论文摘要
We report zircon U-Pb geochronology, whole-rock geochemistry, mineral chemistry and zircon Hf isotopic compositions analytical research of the Hailin pluton from the Mudanjiang region in the southeastern Songnen-Zhangguangcai Range Massif, which to confirm the formation ages, petrogenesis and related geodynamic mechanisms of the Hailin pluton, further to provide important constraint for the tectonic evolution of the Mudanjiang Ocean between the Songnen-Zhangguangcai Range and the Jiamusi massifs. Through the geological survey and petrographic study, we find that the Hailin pluton is composed of the host granitoids（monzogranites and granodiorites） and the mafic microgranular enclaves（MMEs; diorites）. The MMEs are common in the host granitoids and are characterized by irregular spheroidal shapes, with sharp, rounded, or irregular transitional contacts, chilled margins, acicular apatites. It can preliminarily determine that the Hailin pluton was the product of the magma mixing. Then mineral chemistry, whole-rock geochemistry and zircon U-Pb dating are conducted to further support the role of magma mixing in the petrogenesis of the Hailin pluton. The evidence is as follows:（1） the mineral compositions of plagioclase and amphibole in MMEs are in disequilibrium. And the plagioclase is composed of oligoclase-andesine, suggesting typical reverse zoning characteristic. The amphibole can be classified as magnesiohornblende and tschermakite and belongs to crust-mantle amphibole;（2） the geochemical characteristics of the Hailin pluton show that the MMEs and the host granitoids plot along the trend of mixing line between mantle and crustal magmas in the Fe2O3T-MgO diagram. The MMEs and the host granitoids show a linear relationship in the Harker diagrams and a hyperbolic relationship in the noncommon denominator ratio diagrams. The characteristics of trace elements are similar but the ratios are different, which reflects that the MMEs and their host granitoids were from different magma sources and underwent a magma mixing process;（3） Zircon U-Pb ages data show that the diagenetic ages of the host granitoids in Hailin pluton were 215～219 Ma, and those of the MMEs were 221 Ma, suggesting they were both formed during the Late Triassic. All the above evidence shows that the Hailin pluton has petrogenesis of magma mixing, and the MMEs were formed by the mixing of felsic magma and mafic magma. As for the origin of felsic magma and mafic magma which formed the Hailin pluton, here we take the host granitoids as the felsic end-member rocks. The host granitoids are characterized by high silica content（SiO2 = 63.18～70.44 wt.%）, high alkali content（Na2O+K2O=6.59～7.95 wt.%）, low MgO（0.69～1.94 wt.%） and low Fe2O3T（2.39～4.68 wt.%）. They are enriched in light rare earth elements（LREEs） and depleted in heavy rare earth elements（HREEs）, with total rare earth elements of 88.55～116.29 ppm, LREE/HREE ratios of 7.47～13.43 and（La/Yb）N values of 5.80～18.62. They are also en
论文目录
文章来源
类型: 国际会议
作者: ZHAO Di,GE Wenchun,YANG Hao,DONG Yu,JI Zheng,HE Yue,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,地质学
单位: Jilin UniversityEighth Geological Brigade of Hebei Geology and Mineral Resources Exploration Bureau
分类号: P588.1;P597.3
DOI: 10.26914/c.cnkihy.2019.028315
页码: 72-73
总页数: 2
文件大小: 173k
下载量: 2