大兴安岭中段天险沟石英二长斑岩的成因——锆石U-Pb年龄、地球化学和Sr—Nd同位素特征
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本文为内蒙古自治区地质勘查基金项目“呼伦贝尔市沃力嘎沟等四幅1∶5万区域矿产地质调查”(编号:NMKD2014-22)的成果


Petrogenesis of the quartz monzonite porphyry in Tianxiangou,central Great Hinggan Mountain——Constraints from zircon U- Pb dating, geochemical and Sr—Nd isotopic characteristics
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    摘要:

    本文通过岩石学、锆石U- Pb年代学和地球化学等研究,对大兴安岭中段天险沟石英二长斑岩的成因、物质来源和构造背景进行了探讨。通过锆石LA-ICPMS U-Pb定年法,得到天险沟石英二长斑岩的年龄为124.4±1.0 Ma,时代为早白垩世早期。天险沟石英二长斑岩属碱性、准铝质岩,里特曼指数σ为3.86~5.10,K2O+Na2O=9.14%~10.35%,钾钠比为0.93~1.0,A/CNK=0.76~0.93,成因类型为I型花岗岩。岩石富集La、Ba、Ce、U等大离子亲石元素,相对亏损Hf、Zr等高场强元素;(La/Yb)N=11.72~13.90,分馏明显,轻稀土富集,而重稀土亏损,Nb、Ta负异常,具岛弧花岗岩的地球化学特征。δEu=1.00~1.59。\[n(87Sr)/n(86Sr)\]i=0.705065,εNd(t)=1.93,源区可能为上地幔。结合大兴安岭地区中生代地壳演化背景,认为天险沟石英二长斑岩形成于与洋壳俯冲有关的火山弧环境,区域应力场由挤压向伸展转换,岩浆源区为上地幔。

    Abstract:

    Based on petrology, zircon U-Pb chronology and geochemistry, this article discusses the genesis, material source and tectonic background of tianxiangou quartz monzonite porphyry in central section of Great Hinggan Mountains. According to zircon LA-ICPMS U-Pb dating method, the age of Tianyingou quartz monzonite porphyry is 124.4 ± 1.0 Ma and the age is Early Cretaceous. Tianxiangou quartz monzonite porphyry belongs to alkaline and quasi aluminous rocks with Rittman index σ= 3.86 ~ 5.1, total alkali (Na2O + K2O) =9.14% ~ 10.35%, K2O / Na2O = 0.93 ~ 1.0, A/CNK=0.76 ~ 0.93, and the genetic type is I-type granite. The rocks are rich in large ion lithophile elements such as La, Ba, Ce and U, and relatively deficient in high field strength elements such as Hf and Zr; (La/Yb)N=11.72 ~ 13.90, with obvious fractionation, enrichment of light rare earths, loss of heavy rare earths, negative Nb and Ta anomalies, showing the geochemical characteristics of island arc granites.δ Eu=1.00~1.59. \[n(87Sr) /n (86Sr)\]i=0.705065, ε Nd (t) =1.93, the source area may be the upper mantle. Combined with the Mesozoic crustal evolution background in the Great Hinggan Mountains, it is considered that the Tiandanggou quartz monzonite porphyry was formed in a volcanic arc environment related to the subduction of the oceanic crust, the regional stress field was transformed from compression to extension, and the magma source was the upper mantle.

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贺晓天,黄海涛,俎新许,张焕,何鹏,刘朝阳,赵亚南,李福斌.2022.大兴安岭中段天险沟石英二长斑岩的成因——锆石U-Pb年龄、地球化学和Sr—Nd同位素特征[J].地质论评,68(3):2022062016,[DOI].
HE Xiaotian, HUANG Haitao, ZU Xinxu, ZHANG Huan, HE Peng, LIU Chaoyang, ZHAO Yanan, LI Fubin.2022. Petrogenesis of the quartz monzonite porphyry in Tianxiangou,central Great Hinggan Mountain——Constraints from zircon U- Pb dating, geochemical and Sr—Nd isotopic characteristics[J]. Geological Review,68(3):2022062016.

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  • 收稿日期:2021-12-21
  • 最后修改日期:2022-05-30
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  • 在线发布日期: 2022-06-20
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