Identification of a Hawaiian-Emperor Style Bend in the Tuvalu Segment of the Rurutu Hotspot
Abstract
Absolute plate motion (APM) models continue to improve with better characterization of drift of the two primary hotspots: Hawaii and Louisville. While APM models are more reliable from 50 Ma to modern times, uncertainty is introduced prior to 50 Ma due to hotspot track mismatch, uncertain location of the Louisville hotspot, and inter-hotspot drift as deduced from paleolatitude data [1,2]. Hawaiian hotspot drift contributed to a sharp 50 Ma Hawaiian-Emperor Bend (HEB) not reflected by the Louisville track. Adding a third HEB to the known long-lived hotspot tracks allows evaluation of APM uncertainty and hotspot drift. We present Pb-Sr-Nd-Hf isotopes and 40Ar/39Ar ages that complement existing Rurutu data [3], and for the first time trace the hotspot through its HEB back to 100 Ma. Our results reveal that the Tuvalu chain and some western Samoa seamounts define an age-progressive 63-42 Ma segment of the Rurutu track. The segment displays various mixtures between extreme endmember HIMU (206Pb/204Pb ≥ 20) and compositionally common FOZO [4,5] typical of Rurutu volcanism [3,6]. Other compositions also occur, differing in age and origin. In addition to the Rurutu-related seamounts, three seamounts were also sampled that have depleted mid-ocean ridge basalt compositions and ages that coincide with the opening of the underlying ocean basin. While distinct from the Rurutu hotspot, Samoan volcanoes overlapping 50-42 Ma Rurutu seamounts prevent straightforward identification of the HEB. Using age, composition, and location data, we project the Rurutu track with a moving hotspot APM model [7] from each age-dated seamount, defining the likeliest location with a cluster of projected HEBs. We find the Rurutu HEB occurs near the intersection of Tuvalu and western Samoa, providing a key constraint required to evaluate APM and inter-hotspot drift. 1. Koppers et al., (2012) doi:10.1038/ngeo1638 2. Tarduno et al., (2003) doi:10.1126/science.1086442 3. Konter et al., (2008) doi:10.1016/j.epsl.2008.08.023 4. Hart et al. (1992) doi:10.1126/science.256.5056.517 5. Hauri & Hart (1994) doi:10.1029/94JB01257 6. Chauvel et al., (1997) doi:10.1016/S0009-2541(97)00029-6 7. Doubrovine et al., (2012) doi:10.1029/2011JB009072
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMDI52A..05F
- Keywords:
-
- 1025 Composition of the mantle;
- GEOCHEMISTRYDE: 3924 High-pressure behavior;
- MINERAL PHYSICSDE: 7208 Mantle;
- SEISMOLOGY