Melting of Refractory Mantle at 1middle dot5, 2 and 2middle dot5 GPa under Anhydrous and H2O-undersaturated Conditions: Implications for the Petrogenesis of High-Ca Boninites and the Influence of Subduction Components on Mantle Melting

High-K ankaramitic melt inclusions and lavas in the Upper Cretaceous Eastern Srednogorie continental arc, Bulgaria: Implications for the genesis of arc shoshonites

“…Although the lower temperatures of the olivine-spinel thermometer are, most probably, the result of diffusive re-equilibration, we cannot rule out the possibility that this difference is due to dissolved water. If the dissolved H 2 O content was~3 wt.% (see above), it would depress the liquidus temperatures by~110°C (Falloon and Danyushevsky, 2000), which is comparable to the observed difference of 70-100°C. This assumption is consistent with the fact the those olivine-liquid geothermometers resulted the lowest temperatures that are known to best reproduce experimental results for hydrous magmas (i.e.…”

Neoarchean siliceous high-Mg basalt (SHMB) from the Taishan granite–greenstone terrane, Eastern North China Craton: Petrogenesis and tectonic implications

“…Additionally, their particularly low TiO 2 and HFSE abundances, their locally high Al 2 O 3 /TiO 2 ratios (higher than primitive mantle values of ∼21) and marked depletion in Nd isotopic composition (ε Nd (t = 2.54) value up to 4.45), indicate that their source region is highly depleted and refractory peridotitic mantle that has likely experienced one or more episodes of basaltic melt extraction prior to remelting (e.g., Sun and Nesbitt, 1978;Cameron et al, 1983;Crawford et al, 1989). On the other hand, their siliceous, strong LILE and LREE enrichment and HFSE depletion may be ascribed to melting of metasomatically enriched lithospheric mantle (Weaver and Tarney, 1981;Fisk, 1986;Falloon and Danyushevsky, 2000;Smithies et al, 2004a). Hence, their petrogenesis is most likely comparable to that of typical Phanerozoic and Archean boninites (e.g., Crawford et al, 1989;Falloon and Danyushevsky, 2000;Smithies et al, 2004a), being especially similar to the Late Paleocene boninites from the Cape Vogel peninsula of Papua New Guinea (i.e., PNG boninites; König et al, 2010) and the Mesoarchean Whundo boninite-like rocks from the Pilbara Craton in northwestern Australia as shown in Fig.…”

“…On the other hand, their siliceous, strong LILE and LREE enrichment and HFSE depletion may be ascribed to melting of metasomatically enriched lithospheric mantle (Weaver and Tarney, 1981;Fisk, 1986;Falloon and Danyushevsky, 2000;Smithies et al, 2004a). Hence, their petrogenesis is most likely comparable to that of typical Phanerozoic and Archean boninites (e.g., Crawford et al, 1989;Falloon and Danyushevsky, 2000;Smithies et al, 2004a), being especially similar to the Late Paleocene boninites from the Cape Vogel peninsula of Papua New Guinea (i.e., PNG boninites; König et al, 2010) and the Mesoarchean Whundo boninite-like rocks from the Pilbara Craton in northwestern Australia as shown in Fig. 5a and b.…”

“…For the Taishan SHMBs, the enriched LREE patterns ((La/Yb) cn = 6.29-15.64) and fractionated HREE ((Gd/Yb) cn = 2.61-3.12) imply deep melting in equilibrium with residual garnet in the source (König et al, 2010), rather than a residue of amphibole which is generally invoked to interpret the U-type REE patterns and positive Zr anomalies in Phanerozoic boninites (e.g., Sun and Nesbitt, 1978;Hickey and Frey, 1982;Crawford et al, 1989;Falloon and Danyushevsky, 2000). In addition, the Zr depletion relative to Sm and Ti depletion relative to Eu also supports the above interpretation, which is likely related to the breakdown of amphibole at depth, similar to the features of the Adola and Tasmania boninites (Brown and Jenner, 1989;Crawford and Berry, 1992).…”

“…According to previous studies, the following tectonic settings can provide both the intense hydration and the elevated temperatures (up to 1350 • C) that are required to trigger partial melting of refractory mantle peridotite in order to generate boninitic rocks (Sun and Nesbitt, 1978;Beccaluva and Serri, 1988;Falloon and Danyushevsky, 2000): (1) initiation of a subduction zone along either a spreading center or a transfer fault (e.g., Falloon and Crawford, 1991;Ishikawa et al, 2002); (2) ridge subduction (e.g., Crawford et al, 1989;Piercey et al, 2001;Bourdon et al, 2003); (3) subduction of oceanic lithosphere beneath young hot oceanic lithosphere and back-arc basin openings (e.g., Coish et al, 1982;Tatsumi and Maruyama, 1989); (4) plume-island arc interaction (e.g., Danyushevsky et al, 1995;Kerrich et al, 1998;Boily and Dion, 2002;Falloon et al, 2008); and (5) extension of Pearce, 1983). Symbols and data as in Fig.…”