地学前缘 ›› 2018, Vol. 25 ›› Issue (6): 264-276.DOI: 10.13745/j.esf.sf.2018.9.9

• 岩石成因与区域演化 • 上一篇    下一篇

燕山地区寿王坟杂岩体锆石U-Pb年代学、Hf同位素和地球化学特征及其地质意义

董朋生，董国臣，孙转荣，李华伟，王树树，王伟清，耿建珍   

  1. 1. 中国地质大学(北京) 地球科学与资源学院, 北京 100083 
    2. 中国地质调查局 天津地质调查中心, 天津 300170
  • 收稿日期:2018-08-20 修回日期:2018-09-02 出版日期:2018-11-30 发布日期:2018-11-30
  • 作者简介:董朋生(1995—)，男，博士研究生， 矿物学、岩石学、矿床学专业。 E-mail:psd@cugb.edu.cn
  • 基金资助:
    国土资源部中央地质勘查基金项目“东部片区成果集成及战略选区研究”(20180202)；国家重点研发计划项目(2016YFC0600502)；中国地质大学(北京)燕山地质实践教学后备基地建设项目(2015-ms129)

Zircon U-Pb chronology, Hf isotopic compositions, geochemistry characteristics and geological significance of Shouwangfen complex in Yanshan region.

DONG Pengsheng,DONG Guochen,SUN Zhuanrong,LI Huawei,WANG Shushu,WANG Weiqing,GENG Jianzhen   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China 
    2. Tianjin Center of Geological Survey, China Geological Survey, Tianjin 300170, China
  • Received:2018-08-20 Revised:2018-09-02 Online:2018-11-30 Published:2018-11-30
  • Contact: 董国臣(1962—),男,教授,博士生导师,主要从事岩石学及矿床学研究。E-mail:donggc@cugb.edu.cn
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摘要： 燕山地区寿王坟杂岩体由石英闪长岩、石英二长岩组成。LA-ICP-MS锆石U-Pb年代学研究表明，石英闪长岩和石英二长岩形成于(128±1) Ma，是早白垩世岩浆活动的产物。对比区域岩浆作用特点显示，研究区岩浆作用与华北克拉通东部大规模岩浆活动时代相近。寿王坟杂岩体富碱(Na2O+K2O含量为8.48%~9.06%(质量分数)，属钾玄质系列(K2O 3.87%~4.96%)、准铝质岩石(A/CNK=0.69~0.89，A/NK=1.19~1.35)，富集Rb、Ba、Sr等元素，亏损Nb、Ta、Th、P等元素，具高Sr((684~1 018)×10-6)和Ba((1 163~1 506)×10-6)、高Sr/Y(43~102)和La/Yb(31~91)比值、低Y((7.19~16.55)×10-6)和Yb((0.47~1.28)×10-6)、富集LREE、基本无Eu异常等特征。εHf(t)值较低，石英闪长岩εHf(t)=-18.1~-11.1，石英二长岩εHf(t)=-18.6~-13.2。研究认为寿王坟杂岩体主要形成于早白垩世古太平洋板块向欧亚大陆俯冲背景下的伸展环境，来源于古元古代地壳物质的部分熔融，并有不同程度富集地幔的贡献。Sr/Y值与SiO2含量呈正相关表明其不具源区特征，主要是岩浆在侵位过程中富水岩浆分异演化发生角闪石等矿物的结晶分异作用造成的。

 

关键词: 高Sr/Y, 锆石U-Pb年代学, 地球化学, 燕山地区, 寿王坟杂岩体

Abstract: The Shouwangfen complex is composed of biotite quartz diorite and quartz monzonite. Our LA-ICP-MS zircon U-Pb chronological study shows the quartz diorite and quartz monzonite ages are 128±1 Ma, suggesting the Shouwangfen complex formed in the Early Cretaceous, closely coincides with the period of large-scale magmatic activity in the eastern North China Craton. The Shouwangfen complex belongs to the quasi-aluminous rock of alkaline series (A/CNK ranged 0.690.89, A/NK ranged 1.191.35, Na2O+K2O ranged 8.48%9.06% and K2O ranged 3.874.96%), enriched in Rb, Ba and Sr and depleted in Nb, Ta, Th and P. It has the characteristics of high Sr ((6841018)×10-6) and Ba ((11631506)×10-6) contents, high Sr/Y(43102) and La/Yb (3191) values, low Y ((7.1916.55)×10-6) and Yb ((0.471.28)×10-6) contents, enrichment of light rare-earth element (LREE), and no Eu anomalies. The quartz diorite and quartz monzonite have low εHf(t) values of -18.1 to -11.1 and -18.6 to -13.2, respectively. Geochemical characteristics indicate the Shouwangfen complex formed under the tectonic setting of extension environment created by the ancient Pacific plate subduction to the Eurasian continent. The complex originated from the partial melting of Paleoproterozoic crustal material with varying contributions from enriched mantle. The high Sr/Y value, however, is not a source feature due to its positive correlation with SiO2, but a result of fractionation during emplacement.

Key words: high Sr/Y value, zircon U-Pb chronology, geochemistry, Yanshan region, Shouwangfen complex

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