Implications of a nonlinear 40Ar/39Ar age progression along the Louisville seamount trail for models of fixed and moving hot spots

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doi: 10.1029/2003GC000671
Author(s): Koppers, Anthony A. P.; Duncan, Robert A.; Steinberger, Bernhard
Author Affiliation(s): Primary:
Scripps Institution of Oceanography, Institute of Geophysics and Planetary Physics, La Jolla, CA, United States
Oregon State University, United States
Japan Agency for Marine-Earth Science and Technology, Japan
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 5(6), 22p. Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. Accessed on Sept. 10, 2004. 42 refs.; illus., incl. 4 tables, sketch map
Summary: The Louisville seamount trail has been recognized as one of the key examples of hot spot volcanism, comparable to the classic volcanic Hawaiian-Emperor lineaments. The published total fusion 40Ar/39Ar data of Watts et al. [1988] showed an astonishing linear age progression, firmly establishing Louisville as a fixed hot spot in the South Pacific mantle. We report new 40Ar/39Ar ages based on high-resolution incremental heating 40Ar/39Ar dating for the same group of samples, showing a marked increase in both precision and accuracy. One of the key findings in our reexamination is that the age progression is not linear after all. The new data show a significantly decreased "apparent" plate velocity for the Louisville seamount trail older than 62 Ma but confirm the linear trend between 47 Ma and the present day (although based on only three samples over 2150 km). The most recent volcanic activity in the Louisville seamount trail has now been dated at 1.11±0.04 Ma for the most southeastern seamount located at 50°26'S and 139°09'W. These results indicate that the Louisville age progression should be interpreted on the basis of both plate and hot spot motion. In this paper we examine our new results in conjunction with the numerical mantle flow models of Steinberger et al. [2004] that also predict marked deviations from simple linear age progressions. With these models we can achieve a good fit to the geometry of both the Hawaiian and Louisville seamount trails and their age progressions as well as the ∼15° paleolatitudinal shift observed by Tarduno et al. [2003] for the Hawaiian hot spot between 80 and 47 Ma. If the model is restricted to Pacific hot spots only, we can improve the fit to the nonlinear age trend for the Louisville seamount trail by allowing an additional rotation change of the Pacific plate around 62 Ma and by decreasing the initiation age of the Louisville plume from 120 to 90 Ma. This improved model features a significant eastward hot spot motion of ∼5° between 80 and 30 Ma for the Louisville hot spot, which is quite dissimilar to the southward motion of the Hawaiian hot spot during the same time interval, followed by a minor ∼2° latitudinal shift over the last 30 Myr. If hot spot tracks are considered globally, the age trend observed for the oldest part of the Louisville seamount trail does not entirely follow the numerical model predictions. This may indicate some remaining inaccuracies in the global plate circuit, but it may also indicate that the Louisville hot spot experienced a motion somewhat different than in the numerical model: faster in the interval between 62 and 47 Ma but slower before that.
Year of Publication: 2004
Research Program: ODP Ocean Drilling Program
Key Words: 03 Geochronology; Absolute age; Alteration; Ar/Ar; Cenozoic; Cretaceous; Dates; East Pacific; Emperor Seamounts; Hot spots; Leg 197; Lineaments; Louisville Ridge; Mantle; Mesozoic; North Pacific; Northwest Pacific; Ocean Drilling Program; Pacific Ocean; Pacific Plate; Paleogene; Plate tectonics; South Pacific; Southeast Pacific; Tectonics; Tertiary; Upper Cretaceous; West Pacific
Coordinates: S450000 S250000 W1500000 W1800000
Record ID: 2004076588
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