Article ID Journal Published Year Pages File Type
4722664 Precambrian Research 2015 13 Pages PDF
Abstract

•We obtained precise U–Pb baddeleyite ages for the Rincón del Tigre and the Huanchaca intrusions.•The 1110–1112 Ma age for both defines a LIP-mantle plume event in SW Amazonia.•The LIP-mantle plume event is potentially linked with an evolving Grenville margin.•There is a tight age match with intraplate magmatism in other crustal blocks.

High quality U–Pb (ID-TIMS) baddeleyite ages define the timing of crystallization of the Rincón del Tigre layered intrusion (1110 ± 2 Ma) and the Huanchaca mafic suite (1112 ± 2 Ma) in the Bolivian Precambrian shield – SW portion of the Amazonian Craton. The identical ca. 1110–1112 Ma ages obtained for each (about 500 km apart) suggest these belong to a previously unrecognized LIP. The large area of distribution and the intraplate geochemistry for the 1110 Ma Huanchaca–Rincón del Tigre rocks support a relationship with mantle plume activity pre-dating Rodinia breakup. Contemporary anorogenic magmatism in Amazonia is probably linked to crustal melting caused by the LIP. The newly identified 1110 Ma LIP has a tight age match with intraplate magmatism in the Congo, Kalahari and Indian cratons, and the Keweenawan event of central Laurentia among others. While a reconstruction history of Amazonia and Laurentia is still a matter of debate on paleomagnetic grounds, a reconstruction link with other crustal blocks remains possible.

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Physical Sciences and Engineering Earth and Planetary Sciences Geochemistry and Petrology
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