论文摘要
In recent years, a large number of reports about magma mixing have brought the study of magma mixing in Great Xing’an Range region to a new stage. However, the study of Paleozoic magma mixing in the northern part of Great Xing’an Range area is relatively weak, which restricts our understanding of geodynamic setting. Thus, we undertook zircon U–Pb dating, whole-rock geochemical and zircon Hf isotopic compositions analyses of the Tayuan complex in the northern Xing’an Block, with the aim of addressing the above mentioned question. Through the field geological survey and petrographic study, we find that the Tayuan complex is composed of the host granites（monzogranites） and the mafic microgranular enclaves（MMEs; gabbro-diorites enclaves）. The MMEs are unevenly distributed within the host granites, some of which have plastic rheological characteristics. And some MMEs preserve chilled margins and acicular apatite. Zircon U-Pb ages data show that the diagenetic ages of the host granites in Tayuan complex were 319 Ma, and those of the MMEs were 320 Ma, suggesting they were both formed during the Late Carboniferous. According to the study results of chronology and petrography of the host granites and the MMEs, it can preliminarily determine that the Tayuan complex was the product of the Late Carboniferous magma mixing. The analyses of mineral composition of plagioclase in MMEs show that the plagioclase is composed of andesine, with resorption zone, suggesting a mineral disequilibrium texture which is further support the role of magma mixing in the petrogenesis of the Tayuan complex. Geochemical and zircon Hf isotope data show that the host granites are characterized by high SiO2（66.16～74.18 wt%） and K2O（3.89～4.86 wt%）, low MgO（0.07～0.49 wt%）, CaO（0.14%～0.60%） and P2O5（0.01% ～0.08%）. The host granites are enriched in large ion lithophile elements（LILEs; e.g., Rb, Th, and U） and light rare earth elements（LREEs）, and depleted in high field strength elements（HFSEs; e.g., Nb and Ta） and heavy rare earth elements（HREEs）, with total rare earth elements of 65.53～152.81 ppm, LREE/HREE ratios of 4.44～13.40 and（La/Yb）N values of 5.51～54.96. Zircons from the host granites yield εHf（t） values of-0.46 to +7.1, and two-stage Hf model ages of 899～1382 Ma. Taken together the above chronological, geochemical and zircon Hf isotope characteristics, it is shown that the host granites were derived from the partial melting of Mesoproterozoic–Neoproterozoic lower crust and belong to Itype granitoids. In addition, the MMEs have a restricted range of SiO2（46.29～61.94 wt.%） together with high Mg# values（46–66）, and high concentrations of Ni, Co, and Cr. These MMEs are also characterized by enrichments in LILEs and LREEs, and depleted in HFSEs and HREEs, with total rare earth elements of 161.17～313.39 ppm, LREE/HREE ratios of 6.69～11.27 and（La/Yb）N values of 6.88～17.04. Zircons of the MMEs yield εHf（t） values of-0.69 to +5.33, and single-stage Hf model ages of 748～1076
论文目录
文章来源
类型: 国际会议
作者: HE Yue,GE Wenchun,YANG Hao,DONG Yu,JI Zheng,ZHAO Di,JING Yan
来源: 第九届世界华人地质科学研讨会 2019-06-01
年度: 2019
分类: 基础科学
专业: 地质学,地质学
单位: Jilin UniversityEighth Geological Brigade of Hebei Geology and Mineral Resources Exploration Bureau
分类号: P534.4;P588.11
DOI: 10.26914/c.cnkihy.2019.028293
页码: 36-37
总页数: 2
文件大小: 208k
下载量: 4