https://nova.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:50843 1200°C. Silicon and Al contents and Mg# of serpentinized spinel harzburgite, as well as heavy rare earth element modeling results, suggest a high-degree of melt extraction of 20–30% in the garnet stability field and in an anhydrous environment, probably in ocean island or oceanic plateau environments. The samples in this study have HSE concentrations interpreted to have resulted from post-melting processes rather than a melt extraction feature, indicating that their Re–Os model ages need to be interpreted with caution. Nevertheless, the melt depletion ages obtained from the Woodsreef and Port Macquaries samples range between 1.4 and 1.1 Ga, consistent with previous studies on other Pacific-rim ophiolitic rocks. We argue that these ages might be related to a major depletion event during the transition between supercontinents Nuna and Rodinia. Such depletion events affected a large proportion of this section of the mantle before the incorporation of the peridotites into the oceanic lithosphere in the Paleo-Pacific associated with rapid ascent of mantle plumes. This interpretation is consistent with the occurrence of accreted volcanic islands in the Weraerai ophiolite mélange, as shown by the OIB chemical signatures of some of the mafic rocks, and their association with shallow water limestones that formed in near-equatorial latitudes. The proposed c. 530–510 Ma Paleo-Pacific Ocean mantle plume event coincides with a global peak of oceanic mantle plume events that may record the legacy of a circum-Rodinia subduction girdle driving antipodal mantle superplume episodes.]]> Wed 09 Aug 2023 09:17:40 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:7115 Sat 24 Mar 2018 08:34:11 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26031 1000). In all dynamic regimes d is proportional to Q and inversely proportional to the density difference between the fluids. Significant mobilization and entrainment of sulfide liquid, as indicated by predicted draw-up cones with d between 1 and 10 m, can occur under inertial conditions at high (Q ∼ 1–1000 m³s⁻¹) magma volumetric flow rates that are plausible for mid- to upper-crustal magma chambers. Although entrainment can potentially generate sulfide-rich magma pulses, it probably represents only an initial step in the mobilization of sulfide liquid and the genesis of magmatic sulfide deposits. Entrained sulfide liquids must be transported upwards and/or laterally from their site of mobilization towards their site of deposition, which may occur as coherent masses or as droplets depending on the dynamics of the system. Although entrainment may be viable at the scale of sills, dykes, chonoliths and lava flows, it may not be significant in scenarios where significant (>100 m) thicknesses of molten mafic magma must be expelled prior to reaching 1–10 m scale critical draw-up heights; in such scenarios gravitational backflow of sulfide may be a more viable mechanism for producing economic concentrations of Ni–Cu sulfide mineralization.]]> Sat 24 Mar 2018 07:26:28 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:3436 Sat 24 Mar 2018 07:20:26 AEDT ]]>