238U-230Th disequilibria, magma petrogenesis, and flux rates beneath the depleted Tonga-Kermadec island arc

Online Access: Get full text
doi: 10.1016/S0016-7037(97)00281-0
Author(s): Turner, Simon; Hawkesworth, Chris; Rogers, Nick; Bartlett, Jessica; Worthington, Tim; Hergt, Janet; Pearce, Julian; Smith, Ian
Author Affiliation(s): Primary:
Open University, Department of Earth Sciences, Milton Keynes, United Kingdom
Other:
University of Auckland, New Zealand
University of Melbourne, Australia
University of Durham, United Kingdom
Volume Title: Geochimica et Cosmochimica Acta
Source: Geochimica et Cosmochimica Acta, 61(22), p.4855-4884. Publisher: Pergamon, Oxford, International. ISSN: 0016-7037 CODEN: GCACAK
Note: In English. 106 refs.; illus., incl. 5 tables, sketch maps
Summary: Analyses are presented of 58 samples of lavas sampling the length and compositional range of this arc, including samples from the Ngatoro Ridge, the back-arc island of Niuafo'ou and xenoliths from Raoul. The resulting data include major oxides, minor and trace elements, Sr, Nd and Pb-U isotopes. Nineteen sediment samples from DSDP Site 204 were additionally analysed for major, trace elements and Sr, Nd and Pb isotopes. Most of the lavas analysed are tholeiites with MgO 4-8%. Within-island and overall major element trends such as negative correlations between MgO and SiO2, Fe2O3, CaO and Al2O3 indicate fractionation of phenocrysts olivine, pyroxene and plagioclase. Components for the petrogenesis of the lavas include: 1) the mantle wedge, 2) with elevated 207Pb/204Pb, 3) with high 206Pb/204Pb, Ta/Nd and low 143Nd/144Nd (N Tonga islands of Tafahi and Niuatoputapu) and 4) a fluid enriched in Rb, Ba, U, K, Pb and Sr relative to Th, Zr and REE. The mantle wedge is isotopically similar to the source of the Law Basin lavas; 2) is average pelagic sediment on the subducting Pacific plate; 3) is volcaniclastics from the Louisville Ridge, and 4) derives from dehydration of subducting altered.
Year of Publication: 1997
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 02 Geochemistry; 05 Petrology, Igneous and Metamorphic; Actinides; Alkaline earth metals; Andesites; Basalts; Chemical ratios; DSDP Site 204; DSDP Site 595; DSDP Site 596; Deep Sea Drilling Project; Geochemistry; IPOD; Igneous rocks; Inclusions; Island arcs; Isotope ratios; Isotopes; Kermadec Islands; Lava; Lead; Leg 21; Leg 91; Lithogeochemistry; Magmas; Major elements; Mass balance; Metals; Nd-144/Nd-143; Neodymium; Oceania; Pacific Ocean; Pb-206/Pb-204; Polynesia; Radioactive isotopes; Rare earths; Sr-87/Sr-86; Stable isotopes; Strontium; Th-232/Th-230; Tholeiitic basalt; Thorium; Tonga; Trace elements; U-238/Th-232; Uranium; Uranium disequilibrium; Volcanic rocks; West Pacific Ocean Islands; Xenoliths
Coordinates: S245716 S245716 W1740641 W1740641
S234921 S234921 W1653151 W1653151
S235113 S235111 W1653916 W1653917
Record ID: 1998013465
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom