Publication Date:
2017-11-07
Description:
The age and origin of magmatic complexes along the Pacific Coast of Central America have important
implications for the origin and tectonic evolution of this convergent plate margin. Here we present
new 40Ar/39Ar laser age dates, major and trace element data, and initial Sr-Nd-Pb isotope ratios. The 124–
109 Ma tholeiitic portions of the Santa Elena complex formed in a primitive island arc setting, believed to
be part of the Chortis subduction zone. The geochemical similarities between the Santa Elena and Tortugal
alkaline volcanic rocks suggest that Chortis block may extend south of the Hess Escarpment. The Nicoya,
Herradura, Golfito, and Burica complexes and the tholeiitic Tortugal unit formed between 95 and 75 Ma
and appear to be part of the Caribbean Large Igneous Province, thought to mark the initiation of the
Gala´pagos hotspot. The Quepos and Osa complexes (65–59 Ma) represent accreted sections of an ocean
island and an aseismic ridge, respectively, interpreted to reflect part of the Gala´pagos paleo-hotspot track.
An Oligocene unconformity throughout Central America may be related to the mid-Eocene accretion of the
Quepos and Osa complexes.
Type:
Article
,
PeerReviewed
Format:
text
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