| Ocean: | Indian |
| Spreading center type: | Extinct microplate spreading ridge |
| Time of cessation: | After chron C21n, 47.9 Ma (Matthews et al., 2016) |
| Subsequent active spreading center: | Present day configuration of the Southeast Indian Ridge |
Matthews et al. (2016) recently identified an extinct oceanic microplate in the Indian Ocean, close to the Ninetyeast Ridge on the northern side of the Southeast Indian Ridge (SEIR). There are limited magnetic isochrons identified on the extinct microplate, however magnetic anomaly picks in the region of the plate isolate the time of cessation to after chron C21n (Matthews et al., 2016).
Identification of the extinct microplate is strongly supported by the tectonic fabric of the surrounding ocean floor, which is evident in the most recent vertical gravity data (Sandwell et al., 2014). Fracture zones and abyssal hill orientation show that a portion of the crust has been rotated relative to the crust produced at the Antarctica-India plate boundary (Matthews et al., 2016).
Matthews et al. (2016) propose that the Mammerickx microplate may have formed at a time of fast-spreading rates in the Indian Ocean (over 50 mm/yr), that was likely to have been contemporaneous with India-Eurasia collision. They argue that proximity to the Kerguelen plume may have influenced the development of the microplate (Matthews et al., 2016) and that spreading may have ceased as the plate moved away from the plume.
Matthews, K. J., Müller, R. D., and Sandwell, D. T., 2016, Oceanic microplate formation records the onset of India-Eurasia collision, Earth and Planetary Science Letters, v. 433, p. 204-214, doi:10.1016/j.epsl.2015.10.040
Sandwell, D., Müller, R. D., Smith, W. H. F., Garcia, E. S., Francis, R., 2014, New global marine gravity model from CryoSat-2 and Jason-1 reveals buried tectonic structure. Science, v. 346, no. 6205, p. 65-67.
