Mature Archean continental crust in the Yangtze craton: Evidence from petrology, geochronology and geochemistry

Abstract

Previous studies have shown that the Archean basement is widely distributed throughout the Yangtze craton. To date, however, Archean basement terrains have not been found, except for a few Kongling high-grade metamorphic terrains in the Huangling dome that have been confirmed to be of Archean age. To further understand the basement component and crustal evolution of the Yangtze craton, we carried out a petrological, geochronological and geochemical study of the Jinshan K-feldspar granite emplaced within the Yangpo Group, located in Huji Town, Zhongxiang City, Hubei Province. Results indicate that the zircon SHRIMP U-Pb age of the Jinshan granite is 2655±9 Ma, placing it within the middle Neoarchean. Chemically, this pluton yields abundant silica and alkalis and is depleted in Ca, Mg and Ti. Furthermore, it is enriched in Rb, Th, Ga, Y and Zr, depleted in Sr, Ba, Nb and Ta, and especially lacking in Eu. High ratios of FeO*/MgO (32.0 to 58.7) and 10 4 ×Ga/Al (3.19 to 3.41) were also found. The pluton exhibits characteristics typical of A-type granites with crustal source magmas. Moreover, the meta-sedimentary rock association of the Yangpo Group, into which the pluton intruded, clearly shows relatively stable depositional environments of a shallow shelf sequence. Therefore, before the middle Neoarchean, the Yangtze craton contained mature continental crust. This breakthrough discovery opens a new window on the study of the formation and evolution of the Yangtze craton basement.

Mid-Neoproterozoic angular unconformity in the Yangtze Block revisited: Insights from detrital zircon U–Pb age and Hf–O isotopes

“…Other late Neoarchean to Paleoproterozoic basement rocks are mainly exposed along the northern margin of the Yangtze Block, including ca. 2.65 Ga K-feldspar granite emplaced within the Yangpo Group (Wang et al, 2013a), ca. 2.5 Ga gray gneiss from the Douling complex Wu et al, 2014), ca.…”

“…3), suggesting a long-distance transport from their provenances and/or multi-cycled sedimentary process. In the Yangtze Block, the Archean rocks crop out sporadically in the Kongling TTG complex, Jinshan K-feldspar granite and Douling complex, which have been dated at 3.45-2.6 Ga (Qiu et al, 2000;Jiao et al, 2009;Gao et al, 2011;Chen et al, 2013a;Guo et al, 2014), 2655 ± 9 Ma (Wang et al, 2013a), and ca. 2.5 Ga Wu et al, 2014), respectively.…”

Geochronology and geochemistry ofca. 2.48 Ga granitoid gneisses from theYudongzi Complexin the north‐westernYangtze Block,China

“…The ca . 2.7–2.6 Ga magmatism might have played an important role in extensively impacting the Yangtze Block (K. Chen et al, ; Hui et al, ; Z. J. Wang et al, ; Zhou et al, ). In the Kongling Complex, the orthogneisses display A‐type granite geochemical features and constitute the major magmatic rocks formed during ca .…”

“…2.8–2.7 Ga in the north‐eastern Yangtze Block (Z. J. Wang et al, ) and is considered to have developed in a relatively stable tectonic setting of a passive continental margin or in a craton basin (Z. J. Wang et al, ). In the northern and southern part of the Yangpo Group, Neoarchean A‐type granites in stocks and apophyses intruded into the Yangpo Group (Z. J. Wang et al, ; Zhou et al, ). They are suggested to have been derived from reworking of ca .…”

“…3.2 Ga juvenile crust and to record the craton stabilization of the eastern Yangtze Block at ca . 2.85, 2.73, and 2.65 Ga (Z. J. Wang et al, ; Zhou et al, ; Z. J. Wang et al, ). Palaeoproterozoic intrusions into the Yangpo Group are composed primarily of gneissic K‐feldspar granites and gneissic monzogranites (Z. J. Wang et al, ; L. J. Zhang, Ma, Wang, She, & Wang, ), interpreted to have resulted from reworking ancient crust at ca .…”