Major zircon megacryst suites of the Indo-Pacific lithospheric margin (ZIP) and their petrogenetic and regional implications

Abstract : Zircon megacrysts (± gem corundum) appear in basalt fields of Indo-Pacific origin over a 12,000 km zone (ZIP) along West Pacific continental margins. Age-dating, trace element, oxygen and hafnium isotope studies on representative zircons (East Australia–Asia) indicate diverse magmatic sources. The U–Pb (249 to 1 Ma) and zircon fission track (ZFT) ages (65 to 1 Ma) suggest thermal annealing during later basalt transport, with < 1 to 203 Ma gaps between the U–Pb and ZFT ages. Magmatic growth zonation and Zr/Hf ratios (0.01–0.02) suggest alkaline magmatic sources, while Ti—in—zircon thermometry suggests that most zircons crystallized within ranges between 550 and 830 °C. Chondrite-normalised multi-element plots show variable enrichment patterns, mostly without marked Eu depletion, indicating little plagioclase fractionation in source melts. Key elements and ratios matched against zircons from magmatic rocks suggest a range of ultramafic to felsic source melts. Zircon O-isotope ratios (δ18O in the range 4 to 11‰) and initial Hf isotope ratios (εHf in the range +2 to +14) encompass ranges for both mantle and crustal melts. Calculated Depleted Mantle (TDM 0.03–0.56 Ga) and Crustal Residence (0.20–1.02 Ga) model ages suggest several mantle events, continental break-ups (Rodinia and Gondwana) and convergent margin collisions left imprints in the zircon source melts. East Australian ZIP sites reflect prolonged intraplate magmatism (~85 Ma), often during times of fast-migrating lithosphere. In contrast, East Asian-Russian ZIP sites reflect later basaltic magmatism (<40 Ma), often linked to episodes of back-arc rifting and spreading, slow-migrating lithosphere and slab subduction.
Document type :
Journal articles
Complete list of metadatas

https://hal.univ-lorraine.fr/hal-01770218
Contributor : Crpg Ul <>
Submitted on : Wednesday, April 18, 2018 - 4:48:40 PM
Last modification on : Tuesday, July 9, 2019 - 4:50:30 PM

Identifiers

Collections

Citation

Lin Sutherland, Ian Graham, Gregory Yaxley, Richard Armstrong, Gaston Giuliani, et al.. Major zircon megacryst suites of the Indo-Pacific lithospheric margin (ZIP) and their petrogenetic and regional implications. Mineralogy and Petrology, Springer Verlag, 2016, 110 (2-3), pp.399 - 420. ⟨10.1007/s00710-015-0421-3⟩. ⟨hal-01770218⟩

Share

Metrics

Record views

74