Age and structural constraints on the tectonic evolution of the Paleoproterozoic Saimaa orocline in Fennoscandia

•Metasediments deposited at 1.89–1.87 Ga are an important post-D2 marker horizon.•All 1.90–1.88 Ga arc rocks in Finland have formed in one linear arc system.•Saimaa orocline: A continuation of paired Bothnian oroclines (1.87–1.86 Ga).•Saimaa orocline: A radical reinterpretation for the southern Finland orogen.•Shifting deformation patterns with different ages preclude unidirectional tectonics.