The authors report zircon U-Pb geochronological, whole-rock geochemical and zircon Lu-Hf isotope data for the hornblende gabbro within the Khanka Massif, with the aim of constraining its formation time and petrogenesi...The authors report zircon U-Pb geochronological, whole-rock geochemical and zircon Lu-Hf isotope data for the hornblende gabbro within the Khanka Massif, with the aim of constraining its formation time and petrogenesis. The zircon U-Pb dating shows that 206 pb^238 Pb ages of zircons from the hornblende gabbro range from 120 to 129 Ma, yielding a weighted mean age of 123±2 Ma, i.e., the Early Cretaceous. The hornblende gabbro has SiO2 of 44.77%-46.58% and belongs to the tholeiitie series on FeOt/MgO-SiO2 diagram. It dis-plays a right-inclined REE pattern with （La/Yb）N ratios of 3.44 to 4.42. The trace element spidergram shows that they are enriched in large ion lithophile elements （LILE） such as Rb, Th, U, K and Pb, and depleted in high field strength elements （HFSE） such as Nb, Ta, Ti and P, indicating an affinity to arc igneous rocks. The ettf（t） values of zircons vary from -2.6 to ＋ 3.9 and Hf model ages （TDM1 ） range from 622 to 883 Ma. These geochemical characteristics indicate that primary magma of the hornblende gabbro could be derived from partial melting of young mantle material acereted during the Neoproterozoie. Combined with the Early Creta-ceous igneous rock assemblages in NE Asia. It is concluded that the hornblende gabbro formed in an active con-tinental margin related to the westward subduction of the Paleo-Paeific Plate beneath the Khanka Massif.展开更多
基金Supported by National Natural Science Foundation of China(No.41330206)
文摘The authors report zircon U-Pb geochronological, whole-rock geochemical and zircon Lu-Hf isotope data for the hornblende gabbro within the Khanka Massif, with the aim of constraining its formation time and petrogenesis. The zircon U-Pb dating shows that 206 pb^238 Pb ages of zircons from the hornblende gabbro range from 120 to 129 Ma, yielding a weighted mean age of 123±2 Ma, i.e., the Early Cretaceous. The hornblende gabbro has SiO2 of 44.77%-46.58% and belongs to the tholeiitie series on FeOt/MgO-SiO2 diagram. It dis-plays a right-inclined REE pattern with （La/Yb）N ratios of 3.44 to 4.42. The trace element spidergram shows that they are enriched in large ion lithophile elements （LILE） such as Rb, Th, U, K and Pb, and depleted in high field strength elements （HFSE） such as Nb, Ta, Ti and P, indicating an affinity to arc igneous rocks. The ettf（t） values of zircons vary from -2.6 to ＋ 3.9 and Hf model ages （TDM1 ） range from 622 to 883 Ma. These geochemical characteristics indicate that primary magma of the hornblende gabbro could be derived from partial melting of young mantle material acereted during the Neoproterozoie. Combined with the Early Creta-ceous igneous rock assemblages in NE Asia. It is concluded that the hornblende gabbro formed in an active con-tinental margin related to the westward subduction of the Paleo-Paeific Plate beneath the Khanka Massif.
