Tag: Halmahera

Schematic tectonic reconstruction of the Halmahera SZI event (modified from Hall, 1996 and Hall and Smyth, 2008). Subduction of the Molucca Sea plate started close to a transform boundary, initiating the new Halmahera subduction zone. Shown are the new subduction zone (pink line), other active subduction zones (solid purple lines), and transform faults (red dashed lines).

The Halmahera subduction zone initiation (SZI) event – associated with the subduction of the Molucca Sea plate eastwards beneath the Philippine Sea plate – was previously estimated to have initiated at around 17–15 Ma (Baker & Malaihollo 1996; Hall, 1996), but more recent studies have alternatively suggested a younger age of ~10-7 Ma for SZI (Chandra & Hall, 2016; Hall & Spakman, 2015; Zhang et al. 2017). Given the evidence presented below, SZI must be older than 11 Ma. Considering a ~5 Myr delay (in line with Baker & Malaihollo 1996) we suggest ~15 Ma as our best-estimate for Halmahera SZI, but emphasise that this preference is likely to be controversial and may be revised downward if additional evidence demonstrates a disconnect between the oldest arc volcanism (on Obi Island) and later subduction beneath Halmahera. The type of SZI is also unclear, but could be ascribed to episodic subduction, as there is evidence of subduction along Halmahera from the Mesozoic to the Oligocene. That subduction ceased by the time of a regional plate boundary reorganisation at about 25 Ma, whereafter subduction initiated on the western side of the Molucca Sea plate, along the Sangihe arc (Hall and Smyth, 2008). Hall and Smyth (2008) suggested that Halmahera SZI was caused by locking of the Sorong fault zone along the southern edge of the Molucca Sea. Considering the broader geodynamic picture, Halmahera SZI occurred perhaps within ~20° of the Manus plume (Wu et al. 2016), and approximately above the edge of the Pacific LLSVP (i.e., along the edge of its surface projection, according to its present-day shape).

For more details on the geologic record, corresponding plate reconstruction, and seismic tomography, see the SZI Database.

• Creators: Fabio Crameri, Valentina Magni, Matthew Domeier, Ágnes Király, Grace Shephard
• This version: 17.06.2025
• License: Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
• Specific citation: These graphics from Crameri et al. (2020) are available via the open-access s-ink.org repository.
• Related reference: Crameri, F., V. Magni, M. Domeier, G.E. Shephard, K. Chotalia, G. Cooper, C. Eakin, A.G. Grima, D. Gürer, A. Király, E. Mulyukova, K. Peters, B. Robert, and M. Thielmann (2020), A transdisciplinary and community-driven database to unravel subduction zone initiation, Nature Communications, 11, 3750. doi:10.1038/s41467-020-17522-9

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