LAUSR

The Aden-Owen-Carlsberg triple junction is the place where Arabia, Somalia, and India meet in the Arabian Sea (NW Indian Ocean). Here we present a new seismic data set crossing a key structure of the triple junction, namely, the Beautemps-Beaupré pull-apart basin at the southern end of the Owen Fracture Zone. The seismic data set is tied to Ocean Drilling Program Leg 117 Sites at the top of the Owen Ridge, which provides a detailed tectono-stratigraphic framework since the Late Miocene. We show that the triple junction configuration has been disturbed by a major kinematic change at ~8 Ma and since then experienced a series of transient structural adjustments. A major structural episode is recorded at 2.4 Ma, expressed by the opening of the Beautemps-Beaupré Basin and the uplift of its southern flank (the Beautemps-Beaupré Ridge). This episode is coeval with the formation of the present-day Owen Fracture Zone and must be considered as a part of a major structural reorganization of the entire India-Arabia plate boundary up to the Makran subduction zone. This 2.4-Myr-old geological episode is unrelated to any significant kinematic change, leaving questions over its driving mechanism.