U-Pb zircon ages of the host rocks of the Juomasuo Au-Co-Cu deposit, northeastern Finland

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Nikkola , P , Mänttäri , I & Rämö , O T 2017 , ' U-Pb zircon ages of the host rocks of the Juomasuo Au-Co-Cu deposit, northeastern Finland ' , Bulletin of the Geological Society of Finland , vol. 89 , pp. 20-34 . https://doi.org/10.17741/bgsf/89.1.002

Title: U-Pb zircon ages of the host rocks of the Juomasuo Au-Co-Cu deposit, northeastern Finland
Author: Nikkola, Paavo; Mänttäri, Irmeli; Rämö, O. Tapani
Contributor: University of Helsinki, Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland
University of Helsinki, Department of Geosciences and Geography
Date: 2017
Language: eng
Number of pages: 15
Belongs to series: Bulletin of the Geological Society of Finland
ISSN: 0367-5211
URI: http://hdl.handle.net/10138/225144
Abstract: U-Pb zircon single grain dating using the LA-MC-ICP-MS technique was utilized to determine the age of the host rocks of the Juomasuo Au-Co-Cu deposit located in the late Archean Kuusamo supracrustal belt. Even though the dated samples have diverse geochemical signatures that imply felsic volcanic and sedimentary precursors, the U-Pb data revealed heterogeneous detrital zircon populations for all samples. The host rocks are thus considered to belong to reworked sedimentary/volcano-sedimentary sequences. The maximun depositional ages of the samples fall in the 2.75-2.65 Ga age window, and no Paleoproterozoic ages were recovered in the examined zircon grains (151 analytical spots in total). In addition, a younger population (2.65-2.60 Ga) of internally featureless, BSE-pale/CL-dark zircon and zircon domains, was found in the mineralized sequences. These homogenized zircon grains resemble zircon formed in postmagmatic solid-state processes, in which zircon is recrystallized in metamorphic-hydrothermal conditions. This metamorphic-hydrothermal event most probably occurred in the original provenance area of the metasedimentary rocks.
Subject: U-Pb geochronology
zircon
LA-MC-ICP-MS
Juomasuo
Finland
ISOTOPE
RECRYSTALLIZATION
GEOCHRONOLOGY
CONSTRAINTS
EVOLUTION
GROWTH
1171 Geosciences
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