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<p>The deep geologic processes between the Xing’an-Mongolian Orogenic Belt and the North China Craton in the Mesozoic are crucial to reveal the magmatic and tectonic evolution and their constraints on mineralization in the Jiapigou-Haigou collage zone. In this paper, We have presented&#xa0;the geochronology, geochemistry and Sr–Nd–Hf isotopic compositions of the Middle Jurassic granitic complexes in the Songjianghe area, Jilin Province. The granitic complexes can be categorized into four groups based on their geologic characteristics, with corresponding zircon U–Pb isotope ages of 177&#xa0;Ma, 172&#xa0;Ma, 169&#xa0;Ma and 168–167&#xa0;Ma, respectively. These granitoids exhibit calc-alkaline to high-K calc-alkaline, metaluminous to weakly peraluminous I-type characteristics, which show relative enrichment in LILEs (Rb, Sr, Ba) and depletion in HFSEs (Nb, Zr). Geochemical analyses reveal high initial <sup>87</sup>Sr/<sup>86</sup>Sr ratios of 0.70633–0.70740, coupled with low εNd(t) values ranging from −10.65 to −13.23. The zircon analyses show similarly negative εHf(t) values ranging from −16.9 to −3.2. The integrated elemental and Hf–Sr–Nd isotopic signatures demonstrate that the primitive magmas of the four group rocks were primarily derived from partial melting of thickened Archean lower crust, with the exception of the Group IV rocks, which exhibit significant evidence of crustal contamination. The residual mineral assemblages during the magma-forming process varied from amphibole to eclogite facies. These findings indicate that magmatism in the Songjianghe region likely resulted from the accretion and delamination of the Archean crust in the collage zone during the subduction of the Paleo-Pacific Plate beneath the Eurasian continent.</p>

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Deep geological processes of the early Middle Jurassic granitic complexes in the Songjianghe area, Jiapigou-Haigou collage zone, Northeast China: Evidence from zircon U–Pb dating, elemental geochemistry and Sr–Nd–Hf isotopes

  • 期刊论文

  • 发表日期：

    2025年7月2日

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  • Xinwen Zhang,
  • Jinggui Sun,
  • Zuochao Lin,
  • Shu Wang,
  • Yunpeng He

摘要

The deep geologic processes between the Xing’an-Mongolian Orogenic Belt and the North China Craton in the Mesozoic are crucial to reveal the magmatic and tectonic evolution and their constraints on mineralization in the Jiapigou-Haigou collage zone. In this paper, We have presented the geochronology, geochemistry and Sr–Nd–Hf isotopic compositions of the Middle Jurassic granitic complexes in the Songjianghe area, Jilin Province. The granitic complexes can be categorized into four groups based on their geologic characteristics, with corresponding zircon U–Pb isotope ages of 177 Ma, 172 Ma, 169 Ma and 168–167 Ma, respectively. These granitoids exhibit calc-alkaline to high-K calc-alkaline, metaluminous to weakly peraluminous I-type characteristics, which show relative enrichment in LILEs (Rb, Sr, Ba) and depletion in HFSEs (Nb, Zr). Geochemical analyses reveal high initial 87Sr/86Sr ratios of 0.70633–0.70740, coupled with low εNd(t) values ranging from −10.65 to −13.23. The zircon analyses show similarly negative εHf(t) values ranging from −16.9 to −3.2. The integrated elemental and Hf–Sr–Nd isotopic signatures demonstrate that the primitive magmas of the four group rocks were primarily derived from partial melting of thickened Archean lower crust, with the exception of the Group IV rocks, which exhibit significant evidence of crustal contamination. The residual mineral assemblages during the magma-forming process varied from amphibole to eclogite facies. These findings indicate that magmatism in the Songjianghe region likely resulted from the accretion and delamination of the Archean crust in the collage zone during the subduction of the Paleo-Pacific Plate beneath the Eurasian continent.