Botanical and Geological Significance of Potassium-Argon Dates from the Juan Fernández Islands
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- Tod F. Stuessy
- Department of Botany, Ohio State University, Columbus 43210
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- K. A. Foland
- Department of Geology and Mineralogy, Ohio State University
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- John F. Sutter
- Department of Geology and Mineralogy, Ohio State University
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- Roger W. Sanders
- Department of Botany, Ohio State University
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- Mario Silva O.
- Departamento de Botánica, Universidad de Concepción, Concepción, Chile
抄録
<jats:p> Potassium-argon dating of five basalts from the three main islands of the Juan Fernández (or Robinson Crusoe) Islands of Chile in the southeastern Pacific gives ages of 1.01 ± 0.12 and 2.44 ± 0.14 million years for Masafuera, 3.79 ± 0.20 and 4.23 ± 0.16 for Masatierra, and 5.8 ± 2.1 for Santa Clara. These ages are much younger than that of the underlying oceanic plate and are consistent with the origin of the island-seamount chain from a mantle hot spot beneath the eastward moving Nazca plate. The young age for the archipelago suggests that speciation within endemic genera has occurred within the past 4 to 5 million years. Endemic genera of apparently more ancient origins, such as <jats:italic>Lactoris</jats:italic> and <jats:italic>Thyrsopteris</jats:italic> , have apparently dispersed to the islands and survive refugially. </jats:p>
収録刊行物
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- Science
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Science 225 (4657), 49-51, 1984-07-06
American Association for the Advancement of Science (AAAS)
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キーワード
詳細情報 詳細情報について
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- CRID
- 1361981469802701312
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- ISSN
- 10959203
- 00368075
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- データソース種別
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- Crossref