Galapagos-OIB signature in southern Central America: mantle refertilization by arc-hot spot interaction.

Gazel, Esteban, Carr, Michael J., Hoernle, Kaj , Feigenson, Mark D., Szymanski, David, Hauff, Folkmar and van den Bogaard, Paul (2009) Galapagos-OIB signature in southern Central America: mantle refertilization by arc-hot spot interaction. Open Access Geochemistry, Geophysics, Geosystems, 10 (Q02S11). DOI 10.1029/2008GC002246.

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Abstract

[1] Although most Central American magmas have a typical arc geochemical signature, magmas in southern Central America (central Costa Rica and Panama) have isotopic and trace element compositions with an ocean island basalt (OIB) affinity, similar to the Galapagos-OIB lavas (e.g., Ba/La < 40, La/Yb > 10, 206Pb/204Pb > 18.8). Our new data for Costa Rica suggest that this signature, unusual for a convergent margin, has a relatively recent origin (Late Miocene ∼6 Ma). We also show that there was a transition from typical arc magmas (analogous to the modern Nicaraguan volcanic front) to OIB-like magmas similar to the Galapagos hot spot. The geographic distribution of the Galapagos signature in recent lavas from southern Central America is present landward from the subduction of the Galapagos hot spot tracks (the Seamount Province and the Cocos/Coiba Ridge) at the Middle American Trench. The higher Pb isotopic ratios, relatively lower Sr and Nd isotopic ratios, and enriched incompatible-element signature of central Costa Rican magmas can be explained by arc–hot spot interaction. The isotopic ratios of central Costa Rican lavas require the subducting Seamount Province (Northern Galapagos Domain) component, whereas the isotopic ratios of the adakites and alkaline basalts from southern Costa Rica and Panama are in the geochemical range of the subducting Cocos/Coiba Ridge (Central Galapagos Domain). Geological and geochemical evidence collectively indicate that the relatively recent Galapagos-OIB signature in southern Central America represents a geochemical signal from subducting Galapagos hot spot tracks, which started to collide with the margin ∼8 Ma ago. The Galapagos hot spot contribution decreases systematically along the volcanic front from central Costa Rica to NW Nicaragua.

Document Type: Article
Keywords: Central America, Ocean Island Basalt, Subduction, Galapagos hot spot, geochemistry, Sr-Nd-Pb isotopes
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
OceanRep > SFB 574 > C2
OceanRep > SFB 574
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/2008GC002246
ISSN: 1525-2027
Projects: Future Ocean, SFB574
Contribution Number:
ProjectNumber
SFB 574145
Expeditions/Models/Experiments:
Date Deposited: 06 Feb 2009 13:07
Last Modified: 23 Sep 2019 17:26
URI: http://oceanrep.geomar.de/id/eprint/6411

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