Petrogenesis and geodynamic setting of the Late Jurassic Queshan adakitic granite, Jiaodong Peninsula, southeastern North China Craton: Zircon U–Pb geochronological, geochemical, and Lu–Hf isotopic evidence

Abstract

Late Mesozoic granites are present throughout the Jiaodong Peninsula in eastern China, but the petrogenesis of these granites, the magma sources, and the geodynamic setting of the magmatism remain unclear. This paper presents new zircon U–Pb geochronological and Lu–Hf isotopic and whole‐rock geochemical data for the Late Jurassic Queshan pluton in the Shandong Peninsula, an area that represents the boundary between the Jiaobei and Sulu ultrahigh‐pressure (UHP) terranes. Laser ablation–inductively coupled plasma–mass spectrometry zircon U–Pb dating yields Late Jurassic ages from 158 ± 1 to 153 ± 1 Ma for the pluton in addition to a small number of inherited zircons that yield ages that cluster at 2410, 1831–1776, 750, and 209–202 Ma. Zircons from different samples have similar 176Hf/177Hf values (0.281926–0.282255) and variably negative εHf (t) values that range from −26.5 to −15.1 (weighted mean of −22.9 ± 0.9). The corresponding two‐stage Hf model ages range from 2,869 to 2,154 Ma, with a weighted mean value of 2,645 ± 54 Ma. These data indicate that the magmas that formed the Queshan pluton were derived from multiple sources, including the lower crust of the North China (NCC) and Yangtze (YC) cratons, as well as collision‐related alkaline rocks. The whole‐rock geochemical compositions of the samples indicate that the granites are weakly peraluminous, are high‐K and calc‐alkaline with I‐type affinities, and have high contents of Sr, low contents of Y and Yb, high (La/Yb)N and Sr/Y values, and positive Eu anomalies (δEu = 1.20–1.65), indicating an adakitic affinity. This indicates that the Queshan granites formed from magmas generated by partial melting of a thickened region of the crust (>50 km) associated with eclogite, garnet amphibolite, or amphibolite residual material. The genesis of the Late Jurassic granites are also likely to have been influenced by the collisional orogeny between the NCC and YC and continued subduction of the Izanagi Plate. Thickening of the lower crust associated with this continental collisional event occurred before the magmatism, with further compression and thickening of the lower crust caused by the low‐angle subduction of the Izanagi Plate beneath northeastern China being the main geodynamic driver of the formation of the granites in this region.

Genesis of the Yangjiakuang gold deposit, Jiaodong peninsula, China: Constraints from S-He-Ar-Pb isotopes, and Sm-Nd and U-Pb geochronology

“…III gold orebody is the largest in the Yangjiakuang deposit and strikes EW, dips to the north at 20-30 °, and has a length of 300 m, and a thickness of 4.2-18.0 m. The gold proven resource is 2.58 t. The grade of gold varies from 2.5 to 4.5 g/t, with an average value of 3.79 g/t. The boundary between the orebody and the ore-bearing rock is not clear and shows a gradual Ding et al, 2015;Li et al, 2020;Dang et al, 2022). 1.…”

“…The initial subduction of the plate was rapid and low angle, generating compressive stress in eastern China (Zhang and Zhang., 2007). This low angle subduction meant that the Izanagi Plate was located below northeastern China, thickening and compressing the already thickened orogenic crust formed by earlier continental collisional events, which caused partial melting of the lower crust and lithospheric delamination (Dang et al, 2022). The loss of the lithospheric keel caused the asthenospheric upwelling, lithospheric extension and thinning in the Early Cretaceous.…”

“…The former includes the Archean tonalite-throndhjemite-granodiorite (TTG) gneisses with small amounts of the Jiaodong Group comprising metamorphic supracrustal rocks and mafic granulite/amphibolite lenses, the Paleoproterozoic Fenzishan and Jingshan Groups, and the Neoproterozoic Penglai Group that consist of metasedimentary rocks (Tang et al, 2007;Yang et al, 2014b;Hao et al, 2020). Geochronological and geochemical studies have revealed that the TTG gneiss, amphibolite, and granulite have protolith ages of ~2.9 to 2.7 Ga, 2.5 Ga, and 2.4 Ga, respectively (Jahn et al, 2008;Xie et al, 2014;Liu et al, 2015;Xie et al, 2015;Dang et al, 2022). The Jingshan Group which is composed of biotite granulite, garnet-biotitegraphite gneiss, dolomitic marble, diopside amphibolite, marble, and biotite-graphite schist (An, 1990;Liu.…”

“…3) The early stage of the Early Cretaceous high-potassium calc-alkaline granodiorite (132-123 Ma, Wang et al, 2014;Liu et al, 2014;Zhao et al, 2018). They are probable mixed crust-mantle components and are represented by the Sanshandao, Shangzhuang, Beijie, Congjia, and Guojialing intrusions (Dang et al, 2022). 4) The late period of the Early Cretaceous alkaline granites and intermediate basic dykes (118-108 Ma, Qiu et al, 2008;Ding et al, 2013;Zhao et al, 2018;Li et al, 2019;Song et al, 2020), which are composed of diorite, granodiorite, and granite assemblages (Yang et al, 2014a;Ding et al, 2015;Dang et al, 2022).…”

“…FIGURE 1Simplified geological map of the Jiaodong Peninsula, showing the distribution of gold deposits, strata, magmatic rocks, and main faults (B). Inset shows tectonic blocks of the North China Craton and the location of the Jiaodong Peninsula (A) (simplified fromDing et al, 2015;Li et al, 2020;Dang et al, 2022). 1.…”