The Paleoproterozoic Kandalaksha-Kolvitsa Gabbro-Anorthosite Complex (Fennoscandian Shield): New U–Pb, Sm–Nd, and Nd–Sr (ID-TIMS) Isotope Data on the Age of Formation, Metamorphism, and Geochemical Features of Zircon (LA-ICP-MS)

Ekaterina N Steshenko,Tamara B Bayanova,Pavel A Serov

doi:10.3390/min10030254

Ekaterina N Steshenko, Tamara B Bayanova + Show 1 more

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https://doi.org/10.3390/min10030254

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Journal: Minerals	Publication Date: Mar 10, 2020
Citations: 3	License type: CC BY 4.0

Affiliation: Kola Science Centre, Geological Institute

Abstract

The paper provides new U–Pb, Sm–Nd, and Nd–Sr isotope-geochronological data on rocks of the Paleoproterozoic Kandalaksha-Kolvitsa gabbro-anorthosite complex. Rare earth element (REE) contents in zircons from basic rock varieties of the Kandalaksha-Kolvitsa area were analyzed in situ using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Plots of REE distribution were constructed, confirming the magmatic origin of zircon. Temperatures of zircon crystallization were estimated using a Ti-in-zircon geochronometer. The U–Pb method with a 205Pb artificial tracer was first applied to date single zircon grains (2448 ± 5 Ma) from metagabbro of the Kolvitsa massif. The U–Pb analysis of zircon from anorthosites of the Kandalaksha massif dated the early stage of the granulite metamorphism at 2230 ± 10 Ma. The Sm–Nd isotope age was estimated on metamorphic minerals (apatite, garnet, sulfides) and whole rock at 1985 ± 17 Ma (granulite metamorphism) for the Kolvitsa massif and at 1887 ± 37 Ma (high-temperature metasomatic transformations) and 1692 ± 71 Ma (regional fluid reworking) for the Kandalaksha massif. The Sm–Nd model age of metagabbro was 3.3 Ga with a negative value of εNd = 4.6, which corresponds with either processes of crustal contamination or primary enriched mantle reservoir of primary magmas.

Highlights

Gabbro-anorthosite complexes occur in almost every ancient Hadean craton in the world (Pilbara and Yilgarn in Australia, Fiskenaesset in Greenland, Karnataka in India, etc.) [1,2,3]
Two zircon morphotypes were separated from metagabbro of the Kolvitsa massif to study Rare earth element (REE) distribution in zircon and to provide precise U–Pb dating
The U–Pb analysis on single zircon grains was applied for the first time, using a 205 Pb artificial tracer to date zircons from metagabbro of the Kolvitsa massif [36]

Summary

Introduction

Gabbro-anorthosite complexes occur in almost every ancient Hadean craton in the world (Pilbara and Yilgarn in Australia, Fiskenaesset in Greenland, Karnataka in India, etc.) [1,2,3]. Gabbro-anorthosite magmatism is widespread from the Mesoarchean to the Paleoproterozoic (Figure 1) and associated with the formation of strategic mineral deposits (Cu–Ni, Ti–V, Pt–Pd, etc.) [4]. The Kolvitsa gabbro-anorthosite massif is located in the south of the Kola Peninsula, in the Kolvitsa. The Kandalaksha-Kolvitsa area is located in the southern part of the Lapland Granulite. The. Kandalaksha-Kolvitsa gabbro-anorthosite area tends to attract much attention for isotope-geochemical research as an object promising for platinum group elements (PGE) ores. It is suggested to have a magmatic (plume?) origin, since rocks of the Kandalaksha-Kolvitsa zone have similar isotope-geochronological features with layered PGE intrusions in the Baltic Shield (Fedorovo-Pana massif, Monchetundra massif, etc.) [6]. This paper focused on the dating of the formation and the further metamorphic reworking of the Kandalaksha and Kolvitsa anorthosite massifs. Several stages of metamorphism were identified in the Kandalaksha-Kolvitsa area [9]

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