Guandishan Granitoids of the Paleoproterozoic Lüliang Metamorphic Complex in the Trans‐North China Orogen: SHRIMP Zircon Ages, Petrogenesis and Tectonic Implications

Abstract

The Paleoproterozoic Lüliang Metamorphic Complex (PLMC) is situated in the middle segment of the western margin of the Trans‐North China Orogen (TNCO), North China Craton (NCC). As the most important lithological assemblages in the southern part of the PLMC, Guandishan granitoids consist of early gneissic tonalities, granodiorites and gneissic monzogranites, and younger gneissic to massive monzogranites. Petrochemical features reveal that the early gneissic tonalities and granodiorites belong to the medium‐K calc‐alkaline series; the early gneissic monzogranites are transitional from high‐K calc‐alkaline to the shoshonite series; the younger gneissic to massive monzogranites belong to the high‐k calc‐alkaline series, and all rocks are characterized by right‐declined REE patterns and negative Nb, Ta, Sr, P, and Ti anomalies in the primitive mantle normalized spidergrams. SHRIMP zircon U–Pb isotopic dating reveals that the early gneissic tonalities and granodiorites formed at ∼2.17 Ga, the early gneissic monzogranites at ∼2.06 Ga, and the younger gneissic to massive monzogranites at ∼1.84 Ga. Sm–Nd isotopic data show that the early gneissic tonalities and granodiorites have ɛNd(t) values of +0.48 to –3.19 with Nd‐depleted mantle model ages (TDM) of 2.76–2.47 Ga, and early gneissic monzogranites have ɛNd(t) values of –0.53 to –2.51 with TDM of 2.61–2.43 Ga, and the younger gneissic monzogranites have ɛNd(t) values of –6.41 to –2.78 with a TDM of 2.69–2.52 Ga. These geochemical and isotopic data indicate that the early gneissic tonalities, granodiorites, and monzogranites were derived from the partial melting of metamorphosed basaltic and pelitic rocks, respectively, in a continental arc setting. The younger gneissic to massive monzogranites were derived by partial melting of metamorphosed greywackes within the continental crust. Combined with previously regional data, we suggest that the Paleoproterozoic granitoid magmatism in the Guandishan granitoids of the PLMC may provide the best geological signature for the complete spectrum of Paleoproterozoic geodynamic processes in the Trans‐North China Orogen from oceanic subduction, through collisional orogenesis, to post‐orogenic extension and uplift.

Late Permian–Triassic siliciclastic provenance, palaeogeography, and crustal growth of the Songpan terrane, eastern Tibetan Plateau: evidence from U–Pb ages, trace elements, and Hf isotopes of detrital zircons

“…Dongling gneiss: Xing et al 1993; Kongling high-grade terrane: Zheng et al 2006;references therein), much similar to the metamorphism in Trans-North China orogen (1887-1785 Ma), as revealed by broad isotopic studies (e.g. Trap et al 2007;Liu et al 2009b;Zhao and Zhai 2013;references therein). Therefore, the upper Permian sandstones yield age probability density functions consistent with the Qinling, Qilian, and Kunlun orogens along the southern margin of the North China Craton (Figure 12a).…”

Archean-Paleoproterozoic crustal evolution of the Ordos Block in the North China Craton: Constraints from zircon U–Pb geochronology and Hf isotopes for gneissic granitoids of the basement

“…Lithological studies display that most 2.2-2.0 Ga granitiods have medium-to coarse-grained textures and were more or less deformed. Such as granitoids are also widely recognized in the Wutai-Lüliang areas of the middle TNCO (Zhao et al, 2002(Zhao et al, , 2007(Zhao et al, , 2008bWilde et al, 2005;Trap et al, 2008;Liu et al, 2009cGeng et al, 2006b). Their geochemical studies revealed that these granitoids formed in a tectonic setting related to a continental margin/island arc (Liu et al, 2002Zhao and Zhai, 2013 and references cited therein) or in an extensional setting related to back-arc basin rifting (Du et al, , 2013, and then subjected two metamorphic events at ∼1.95 Ga and ∼1.85 Ga, respectively (Zhao and Zhai, 2013;Wei et al, 2014 and references cited therein).…”

Genesis of the Hengling magmatic belt in the North China Craton: Implications for Paleoproterozoic tectonics

“…Some of these granitic rocks are deformed with gneissic schistosity conformable with that of their host rocks (e.g., Mafeng monzogranites, Li and Zhao, 2007; tonalites in the Jiehekou Group/Complex, Zhao et al, 2008b); whereas others are largely undeformed (e.g., Tonghua A-type granites, Lu et al, 2004b; and Lingyunkou A-type granites, Zhao et al, 2011). Granodiorites and tonalites are mostly in the center of the NCC (Geng et al, 2000;Kröner et al, 2005;Liu et al, 2009b;Wang et al, 2010c;Wilde, 1998;Wilde et al, 2005;Zhao et al, 2008aZhao et al, ,b, 2011, charnockites are in the west (Peng et al, 2012a), monzogranites and biotite granites are mostly in the east (Guo and Li, 2009;Lu et al, 2004a,b;Wu et al, 2007;Zhao et al, 2006), with some in the center (Geng et al, 2000;Zhao et al, 2002a), and S-type granites are mainly in the west (Peng et al, 2012a). Some 1930-1880 Ma aluminum-rich (S-type?)…”

“…The 2200-1880 Ma granitic rocks include a variety of granodiorites, charnockites, tonalites, monzogranites, biotite granites and garnet/ sillimanite-bearing granites (Geng et al, 2000;Guo and Li, 2009;Kröner et al, 2005;Li and Zhao, 2007;Liu et al, 2009b;Lu et al, 2004a,b;Peng et al, 2012a;Wan et al, 2006;Wang and Wilde, 2002;Wang et al, 2010c;Wilde, 1998;Wu et al, 2007;Yang et al, 2009Yang et al, , 2011Zhao et al, 2002aZhao et al, , 2006Zhao et al, , 2008aZhao et al, ,b, 2011. Some of these granitic rocks are deformed with gneissic schistosity conformable with that of their host rocks (e.g., Mafeng monzogranites, Li and Zhao, 2007; tonalites in the Jiehekou Group/Complex, Zhao et al, 2008b); whereas others are largely undeformed (e.g., Tonghua A-type granites, Lu et al, 2004b; and Lingyunkou A-type granites, Zhao et al, 2011).…”