basalt sequence may record a change in the tectonic setting of western Panama and southeastern Costa Rica over the past 12 Ma.

A Late Carboniferous–Early Permian slab window in the West Junggar of NW China: Geochronological and geochemical evidence from mafic to intermediate dikes

“…Like addressed in previous studies (Defant et al, 1992;Sajona et al, 1996;Tatsumi and Hanyu, 2003;Yogodzinski et al, 1995Yogodzinski et al, , 2001, the spatial and temporal association of adakites and high-Mg, magnesian and Nb-enriched dikes in West Junggar probably resulted from the following geological processes: (1) Adakitic melts formed by slab melting (Polat and Kerrich, 2001). Nb-enriched basalt (NEB) data of the Mesozoic Caribbean island arc are from Maury et al (1996) and Sajona et al (1996).…”

“…The rocks differ from the high-Nb basalts (Nb >20 ppm) that were suggested to have been derived from an adakite-metasomatized arc mantle (Defant and Drummond, 1993;Defant et al, 1992). For the formation of Nb-enriched rocks, three petrogenesis models were suggested (Defant et al, 1992;Sajona et al, 1994): melting of an OIB source, melting of the subducted slab and partial melting of a mantle metasomatized by adakitic melts. In West Junggar, some basalticandesitic dikes exhibit relatively high Nb contents (5.63-9.08 ppm), thus we referred these rocks as Nb-enriched dikes.…”

“…The NEB have a large variation of SiO 2 and consist of basaltic to basaltic-andesitic or dacitic lavas (Sajona et al, 1993(Sajona et al, , 1994. The rocks differ from the high-Nb basalts (Nb >20 ppm) that were suggested to have been derived from an adakite-metasomatized arc mantle (Defant and Drummond, 1993;Defant et al, 1992). For the formation of Nb-enriched rocks, three petrogenesis models were suggested (Defant et al, 1992;Sajona et al, 1994): melting of an OIB source, melting of the subducted slab and partial melting of a mantle metasomatized by adakitic melts.…”

Volcanism and geochemistry in Central America: Progress and problems

“…Panama has several Quaternary volcanic centers related to active subduction of the Nazca Plate [ de Boer et al, 1991;Defant et al, 1992]. Adakites occur in young Panamanian volcanoes [e.g.…”

Sr–Nd isotope geochemistry and tectonomagmatic setting of the Dehsalm Cu–Mo porphyry mineralizing intrusives from Lut Block, eastern Iran

“…However, since Nb and Ta are both highly incompatible in typical mantle assemblages and immobile during metasomatic events, their anomalies can, alternatively, be explained by the addition of slab components to The field of Cenozoic subducted oceanic crust-derived adakites was defined after Defant et al (1992), , Sajona et al (2000) and Aguillón-Robles et al (2001). The data for adakitic rocks directly derived from a thick lower crust are after Atherton and Petford (1993), Muir et al (1995) and Petford and Atherton (1996).…”