Petrology of Aitutaki, Cook Islands (Note)
1978; Taylor & Francis; Volume: 21; Issue: 6 Linguagem: Inglês
10.1080/00288306.1978.10425205
ISSN1175-8791
Autores Tópico(s)Geology and Paleoclimatology Research
ResumoAbstract The Pleistocene lavas and palagonite tuffs of Aitutaki form a nephelinic suite dominated by olivine nephelinite with lesser amounts of basanite. In age, composition, and occurrence, the volcanic rocks of Aitutaki are similar to the Honolulu Group on Oahu in the Hawaiian Islands. Major and trace element analyses of six olivine nephelinites and two basanites are reported. These show that olivine nephelinite is the more fractionated lava, but cannot be derived from a parental basanite magma because neither high-pressure nor low-pressure mineral fractionation schemes can account for the observed chemical differences. The olivine nephelinite may result from a smaller degree of partial fusion at greater depth in the upper mantle than the basanite. Both melts were probably hydrous, but olivine nephelinite may also have contained CO2
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