A multistage volcanic and tectonic formation history of the Manihiki Plateau, central Pacific

• Main Authors: Pietsch, Ricarda, Uenzelmann-Neben, Gabriele
• Format: Conference Object
• Language: unknown
• Published: 2015
• Subjects: Danger Islands
• Online Access: https://epic.awi.de/id/eprint/37821/; https://hdl.handle.net/10013/epic.45452

The Manihiki Plateau, a Large Igneous Province (LIP), is the proposed center piece of Ontong Java Nui, a so called Super Large Igneous Province in the central Pacific. For the Manihiki Plateau, a multistage volcanic and tectonic emplacement history is revealed in new, multi-channel high resolution seismic reflection data. Gathered during cruise So224 (2012), the profiles are distributed to study the initial emplacement and tectonic related processes at the margins of the High Plateau (HP), and the Western Plateaus, two subprovinces of the Manihiki Plateau. Improved data quality has allowed for an identification of an intra-basement reflection sequence, which was formed by volcanism prior to the major emplacement during the early Cretaceous. Restricted to the southern part of the High Plateau, we suggest that it represents the nucleus of the HP’s formation and conclude that the Manihiki Plateau is older than the proposed ~125 Ma. We have identified evidence that the plateau was extended to the east during that stage and later broke-up along the Manihiki Scarp during the main emplacement period (125-110 Ma). Further break-up occurred between the Hikurangi and Manihiki Plateaus and resulted in stretched and rifted structures at the south-western margin. The Western Plateaus were separated at the Danger Islands troughs, an en enchelon depression system, which resulted in different morphologies and seismic facies. Secondary volcanism lasted until ~65 Ma with a spatial distribution that hint on a shift of the emplacement mechanism from sources related to initial emplacement to tectonic induced volcanism at the margins. The south-western part of the High Plateau has still been tectonically active after the end of the secondary volcanic period. These findings contribute to a detailed understanding of the evolution of a Large Igneous Province including multiple distinct volcanic and tectonic stages.