The southeast Mariana forearc rift
Investigating the magma genesis of Miocene lavas from the southernmost Marianas to further comprehend subduction and mantle processes occurring beneath the forearc.
The southernmost Marianas represents the southern end of the Izu-Bonin-Mariana (IBM) intraoceanic arc. The southeast Mariana Eocene forearc stretched ~ 5 Ma ago to accommodate opening of the Mariana Trough, forming the SE Mariana Forearc Rift (SEMFR) at ~ 2- 4 Ma. SEMFR is unique in IBM because it overlies the very shallow part of the downgoing plate, where mantle melting rarely occurs.
Because spreading of the fore-arc occurs above a shallow subducted Pacific plate that dehydrates efficiently, the upper fore-arc lithosphere is broadly stretched over several kilometers. This type of spreading is unlike spreading at mid-ocean ridge or at back-arc basin spreading centers, where mantle melts and spreading are focused along a narrow axis. Diffuse spreading may have taken place at the onset of a subduction zones, as the downgoing plate begins to sink into the asthenospheric mantle. |
Further readings
Martinez F., Stern R.J., Kelley K., Ohara Y., Sleeper J.D., Ribeiro J., Brounce M. (2018) Diffuse extension of the southern Mariana margin, Journal of Geophysical Research: Solid Earth, DOI: 10.1002/2017JB014684.
Ribeiro J.M., Stern R.J., Kelley K.A., Shaw A., Martinez F., Ohara Y. (2015) Composition of the slab-derived fluids released beneath the Mariana forearc: evidence for shallow dehydration of the subducting plate.Earth and Planetary Science Letters, doi: 10.1016/j.epsl.2015.02.018.
Ribeiro J.M., Ishizuka O., Stern R.J., Kelley K.A., Anthony E.Y., Ren M., Ohara Y., Reagan M., Girard G., Bloomer S. (2013) Geodynamic evolution of a forearc rift in the southernmost Mariana intraoceanic Arc. Island Arc 22, 453-476, doi:10.1111/iar.12039.
Martinez F., Fryer P., Sleeper J., Stern R., Kelley K., Ohara Y., Ribeiro J.M. (2014) Hydrous lithosphere and diffuse crustal accretion and tectonics in the southern Mariana margin: a possible analog for subduction zone infancy, AGU Fall meeting 2014.
Stern R.J., Martinez F., Ribeiro J.M., Reagan M., Ohara Y., Kelley K., Ishizuka O. (2014) The Southeast Mariana Forearc Rift: A Modern Analogue for Forearc Extension during Subduction Initiation, AGU Fall meeting 2014.
Ribeiro J.M., Stern R.J., Kelley K.A., Shaw A., Martinez F., Ohara Y. (2015) Composition of the slab-derived fluids released beneath the Mariana forearc: evidence for shallow dehydration of the subducting plate.Earth and Planetary Science Letters, doi: 10.1016/j.epsl.2015.02.018.
Ribeiro J.M., Ishizuka O., Stern R.J., Kelley K.A., Anthony E.Y., Ren M., Ohara Y., Reagan M., Girard G., Bloomer S. (2013) Geodynamic evolution of a forearc rift in the southernmost Mariana intraoceanic Arc. Island Arc 22, 453-476, doi:10.1111/iar.12039.
Martinez F., Fryer P., Sleeper J., Stern R., Kelley K., Ohara Y., Ribeiro J.M. (2014) Hydrous lithosphere and diffuse crustal accretion and tectonics in the southern Mariana margin: a possible analog for subduction zone infancy, AGU Fall meeting 2014.
Stern R.J., Martinez F., Ribeiro J.M., Reagan M., Ohara Y., Kelley K., Ishizuka O. (2014) The Southeast Mariana Forearc Rift: A Modern Analogue for Forearc Extension during Subduction Initiation, AGU Fall meeting 2014.