Journal of Geography (Chigaku Zasshi)
Online ISSN : 1884-0884
Print ISSN : 0022-135X
The 100s: Significant Exposures of the World (No.11)
Ultrapotassic Magma from the Deep Mantle, Leucite Hills Lamproite, Wyoming USA
Akira ISHIKAWAKenji KAWAI
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2015 Volume 124 Issue 3 Pages 515-523

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Abstract

 The Leucite Hills province is an isolated volcanic field of 14 lava-capped mesas and buttes, creating an impressive landscape in southwestern Wyoming. The 3.0-0.89 Ma lavas form exotic rocks described as lamproites, which are regarded as the most potassic (< 13wt% K2O) and incompatible trace element-rich primitive magmas generated in the deep Earth. The radiogenic isotope signatures of Leucite Hills lamproites are well beyond the range of any known oceanic basalts, suggesting that the magma originated from ancient, volatile-rich anomalous mantle, recently reactivated by the convective removal of metasomatised lithosphere present at the margin of the Archean Wyoming Craton.

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© 2015 Tokyo Geographical Society
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