Contrasting Sources For Upper and Lower Continental Crust: the Greenstone Connection

Episodic crustal growth in the southern segment of the Trans-North China Orogen across the Archean-Proterozoic boundary

“…Therefore, the Dengfeng and Taihua TTGs at 2.30-2.57 Ga are all partial melts of thickened lower crust, which might have formed through orogeny (e.g., Burg and Ford, 1997), repeated underplating (e.g., Furlong and Fountain, 1986;Haschke et al, 2002), intraoceanic plate stacking (De Wit, 1998), and/or oceanic plateau accretion (e.g., De Wit et al, 1992;Desrochers et al, 1993;Condie, 1997). The last two processes would produce dominantly juvenile crust, which contradicts the abundant inherited zircons and negative whole rock ε Nd (t) and zircon ε Hf (t) values recorded by the Dengfeng and Xiaoqinling TTGs.…”

Geochronology and petrogenesis of gray gneisses from the Taihua Complex at Xiong'er in the southern segment of the Trans-North China Orogen: Implications for tectonic transformation in the Early Paleoproterozoic

“…This might have resulted from several processes, such as orogenesis (e.g., Burg and Ford, 1997), repeated underplating (e.g., Furlong and Fountain, 1986;Haschke et al, 2002), intra-oceanic plate stacking (De Wit, 1998) and/or oceanic plateau accretion (e.g., Condie, 1997;De Wit et al, 1992;Desrochers et al, 1993). The last two processes are not applicable for genesis of the Taihua TTGs at Xiong'er because inherited zircons (2286 ± 7 Ma to 3352 ± 14 Ma), whole rock ε Nd (t) and zircon ε Hf (t) values all suggest the participation of pre-existing crustal materials.…”

Geochronology and geochemistry of 2.5 to 2.4Ga granitic plutons from the southern margin of the North China Craton: Implications for a tectonic transition from arc to post-collisional setting

“…The generation of Archean crust is attributed to mantle plume (e.g., Abbott, 1996;Condie, 1997), plate subduction (e.g., Condie, 1994;Smithies et al, 2007), or both (e.g., Hollings and Wyman, 1999). TTG assemblage is commonly considered to be a product of partial melting of subducted slab, oceanic plateau, root zone of volcanic arcs (e.g., Martin and Moyen, 2002;Martin et al, 2005;Condie, 2005) or hydrous thickened basaltic crust at the lowest crust (e.g., Smithies, 2000Smithies, , 2002Condie, 2005).…”