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Paleomagnetism of igneous rocks from the Shatsky Rise: Implications for paleolatitude and oceanic plateau volcanism

By
William W. Sager
William W. Sager
Department of Oceanography, Texas A&M University, College Station, Texas 77843, USA
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Margaret Pueringer
Margaret Pueringer
Department of Geology & Geophysics, Texas A&M University, College Station, Texas 77843, USA
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Claire Carvallo
Claire Carvallo
Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités–Université Pierre-et-Marie-Curie (UPMC, Université Paris 06), Unités Mixtes de Recherche Centre National de la Recherche Scientifique (UMR CNRS) 7590, Muséum National d'Histoire Naturelle, Institut de Recherche (IRD) UMR 206, 4 Place Jussieu, F-75005 Paris, France
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Masahiro Ooga
Masahiro Ooga
Department of Environmental System Science, Doshisha University, 1-3 Tatara Miyakodani, Kyo-Tanabe City, Kyoto 610-0321, Japan
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Bernard Housen
Bernard Housen
Geology Department, Western Washington University, Bellingham, Washington 98225, USA
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Masako Tominaga
Masako Tominaga
Department of Geological Sciences, Michigan State University, East Lansing, Michigan 48824, USA
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Published:
May 01, 2015

The eruptive history of the Shatsky Rise, a large oceanic plateau in the northwestern Pacific Ocean, is poorly understood. Although it has been concluded that the Shatsky Rise volcanic edifices erupted rapidly, there are few solid chronological data to support this conclusion. Similarly, the Shatsky Rise is thought to have formed near the equator, but paleolatitude data from the plateau are few, making it difficult to assess its plate tectonic drift with time. To understand the formation history of this oceanic plateau, paleomagnetic measurements were conducted on a total of 362 basaltic lava samples cored from the Shatsky Rise at 4 sites (U1346, U1347, U1349, and U1350) during Integrated Ocean Drilling Program Expedition 324. Examining changes in paleomagnetic inclinations, we gain a better understanding of eruptive rates by comparison of observed shifts in inclination with expected paleosecular variation. At three sites (U1346, U1347, and U1349) little change in paleomagnetic directions was observed, implying that the cored sections were mostly erupted rapidly over periods of <~100–200 yr. Only Site U1350 displayed directional changes consistent with significant paleosecular variation, implying emplacement over a period of ~1000 yr. The paleomagnetic data are consistent with the idea that the Shatsky Rise igneous sections were mostly emplaced rapidly, but there were some time gaps and some fl ank locations built up more slowly. Because paleosecular variation was inadequately sampled at all the Shatsky Rise sites, paleolatitudes have large uncertainties, and because of the equatorial location, magnetic polarity is also uncertain. All sites yield low paleolatitudes and indicate that the Shatsky Rise stayed near the equator during its formation. Given that the locus of magmatism moved northward relative to the Pacific plate while staying near the equator, the Pacific plate must have drifted southward relative to the spin axis during the emplacement of the plateau.

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GSA Special Papers

The Origin, Evolution, and Environmental Impact of Oceanic Large Igneous Provinces

Clive R. Neal
Clive R. Neal
Department of Civil & Environmental Engineering & Earth Sciences, 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, Indiana 46556, USA
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William W. Sager
William W. Sager
Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas 77204-5007, USA
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Takashi Sano
Takashi Sano
Department of Geology and Paleontology, National Museum of Nature and Science, Tsukuba 305-0005, Japan
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Elisabetta Erba
Elisabetta Erba
Department of Earth Sciences, Università degli Studi di Milano, 20133 Milan, Italy
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Geological Society of America
Volume
511
ISBN print:
9780813725116
Publication date:
May 01, 2015

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