Discussion on the Rb-Sr age determination of Porto granite: Implications of the 87Rb decay constant [Discussão sobre a determinação da idade do granito do Porto pelo sistema Rb-Sr: Implicações do valor da constante de decaimento do 87Rb]

• Type: Article in International Scientific Journal
• Date: 2015

Authors

Maria Ângela Almeida (Author) FCUP; Santos, JF (Author) Other; Noronha, F (Author) Other

Journal

Title: Comunicações Geológicas

Vol. 102

Pages: 143-145

ISSN: 0873-948X

Publisher: LNEG - Laboratório Nacional de Energia e Geologia

Indexing

Scopus - 1 Citation

Other information

Authenticus ID: P-00M-WVC

Abstract (EN): The determination of absolute ages by isotopic systematics is an indispensable datum to constrain the petrogenesis and evolution conditions of a rock, being a contribution to a better characterization of the geological and tectonic settings. The granitic rocks of Porto region have been the object of several isotopic and geochronological studies that have allowed a comparative approach by different methods, namely U-Pb, Rb-Sr and Sm-Nd. The age determination of the Porto peraluminous two-mica granite by the Rb-Sr systematics based on recent estimates of the 87Rb decay constant, assumed as more accurate than the constant usually recommended, suggests the age of 311±7 Ma for the emplacement of the Porto granite. This age is in agreement with the affiliation of Porto granite to the group of syn-tectonic granites related with the third Hercynian deformation phase. The present results are more concordant with the U-Pb ages reported in previous works for zircon and monazite of the same granite. © 2015 LNEG - Laboratório Nacional de Geologia e Energia IP.

Language: Portuguese

Type (Professor's evaluation): Scientific