What the ca. 1.83 Ga gedrite-cordierite schists in the crystalline basement of Lithuania tell us about the late Palaeoproterozoic accretion of the East European Craton

ABSTRACT

In the western East European Craton (EEC), southern Lithuania, a suite of fine-grained, thinly bedded rocks of unusual composition has been shown to have originally comprised intermediate and felsic volcanic rocks. They extruded at ca. 1.83 Ga and were hydrothermally altered prior to metamorphism, which converted them into garnet-, gedrite-, anthophyllite-, staurolite- and cordierite-bearing schists. After the rocks have experienced a 630°C and 7 kbar metamorphism, they were uplifted to 15 km (5 kbar) probably at ca. 1.73 Ga. They were reheated to 640°C at ca. 1.50 Ga (monazite age). The monazite age of ca. 1.50 Ga is coeval with the emplacement of the neighboring 1.50 Ga Anorthosite-Mangerite-Charnockite-Granite (AMCG) Mazury complex. The ca. 1.83 Ga volcanic suites in Lithuania and northern Poland, together with the Oskarshamn-Jönköping belt (OJB) in south-central Sweden, may belong to the same chain of volcanic island arcs, and thus provide information on the evolution of the entire western EEC. The ca. 1.50 Ga metamorphic reworking and the replacement of the Mazury AMCG suite may have been triggered by the Danopolonian orogeny further west and, at a larger scale, accretion of the continental margin of Columbia.

KEYWORDS:

• Gedrite
• anthophyllite
• East European Craton (EEC)
• hydrothermal alteration
• metamorphism

Acknowledgments

The research of Siliauskas and Prusinskiene was supported by the Nature Research Centre doctoral study funds. For the zircon study, the authors thank the SYNTHESYS 3 support [project SE-TAF-7040]; the grant agreement number is 312253. The authors are grateful to Lev Iliynsky and Kerstin Linden from the NORDSIM laboratory at the Swedish Museum of Natural History and Lidia Jeżak from the EPMA laboratory at Warsaw University for assistance with zircon and monazite dating. We also thank Prof. Ray Macdonald for the language corrections. The constructive and helpful reviews of Joakim Mansfeld and Leonid Shumlyanskyy let us considerably improve the manuscript quality. This is NORDSIM contribution No 575.

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No potential conflict of interest was reported by the authors.

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Funding

The research of Siliauskas and Prusinskiene was supported by the Nature Research Centre doctoral study funds. For the zircon study, the authors thank the SYNTHESYS 3 support [project SE-TAF-7040]; the grant agreement number is 312253.