Source of Mesozoic intermediate-felsic igneous rocks in the North China craton: Granulite xenolith evidence

Enriched continental flood basalts from depleted mantle melts: modeling the lithospheric contamination of Karoo lavas from Antarctica

“…Comprehensive geochemical data for lower crust of the area are not available, and thus, our preliminary dataset included the granulites of the Ross Orogen of northern Victoria Land (Talarico et al 1995;Antonini et al 1999), granulites from the North China Craton that is characterized by an Archean core and is lithologically similar to the basement of the study area (Yu et al 2003;Ying et al 2010;Jiang et al 2011), and a global average lower crust composition (Rudnick and Gao 2003).…”

Zircon U-Pb geochronology, geochemistry and Sr-Nd-Pb isotopes from the metamorphic basement in the Wuhe Complex: Implications for Neoarchean active continental margin along the southeastern North China Craton and constraints on the petrogenesis of Mesozoic granitoids

“…Thus, the Nushan granulite xenoliths were considered as dominantly derived from the late Archean metamorphic basement and subordinately from the mafic layer which was accreted to the basement during late Mesozoic lithospheric thinning (Huang et al, 2004). However, Jiang et al (2011) proposed an alternative interpretation that the granulite xenoliths (both sample NS202 and other xenoliths) are most likely remnants of an ancient lower crust on the basis of Nd isotope and other evidence.…”

“…In contrast, most of the granulite xenoliths in Quaternary basanites from Nushan in the southeastern margin of the NCC show compositional features that are markedly different from those of the mafic granulites from Hannuoba, albeit resembling the Archean granulite terrains with only few granulite xenoliths possibly being formed by basaltic underplating during the Mesozoic (117e140 Ma, sample NS202) (Huang et al, 2004). However, on the basis of highly negative 3(Nd)(t) (À27.7 to À34.7) values and other geochemical data, Jiang et al (2011) proposed that both sample NS202 and the other xenoliths in Nushan are most likely remnants of ancient lower crust and further suggested that the Mesozoic zircon ages in some of these might reflect metamorphism related to the Mesozoic magmatism rather than Mesozoic underplating (similar to some of the granulite xenoliths in the Zhangjiakou region of the northern NCC). These authors considered that many granitic plutons in the southeastern margin of the NCC with ages of 112e160 Ma were derived from the lower crust on the basis of data from Yang et al (2010).…”

“…However, only few studies have been carried out on the southeastern margin of the NCC, especially on the metamorphic basement. Both granulite xenoliths and basement rocks are widely distributed in the NCC (e.g., Fan and Liu, 1996;Fan et al, 1998Fan et al, , 2005Chen et al, 2001;Liu et al, 2001Liu et al, , 2004bZhai et al, 2001;Zhou et al, 2002;Wilde et al, 2003;Huang et al, 2004;Ying et al, 2010;Jiang et al, 2011;Zhang, 2012), and the published data indicate that there are significant differences in age, composition, occurrence and equilibrium pressure between the granulite xenoliths and the high grade basement rocks. In terms of zircon ages, several intermediate-mafic granulite xenoliths entrained in the Tertiary Hannuoba alkali basalts at the northern segment of the NCC (Zhangjiakou region) have been considered to be formed by Mesozoic basaltic underplating (e.g., Fan et al, 1998Fan et al, , 2005.…”

“…In terms of zircon ages, several intermediate-mafic granulite xenoliths entrained in the Tertiary Hannuoba alkali basalts at the northern segment of the NCC (Zhangjiakou region) have been considered to be formed by Mesozoic basaltic underplating (e.g., Fan et al, 1998Fan et al, , 2005. Recent studies by Jiang et al (2007Jiang et al ( , 2011 and addressed the age and compositional differences between the granulite xenoliths and the adjoining granulite terrains, and the petrogenetic link between late Mesozoic intermediate-felsic igneous rocks and the granulite xenoliths and high grade terrains. These authors proposed that the source rocks for the Mesozoic intermediate-felsic magmas in the Zhangjiakou region were most likely late Archean lower crustal rocks similar in chemical and isotopic composition to rocks in the granulite terrains, and that some of the mafic granulite xenoliths such as those entrained in the Hannuoba basalts also in the Zhangjiakou region could be restites left behind after the partial melting of the late Archean lower crust.…”