U–Pb zircon ages of the host rocks of the Juomasuo Au–Co–Cu deposit, northeastern Finland
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 s...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Geological Society of Finland
2017-09-01
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| Series: | Bulletin of the Geological Society of Finland |
| Subjects: | |
| Online Access: | http://www.geologinenseura.fi/bulletin/Volume89/Bulletin_vol89_1_20-34_2017_Nikkola-etal.pdf |
| Summary: | 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. |
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| ISSN: | 0367-5211 1799-4632 |