Reconstructing craton-scale tectonic events via in situ Rb-Sr geochronology of poly-phased vein mineralization

Fault- and fracture-hosted multi-stage mineral assemblages that formed by fracture reactivation and fluid migration, constitute archives of the tectonic evolution of Precambrian cratons. Complex intergrowth patterns of these mineral records often hinder absolute dating of mineralization events for geological models. We apply LA-ICP-MS/MS in situ Rb-Sr dating of single crystal growth zones in sub-mm-wide vein mineralization assemblages including illite, K-feldspar, albite, calcite, mica, zeolites, fluorite and/or epidote at three Palaeoproterozoic crystalline bedrock sites over 300 km apart in the Fennoscandian Shield. The dating campaign reveals multiple age clusters between ca. 1757 +/- 15 and 355 +/- 12 Ma correlating with fluid flow and fracture reactivation events initiated by far-field orogens and their foreland basin evolution. This new approach for reconstructing geological histories of Precambrian cratons connects micro-scale age determinations of different mineral growth zones in fractures with regional-scale crustal dynamic responses to tectonic events.

Automated summary

By using LA-ICP-MS/MS in situ Rb-Sr dating, this study reveals multiple age clusters between ca. 1757 +/- 15 and 355 +/- 12 Ma in mineralization assemblages at three Palaeoproterozoic crystalline bedrock sites, linking fluid flow and fracture reactivation events with far-field orogens and foreland basin evolution. This new approach connects micro-scale age determinations with regional-scale crustal dynamic responses, providing insights into the tectonic evolution of Precambrian cratons.