The eastern boundary of Sveconorwegian reworking in the Baltic Shield,defined by 40Ar/39Ar geochronology across the southernmost Sveconorwegian Province
Summary, in Swedish
was disturbed. Several biotite samples record ages in the interval 0.9–1.4 Ga, reflecting excess Ar components. East of the Sveconorwegian Province, in the Blekinge-Bornholm Province, hornblende and mica apparent ages spread between 1.13 and 1.41 Ma, implying that neither mineral underwent complete
Sveconorwegian resetting. The data pattern reflects that the Eastern Segment experienced slow cooling (∼3 °C/ Ma) from peak metamorphism of 800–700 °C at 980–960 Ma to 900 Ma, when significant cooling though greenschist-facies conditions set in (∼26 °C/Ma). This cooling was related to tectonically driven extension, accommodated by greenschist-facies shear zones along the eastern boundary zone.
- cooling age
- 40Ar/39Ar thermochronology
- ISSN: 0301-9268