In situ Rb-Sr dating of slickenfibres in deep crystalline basement faults.
Mikael TillbergHenrik DrakeThomas ZackEllen KooijmanMartin J WhitehouseMats E ÅströmPublished in: Scientific reports (2020)
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.
Keyphrases
- mass spectrometry
- high performance liquid chromatography
- liquid chromatography
- ms ms
- neural network
- capillary electrophoresis
- room temperature
- gas chromatography
- tandem mass spectrometry
- air pollution
- molecular dynamics
- copy number
- healthcare
- upper limb
- genome wide
- health information
- high resolution mass spectrometry
- single molecule
- biofilm formation
- cancer therapy
- magnetic resonance
- social media
- solid phase extraction
- ionic liquid