Internal structure and emplacement mechanism of composite plutons: Evidence from Mt Kinabalu, Borneo

Burton-Johnson, A.; Macpherson, C.; Hall, R.

Abstract

The internal structure and emplacement mechanisms of composite plutons are investigated using new field data from the composite Late Miocene granitic intrusion of Mt Kinabalu in northern Borneo. The pluton was emplaced in the upper to middle crust in the Late Miocene at the contact between the ultramafic basement and sedimentary cover rocks. Structural data indicate that emplacement occurred during regional NNW–SSE-oriented extension, challenging tectonic models that involve contemporaneous regional compression. The six major units forming the pluton were accommodated by upward flexure of the cover rocks with most magma pulses emplaced successively beneath their predecessors. However, the irregular 3D internal structure of the pluton also reflects preferential emplacement of successive units along the granite–country rock contact of previous units in preference to the basement–cover rock contact exploited by the initial units. This study highlights the complex emplacement mechanisms and internal structure of composite intrusions and assesses how they differ from models of tabular emplacement.

Citation

Burton-Johnson, A., Macpherson, C., & Hall, R. (2017). Internal structure and emplacement mechanism of composite plutons: Evidence from Mt Kinabalu, Borneo. Journal of the Geological Society, 174(1), 180-191. https://doi.org/10.1144/jgs2016-041

• Journal Article Type: Article
• Acceptance Date: Jul 21, 2016
• Online Publication Date: Sep 22, 2016
• Publication Date: Jan 1, 2017
• Deposit Date: Jul 25, 2016
• Publicly Available Date: Sep 22, 2017
• Journal: Journal of the Geological Society
• Print ISSN: 0016-7649
• Electronic ISSN: 2041-479X
• Publisher: The Geological Society
• Peer Reviewed: Peer Reviewed
• Volume: 174
• Issue: 1
• Pages: 180-191
• DOI: https://doi.org/10.1144/jgs2016-041
• Public URL: https://durham-repository.worktribe.com/output/1400466