In this paper, we report new whole-rock geochemical and zircon U-Pb data for monzogranites in the NE Xing＇an block. These data constrained the petrogenesis of C type （high Sr/Y） adakitic rocks and showed the spatia...In this paper, we report new whole-rock geochemical and zircon U-Pb data for monzogranites in the NE Xing＇an block. These data constrained the petrogenesis of C type （high Sr/Y） adakitic rocks and showed the spatial extent of the influence of the Mongol-Okhostsk ocean tectonic regime and the collision between the Jiamusi Massif and Songliao Terrane. New zircon laser-ablation inductivity coupled plasma mass spectrometry （LA-ICP-MS） U-Pb data indicated that the monzogranites in the studied area were emplaced in the Early Jurassic （～ 180 Ma）. These rocks were characterized by unusally high SiO2 （≥67.49）, and Sr （461-759 ppm）, but strikingly low Y （4.63-8.06 ppm） and HREE （∑HREE = 3.83-6.49 ppm, Yb = 0.5-0.77 ppm） contents, with therefore high Sr/Y （67.2-119） and （La/Yb）N （29.7-41.5） ratios, showing the geochemical characteristics of C type adakitic granite. The data displayed negligible Eu anomalies （Eu/Eu^＊ =0.77-1.08）, LREE-enriched and pronounced negative Nb and Ta anomalies. The C-type adakites in the studied area were most likely derived from the partial melting of a thickened lower continental curst. The magma source is most likely dominated by amphibolites and garnet amphibolites. In combination with previously-reported data from igneous rocks from the Mesozoic in NE China, we conclude that the Xing＇ an block was influenced by the Mongol-Okhotsk subduction tectonic system, and experiences compressive settings from the amalgamation of the Jiamusi block in the east of the CAOB.展开更多
基金supported by the regional geology and mineralization research program of Heilongjiang province (HLJKD201417)
文摘In this paper, we report new whole-rock geochemical and zircon U-Pb data for monzogranites in the NE Xing＇an block. These data constrained the petrogenesis of C type （high Sr/Y） adakitic rocks and showed the spatial extent of the influence of the Mongol-Okhostsk ocean tectonic regime and the collision between the Jiamusi Massif and Songliao Terrane. New zircon laser-ablation inductivity coupled plasma mass spectrometry （LA-ICP-MS） U-Pb data indicated that the monzogranites in the studied area were emplaced in the Early Jurassic （～ 180 Ma）. These rocks were characterized by unusally high SiO2 （≥67.49）, and Sr （461-759 ppm）, but strikingly low Y （4.63-8.06 ppm） and HREE （∑HREE = 3.83-6.49 ppm, Yb = 0.5-0.77 ppm） contents, with therefore high Sr/Y （67.2-119） and （La/Yb）N （29.7-41.5） ratios, showing the geochemical characteristics of C type adakitic granite. The data displayed negligible Eu anomalies （Eu/Eu^＊ =0.77-1.08）, LREE-enriched and pronounced negative Nb and Ta anomalies. The C-type adakites in the studied area were most likely derived from the partial melting of a thickened lower continental curst. The magma source is most likely dominated by amphibolites and garnet amphibolites. In combination with previously-reported data from igneous rocks from the Mesozoic in NE China, we conclude that the Xing＇ an block was influenced by the Mongol-Okhotsk subduction tectonic system, and experiences compressive settings from the amalgamation of the Jiamusi block in the east of the CAOB.
