EGU24-8155, updated on 08 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Insights into Asymmetric Back-Arc Basin Formation in the Mariana Trough at 17°N from Traveltime Tomography

Helene-Sophie Hilbert1, Anke Dannowski1, Ingo Grevemeyer1, Christian Berndt1, Shuichi Kodaira2, Gou Fujie2, and Narumi Takahashi2
Helene-Sophie Hilbert et al.
  • 1GEOMAR Helmholtz Centre for Ocean Research Kiel, Marine Geodynamics, Kiel, Germany (
  • 2Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama 236-0001, Japan

The Mariana Trough is the youngest back-arc basin in a series of basins and arcs that developed behind the Izu-Bonin-Mariana subduction zone in the western Pacific. In addition to active seafloor spreading, the Mariana Trough also exhibits a pronounced asymmetry, with the spreading axis closer to the Mariana Arc. The formation and development of this back-arc basin and its predecessor is controlled by a complex interplay of temporal mantle heterogeneities, subduction dynamics of the Pacific Plate and large-scale tectonics since ~50 Ma. Here, we present new insights into the development of the central Mariana Trough at ~17°N from analyses of a 2-D P-wave traveltime tomography together with high-resolution bathymetric data. The refraction and wide-angle reflection data have been recorded by R/V KAIYO (JAMSTEC) on 41 ocean bottom seismometers (OBSs) along a 250 km profile in 2003. The results allow a subdivision of the Mariana Trough into different stages of back-arc basin opening and seem to imply a transition from symmetric rifting to asymmetric seafloor spreading. Fast-velocities in the lower crust in the rifting domain indicate that magma generation and crust formation was highly affected by hydrous melting from the subducting slab during this stage. This slab contribution decreases with the onset of active seafloor spreading due to a change in mantle flow and hence seems to be accompanied by a tectonic rearrangement of the eastern side of the basin.

How to cite: Hilbert, H.-S., Dannowski, A., Grevemeyer, I., Berndt, C., Kodaira, S., Fujie, G., and Takahashi, N.: Insights into Asymmetric Back-Arc Basin Formation in the Mariana Trough at 17°N from Traveltime Tomography, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8155,, 2024.

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