FN Archimer Export Format PT J TI From intracratonic extension to mature spreading in back arc basins: Examples from the Okinawa, Lau, North Fiji basins OT De l'extension intracratonique a l'ouverture oceanique clans les bassins arIiere Arc : exemples des bassins cl'Okinawa, de Lau et Nord Fidjien BT AF AUZENDE, Jean-Marie BOESPFLUG, Xavier BOUGAULT, Henri DOSSO, Laure FOUCHER, Jean-Paul JORON, Jean-Louis RUELLAN, Etienne SIBUET, Jean-Claude AS 1:;2:;3:;4:;5:;6:;7:;8:; FF 1:;2:;3:;4:;5:;6:;7:;8:; IF 0.662 TC 0 UR https://archimer.ifremer.fr/doc/00119/23058/20893.pdf LA English DT Article DE ;Ouest Pacifique;Bassins arriere arc;Structure;Accretion;geochimie;West Pacific;Back arc basins;Structure;Accretion;Geochemistry AB Three cruises (POP 1, SEAPSO 3 and SEAPSO 4) carried out during the "Tour du Monde" of the R.V. Jean Charcot allow us to obtain new structural and geochemical data for the Okinawa, North Fiji and Lau basins. Taken together, the structural and geochemical data illustrate a difference in evolution stages of these sites. The less evolved stage is represented by the Okinawa basin, where accretion is evidenced only by volcanic intrusion into a thinned continental crust. The most evolved stage is illustrated in the North Fiji basin, where the present-day accretion can be directly compmĀ·ed to the East Pacific Ridge. The Lau basin displays an intem1ediate stage with a complex system of accretionary ridges. This difference in the evolution stage is translated in the nature and geochemistry of the rocks : in the Okinawa trough they are basalts, andesites and dacites enriched in hydromagmaphile m1d rare earth elements. In the Lau basin they are typical N. Morb basalts in the central pmt of the basin and inteimediate composition between Morb and m1desites on Valu Fa ridge. Lastly, the North Fiji basin axis provides only typical Morb basalts. PY 1990 SO Oceanologica Acta SN 0399-1784 PU Elsevier VL Spec. 10 BP 153 EP 162 ID 23058 ER EF