In situ Rb-Sr dating of slickenfibres in deep crystalline basement faults

Establishing temporal constraints of faulting is of importance for tectonic and seismicity reconstructions and predictions. Conventional fault dating techniques commonly use bulk samples of syn-kinematic illite and other K-bearing minerals in fault gouges, which results in mixed ages of repeatedly r...

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Bibliographic Details
Published in:Scientific reports 2020-01, Vol.10 (1), p.562-562, Article 562
Main Authors: Tillberg, Mikael, Drake, Henrik, Zack, Thomas, Kooijman, Ellen, Whitehouse, Martin J., Åström, Mats E.
Format: Article
Language:English
Subjects:
704/2151/209
704/2151/213
Calcite
Crystalline rocks
Den föränderliga jorden
Earth and Related Environmental Sciences
Fault lines
Geovetenskap och miljövetenskap
Humanities and Social Sciences
Illite
Isotopes
Kinematics
Mass spectrometry
Mass spectroscopy
Minerals
multidisciplinary
Natural Science
Naturvetenskap
Orogeny
Radiometric dating
Rubidium-strontium dating
Science
Science (multidisciplinary)
The changing Earth
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Summary:Establishing temporal constraints of faulting is of importance for tectonic and seismicity reconstructions and predictions. Conventional fault dating techniques commonly use bulk samples of syn-kinematic illite and other K-bearing minerals in fault gouges, which results in mixed ages of repeatedly reactivated faults as well as grain-size dependent age variations. Here we present a new approach to resolve fault reactivation histories by applying high-spatial resolution Rb-Sr dating to fine-grained mineral slickenfibres in faults occurring in Paleoproterozoic crystalline rocks. Slickenfibre illite and/or K-feldspar together with co-genetic calcite and/or albite were targeted with 50 µm laser ablation triple quadrupole inductively coupled plasma mass spectrometry analyses (LA-ICP-MS/MS). The ages obtained disclose slickenfibre growth at several occasions spanning over 1 billion years, from at least 1527 Ma to 349 ± 9 Ma. The timing of these growth phases and the associated structural orientation information of the kinematic indicators on the fracture surfaces are linked to far-field tectonic events, including the Caledonian orogeny. Our approach links faulting to individual regional deformation events by minimizing age mixing through micro-scale analysis of individual grains and narrow crystal zones in common fault mineral assemblages.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-019-57262-5