A Multistage Volcanic and Tectonic Evolution History on the High Plateau, Part of the Manihiki Plateau, Central Pacific

Thursday, 18 December 2014
Ricarda Pietsch and Gabriele Uenzelmann-Neben, Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Bremerhaven, Bremerhaven, Germany
For the Manihiki Plateau, a Large Igneous Province (LIP), a multistage volcanic emplacement history is revealed in new, multi channel high resolution seismic reflection data. Gathered during cruise So224 the profiles are distributed to study the initial emplacement of the High Plateau (HP), part of the Manihiki Plateau, as well as tectonic related processes at its margins. Extension of a previously defined seismostratigraphic model has allowed an identification of an intra-basalt reflector which has been formed by volcanism prior to the major emplacement during the early Cretaceous. We suggest that it represents the nucleus of the HP’s formation and conclude that the Manihiki Plateau is older than the proposed ~120 Ma. We have identified evidence that the plateau extended to the east and broke-up along the Manihiki Scarp prior to the second volcanic active phase. The south-western margin shows a stretched and rifted structure, which could be related to the separation of the Manihiki and Hikurangi Plateaus. Identification of extrusion centers associated with a third volcanic active period ending ~65 Ma ago and their spatial distribution hint on a shift of the emplacement mechanism from sources related to initial emplacement to tectonic induced volcanism at the margins. Later stage tectonic and volcanic reactivations occurred, which were concentrated in the south-western part of the HP.