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Paleomagnetic results from Tertiary volcanic strata and intrusions, Absaroka Volcanic Supergroup, Yellowstone National Park and vicinity: Contributions to the North American apparent polar wander path

Tectonophysics

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DOI: 10.1016/j.tecto.2009.12.025

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Abstract

We report paleomagnetic and rock magnetic data from volcanic, volcaniclastic, and intrusive rocks of the 55-44Ma Absaroka Volcanic Supergroup (AVS) exposed along the northeastern margin of Yellowstone National Park and adjacent areas. Demagnetization behavior and rock magnetic experiments indicate that the remanence in most samples is carried by low-Ti titanomagnetite, although high-coercivity phases are present in oxidized basalt flows. Paleomagnetic demagnetization and rock magnetic characteristics, the presence of normal and reverse polarity sites, consistency with previous results, and positive conglomerate tests suggest that the observed remanences are primary thermoremanent magnetizations of Eocene age (c. 50Ma). An in situ grand-mean for 22 individual site- or cooling-unit means from this study that yield acceptable data combined with published data from Independence volcano yields a declination of 347.6?? and inclination of 59.2?? (k=21.8, ??95=6.8??) and a positive reversal test. Averaging 21 virtual geomagnetic poles (VGPs) that are well-grouped yields a mean at 137.1??E, 82.5??N (K=17.6, A95=7.8??), similar to results previously obtained from published studies from the AVS. Combining the VGPs from our study with published data yields a combined AVS pole at 146.3??E, 83.1??N (K=13.5, A95=6.2??, N=42 VGPs). Both poles are indistinguishable from c. 50Ma cratonic and synthetic reference poles for North America, and demonstrate the relative stability of this part of the Cordillera with respect to the craton. ?? 2009 Elsevier B.V.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Paleomagnetic results from Tertiary volcanic strata and intrusions, Absaroka Volcanic Supergroup, Yellowstone National Park and vicinity: Contributions to the North American apparent polar wander path
Series title:
Tectonophysics
DOI:
10.1016/j.tecto.2009.12.025
Volume
485
Issue:
1-4
Year Published:
2010
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
245
Last page:
259
Number of Pages:
15