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

Bulletin of the Geological Society of Finland

关键词: U–Pb geochronology;    zircon;    LA-MC-ICP-MS;    Juomasuo;    Finland;   

DOI  :  10.17741/bgsf/89.1.002

来源: DOAJ

【 摘 要 】

The Salittu Formation is one of the few metavolcanic successions in the 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.

【 授权许可】

Unknown