Tectonic strain recorded by magnetic fabrics (AMS) in plutons, including Mt Kinabalu, Borneo: A tool to explore past tectonic regimes and syn-magmatic deformation

Tectonic strain commonly overprints magmatic fabrics in AMS (Anisotropy of Magnetic Susceptibility) data for plutonic rocks produced by both compressional and extensional regimes. Mt Kinabalu, Borneo, is a composite pluton with an exceptional vertical range of exposure and clearly defined internal contacts. We show that tectonic fabrics are recorded pervasively throughout the intrusion, even near contacts, and present a workflow distinguishing compressive and extensional syn-magmatic deformation. At Mt Kinabalu this reveals a pervasive tectonic fabric indicating NW-SE Miocene extension in Borneo at 7.9–7.3 Ma, later than previously recognised, oriented NW-SE at 319° ±13.1°. Comparing data from Mt Kinabalu with data from globally distributed studies shows that tectonic strain is commonly recorded by plutons. Therefore, AMS fabric can be used to identify the syn-magmatic tectonic setting and combined with both geochronology and evidence for paleomagnetic rotation to provide a powerful tool for accurate determination of syn-magmatic tectonic regimes and strain orientations within temporal frameworks.

Details

Publication status:
Published
Author(s):
Authors: Burton-Johnson, Alex ORCIDORCID record for Alex Burton-Johnson, Macpherson, C.G., Muraszko, J.R., Harrison, R.J, Jordan, Tom A. ORCIDORCID record for Tom A. Jordan

On this site: Alex Burton-Johnson, Tom Jordan
Date:
1 February, 2019
Journal/Source:
Journal of Structural Geology / 119
Page(s):
50-60
Digital Object Identifier (DOI):
https://doi.org/10.1016/j.jsg.2018.11.014