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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Ar-49/Ar-39 geochronological evidence for multiple magmatic events during the emplacement of Tapira alkaline-carbonatite complex, Minas Gerais, Brazil

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Author(s):
Conceicao, Fabiano T. [1] ; Vasconcelos, Paulo M. [2] ; Godoy, Leticia H. [1] ; Navarro, Guillermo R. B. [1]
Total Authors: 4
Affiliation:
[1] UNESP Univ Estadual Paulista, Inst Geociencias & Ciencias Exatas, Rio Claro - Brazil
[2] Univ Queensland, Sch Earth Sci, Brisbane, Qld - Australia
Total Affiliations: 2
Document type: Journal article
Source: Journal of South American Earth Sciences; v. 97, JAN 2020.
Web of Science Citations: 0
Abstract

The Alto Parnaiba Igneous Province (APIP) is a voluminous magmatic province composed of various alkaline-carbonatite complexes emplaced in the Brasilia Mobile Belt during the Cretaceous. Relative timing of emplacement of silicate and carbonate magmas in most of these complexes remains mostly unresolved due to conflicting geochronological results. To determine the duration of magmatism and to test the possible existence of multiple magmatic events, we employ Ar-40/Ar-39 phlogopite single crystal dating to determine the history of magma emplacement at the Tapira alkaline-carbonatite complex, Minas Gerais, Brazil. The new single crystal data indicate at least two magmatic events during the emplacement of this complex, the first at > 96.2 +/- 0.8 Ma and the second at 79.15 +/- 0.6 Ma. The first igneous event was responsible for emplacement of the silicate plutonic series, while the second event corresponds to the emplacement of primarily carbonatitic magmas, generating metasomatic phlogopite alteration in bebedourites. The ages of intrusion and cooling of the alkaline-carbonatite complexes in the APIP must be investigated in other complexes to determine if intrusion intervals of similar to 17 Ma or more are common regionally. Protracted intrusive events, if related to magma generation by passage of South America over a stationary Trindade plume, requires complex ponding and lateral magma flow below a slow-moving continent. (AU)