1 Geology, Department of Geosciences and Natural Resource Management, Faculty of Science, Københavns Universitet2 University of Helsinki3 University of Leeds4 Geology, Department of Geosciences and Natural Resource Management, Faculty of Science, Københavns Universitet
an example from Tampere Schist Belt, Finland
We present field observations from the Palaeoproterozoic volcano-sedimentary Tampere palaeobasin, where the primary structures have been exceptionally well preserved. We use the observations to construct a new tectonic model for the southeastern margin of the Tampere basin during its inversion and subsequent closure. The observed volcano-sedimentary and structural features suggest a change in the local structural style from thick-skinned inversion to thin-skinned thrusting, in order to accommodate the crustal shortening during basin closure. Furthermore, it is suggested that there is a genetic relationship between the interpreted palaeothrusts and the sulphide-bearing schist horizons in the study area. On a more general note, the results infer that presently subvertical mineralised shear zones may have originally been gently dipping, further suggesting that the mineralised fluids may not necessarily have been sourced from great depths (i.e. from deep within the basement).
Journal of the Geological Society, 2014, Vol 171, Issue 5, p. 659-671