The Link Between Ontong-Java and Louisville Revealed in the West Pacific
Abstract
In hotspots, the initial rising plume head is thought to generate a large igneous province, while the plume tail generates an age progressive volcanic chain as the plate moves overhead. However, the Ontong-Java Plateau (OJP), the most voluminous large igneous province, is problematic as it not directly connected with a clear age-progressive volcanic chain. In order to make a match, existing absolute plate motion (APM) models require ~1200 km of latitudinal plume motion to link OJP to Louisville, the nearest hotspot (1). Unfortunately, the oldest portion of the Louisville hotspot (>80 Ma) was subducted, so it is impossible to directly test if it does trace back to the ~120 Ma OJP, or if motion occurred. Furthermore, plume motion at that scale is not consistent with the predicted minimal plume motion for Louisville, back to at least 70 Ma, as deduced from paleomagnetic data and the unchanging distance between coeval seamounts in the Louisville and Rurutu hotspot chains over that timespan (2,3). However, a combination of recent and new isotopic compositions and 40Ar/39Ar ages (3,4) inspires an alternate interpretation of Pacific APM for the 80-100 Ma timeframe. These new data fill a compositional gap and strengthen a morphological continuation of the seamount chain produced by the Rurutu hotspot into the Wake seamounts. These seamounts, together with the older section of the Samoan hotspot track, are then used to constrain APM between 80-100 Ma. By virtue of this new APM model's increased north-south motion, the OJP originally erupted in the same area as present-day Louisville, consistent with a Louisville hotspot origin for the OJP.
(1) Chandler et al., 2012, 10.1016/j.epsl.2012.03.017 (2) Koppers et al., 2012, 10.1038/ngeo1638 (3) Konrad et al., 2018, 10.1038/s41467-018-03277-x (4) Finlayson et al., 2018, 10.1016/j.epsl.2018.08.020- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V13B..02K
- Keywords:
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- 1033 Intra-plate processes;
- GEOCHEMISTRY;
- 7208 Mantle;
- SEISMOLOGY;
- 8137 Hotspots;
- large igneous provinces;
- and flood basalt volcanism;
- TECTONOPHYSICS;
- 8416 Mid-oceanic ridge processes;
- VOLCANOLOGY