Isotopic Characteristics and Its Significance of the Xinlin Town Pluton,Great Hinggan Mountains
Isotopic Characteristics and Its Significance of the Xinlin Town Pluton,Great Hinggan Mountains
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发表时间：
2008
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通讯作者：
Ji-heng Zhang
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作者：
Ji-heng Zhang
新林岩体位于大兴安岭北方，岩石类型为花岗闪长岩、二长花岗岩、石英二长花岗岩和碱长花岗岩，岩石学和地球化学特征表明，该岩体为高钾钙碱性I型花岗岩，锆石LA-ICP-MS U-Pb定年结果分别为（132±3）Ma和（131±3）Ma。岩石的Sr-Nd同位素组成虽然比较均匀，但eHf（t）值变化较大，变化范围在1.32 ~ 8.32之间;产出的Nd和Hf模式年龄为新元古代，同位素数据表明花岗岩岩浆主要来自新元古代的新生增生地壳同位素特征表明额尔古纳地体至少在新元古代增生，而兴安地体则在新元古代-早古生代增生，表明它们具有不同的构造性质和演化历史。
The Xinlin Town pluton locates in the northern Great Hinggan Mountains.Lithologically,it comprises granodiorite,adamellite,quartz-monzodiorite and alkaline-feldspar granite,with locally fine-grained gabbroic and dioritic enclaves.Petrological and geochemical characteristics indicate that the pluton is high-K calc-alkaline I-type granite.Zircon LA-ICP-MS U-Pb dating of two granodiorites yielded emplacement ages of(132±3)Ma and(131±3)Ma.The ages indicate that the pluton was the product of the Early Cretaceous magmatic event.Though Sr-Nd isotopic compositions of the samples are relatively uniform,their eHf(t) values are relatively varied,ranging between 1.32 and 8.32;the yielded Nd and Hf model ages are Neoproterozoic.The isotopic data indicate that the granitic magma mainly originated from the juvenile Neoproterozoic accreted crustal materials with the involvements mantle components.The isotopic characteristics indicate that the Erguna terrain accreted in Neoproterozoic at least,but the Xing'an terrain accreted in Neoproterozoic-Phanerozoic.It suggests that they have the different tectonic natures and evolvement history.