Formation of mafic magmas through lower crustal AFC processes — An example from the Jinan gabbroic intrusion in the North China Block

Continental flood basalts derived from the hydrous mantle transition zone

“…Typical ion intensities of 2-4 Â 10 6 counts per second obtained on the 18 O peak yielded an internal 2s uncertainty of better than ± 0.2%. Three unknown and two standard d 18 [63][64][65] . However, olivine with Fo number o65 has been proven to show about 0.6 permil bias IMF with San Carlos olivine as the standard 65 .…”

“…Three unknown and two standard d 18 [63][64][65] . However, olivine with Fo number o65 has been proven to show about 0.6 permil bias IMF with San Carlos olivine as the standard 65 . Considering the unknown olivine grains have Fo number ranging from 60 to 91, we selected only grains with Fo 470 for oxygen isotope analysis.…”

Two types of the crust-mantle interaction in continental subduction zones

“…The rock types of mafic igneous rocks are gabbro, gabbroic diorite, mafic dyke/vein (dolerite, lamprophyre) and basalt. Geochronological studies (especially in-situ zircon U-Pb dating) have revealed that the postcollisional mafic igneous rocks in the Dabie orogen formed at 113 to 132 Ma (Jahn et al, 1999;Huang et al, 2007;Zhao and Zheng, 2009;Dai et al, 2011Dai et al, , 2012Xu et al, 2012b); the syn-exhumation mafic igneous rocks in the Sulu orogen formed at 201 to 213 Ma (Yang et al, 2005;Zhao et al, 2012), and the postcollisional mafic igneous rocks there formed at 111 to 129 Ma (Zhang et al, 2002, 2012; Xu et al, 2004;Gao et al, 2008;Yang et al, 2008;Zhao and Zheng, 2009;Guo et al, 2014); the mafic igneous rocks in SE North China mainly formed at 113 to 136 Ma (Yang et al, 2012a(Yang et al, , 2012b(Yang et al, , 2012cGuo et al, 2013a). The in-situ zircon U-Pb dating also indicates that some of the mafic igneous rocks in the Dabie orogen contain residual zircon cores with middle Neoproterozoic and Triassic ages (Dai et al, 2011.…”

“…They show variable zircon O isotope compositions with δ 18 O values of 2.0‰ to 7.3‰ (Figure 5(a)), most of them are different from those of (5.3±0.3)‰ for the normal mantle zircon (Valley et al, 1998). Olivine also has δ 18 O values different from those of the normal mantle olivine (Guo et al, 2013a(Guo et al, , 2013b.…”

Hf–Nd–O isotopic evidence for melting of recycled sediments beneath the Sulu Orogen, North China

“…Detailed description of the analytical procedure was reported in Li et al (2010) and Guo et al (2013a). During analysis, the Penglai and 91500 zircon standards respectively yield δ 18 O = 5.30 ± 0.11‰ (n = 29) and δ 18 O = 9.92 ± 0.29‰ (n = 20).…”