Post-Subduction Tectonics of Sabah, Northern Borneo, Inferred From Surface Wave Tomography

Tim Greenfield* (Corresponding Author), Amy Gilligan, Simone Pilia, David G. Cornwell, Felix Tongkul, Sri Widiyantoro, Nicholas Rawlinson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

We use two-plane-wave tomography with a dense network of seismic stations across Sabah, northern Borneo, to image the shear wave velocity structure of the crust and upper mantle. Our model is used to estimate crustal thickness and the depth of the lithosphere-asthenosphere boundary (LAB) beneath the region. Calculated crustal thickness ranges between 25 and 55 km and suggests extension in a NW-SE direction, presumably due to back-arc processes associated with subduction of the Celebes Sea. We estimate the ?-factor to be 1.3?2, well below the initiation of seafloor spreading. The LAB is, on average, at a depth of 100 km, which is inconsistent with models that ascribe Neogene uplift to wholescale removal of the mantle lithosphere. Instead, beneath a region of Plio-Pleistocene volcanism in the southeast, we image a region 50?100 km across where the lithosphere has thinned to
Original languageEnglish
Article numbere2021GL096117
Number of pages12
JournalGeophysical Research Letters
Volume49
Issue number3
Early online date4 Feb 2022
DOIs
Publication statusPublished - 16 Feb 2022

Bibliographical note

Acknowledgments
We thank all those involved in the deployment of the nBOSS seismic array. BMKG and ITB facilitated the deployment of the Kalimantan array; without them, the stations could not have been deployed. nBOSS seismometers were provided by the University of Cambridge, University of Aberdeen, and SEIS-UK (Loan 1038). Many thanks go to Nick Harmon and Yingje Yang, both of whom provided vital software. Many figures were made using GMT (Wessel et al., 2019). TG is funded by a Leverhulme Early Career Research Fellowship (ECF-049). SP acknowledges support from the Natural Environmental Research Council (NERC) Grant NE/R013500/1 and from the European Union's Horizon 2020 Research and Innovation Program under Marie Skłodowska-Curie Grant Agreement 790203. Earth Sciences Cambridge publication number ESC-6308.

Keywords

  • surface wave tomography
  • Sabah
  • post-subduction
  • lithospheric structure
  • Borneo
  • LAB

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