C. Honthaas et al., OCCURRENCE OF TRACHYTES IN THE SUBSTRATUM OF FANGATAUFA ATOLL, GAMBIER LINEAR-CHAIN, FRENCH-POLYNESIA, Comptes rendus de l'Academie des sciences. Serie II. Mecanique, physique, chimie, astronomie, 320(4), 1995, pp. 257-263
Alkaline trachytes containing sodic plagioclase, sanidine, phlogopite,
zircon and apatite phenocrysts are described from the volcanic substr
atum of Fangataufa atoll, which was previously considered as exclusive
ly basaltic or hawaiitic. They occur as very altered dykes intruding s
ubmarine alkali basalt lava flows beneath the lagoon (Mitre 3 drill ho
le). They bring evidence of the occurrence of crystal fractionation pr
ocesses leading from alkali basalts to trachytic residual liquids, in
a probably short-lived magma chamber.