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Lithospheric mantle evolution beneath northeast Australia
New in situ analyses of Re–Os systematics in single grains of sulfides in Cainozoic basalt-borne spinel lherzolite xenoliths from the Chudleigh Province (Australian craton) and Atherton Province (Tasman Fold Belt) are reported. The sulfide data and previously reported U–Pb and Hf-isotope data for de...
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| Published in: | Lithos 2011-07, Vol.125 (1-2), p.405-422 |
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| Main Authors: | , , |
| Format: | Article |
| Language: | English |
| Subjects: | |
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| Online Access: | Get full text |
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| Summary: | New in situ analyses of Re–Os systematics in single grains of sulfides in Cainozoic basalt-borne spinel lherzolite xenoliths from the Chudleigh Province (Australian craton) and Atherton Province (Tasman Fold Belt) are reported. The sulfide data and previously reported U–Pb and Hf-isotope data for detrital zircons and zircons from granitoids (Murgulov et al., 2007; 2009) show correlations between mantle events and crustal magmatism in northeast Queensland, Australia. About half of the analysed sulfide grains have sub-chondritic 187Os/188Os (0.1130–0.1252) and 187Re/188Os (0.0214–0.2061), suggesting preservation of their isotopic signatures during subsequent infiltration of asthenospheric silicate melts/fluids. Collision and accretion processes have probably initiated a melt-extraction event followed by cratonic lithosphere stabilisation at ~2.2Ga (TMA model age). Metasomatism of the mantle lithosphere most likely involved infiltration of asthenospheric melts/fluids during lithospheric thinning and rifting beneath the Chudleigh Province at ~1.82Ga, 0.81Ga and 0.35Ga (TRD Rhenium-depletion model ages), beneath the Atherton Province at ~1.75Ga and 0.44Ga (TRD), and during suturing at ~1.23Ga (TRD), an event recorded beneath both provinces. In the Georgetown Inlier TRD model ages coincide with episodes of granitoid production and demonstrate a close temporal linkage between events in the cratonic lithospheric mantle and crust. However, such linkages cannot be demonstrated in the Tasman Fold Belt; no ~0.44Ga, 1.23Ga or 1.75Ga granites outcrop in this region, and the shallow part of the subjacent lithospheric mantle (~27km depth) experienced a younger (~0.44Ga) metasomatic event not observed in the deeper lithosphere (~49km depth, ~1.75Ga). The younger event may be associated with the reactivation of ancient lithospheric sutures during mantle upwelling and back-arc rifting. The older events may imply that the edge of the cratonic lithospheric mantle root, metasomatised at ~1.75Ga and 1.23Ga, was rifted during a younger event (~0.44Ga?). Its scattered fragments have been embedded at greater depth within the lithospheric mantle beneath the Atherton Province following collision, accretion and lithosphere suturing.
► Melt-extraction and lithosphere stabilisation in Queensland at ~ 2.20Ga. ► Metasomatic events beneath the craton at ~ 1.82Ga, 1.23Ga, 0.81Ga and 0.35Ga. ► Linkage between events in the lithospheric mantle and crust of the Australian craton. ► 1.75 and 0. |
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| ISSN: | 0024-4937 1872-6143 |
| DOI: | 10.1016/j.lithos.2011.03.002 |