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现代地质 ›› 2020, Vol. 34 ›› Issue (01): 64-73.DOI: 10.19657/j.geoscience.1000-8527.2019.013

• 岩石学 • 上一篇    下一篇

南祁连擦勒特地区志留纪巴龙贡嘎尔组火山岩地球化学特征及其地质意义(撤回)

柴云(), 赵娟, 李德彪, 马正婷, 安朝, 魏有宁, 王成勇   

  1. 青海省地质调查局,青海 西宁 810001
  • 收稿日期:2018-12-25 修回日期:2019-03-12 出版日期:2020-03-05 发布日期:2020-03-07
  • 作者简介:柴 云,男,助理工程师,1990年出生,资源勘查工程专业,从事区域地质矿产调查及地勘项目综合管理类工作。Email: 511011615@qq.com
  • 基金资助:
    中国地质调查局地质矿产调查项目(1212011221148)

Geochemical Characteristics and Geological Significance of Silurian Volcanic Rocks of Balonggongge’er Formation in Southern Qilian Mountain(withdrawal)

CHAI Yun(), ZHAO Juan, LI Debiao, MA Zhengting, AN Zhao, WEI Youning, WANG Chengyong   

  1. Qinghai Geological Survey, Xining, Qinghai 810001, China
  • Received:2018-12-25 Revised:2019-03-12 Online:2020-03-05 Published:2020-03-07

摘要:

擦勒特地区志留纪巴龙贡嘎尔组火山岩由火山碎屑岩、火山熔岩组成,为一套钙碱性系列组合。采用LA-MC-ICP-MS锆石U-Pb测年,在该组变质英安岩中首次获得206Pb/238U加权平均年龄为(418.7±2.7) Ma,确定该套火山岩形成于晚志留世。地球化学特征显示,该套火山岩具有高Al2O3、低TiO2的特征,稀土总量(ΣREE)较高,轻、重稀土元素分馏明显,表现为轻稀土元素(LREE)富集,铕(Eu)负异常明显,Rb、Th、K等元素富集明显,La、Ce、Ba、Nd等元素略显富集,Nb、Sr、P、Ti等元素亏损明显。综合分析认为,该区火山岩形成于活动大陆边缘(陆缘弧)环境。

关键词: 南祁连, 巴龙贡嘎尔组, 火山岩, LA-MC-ICP-MS锆石U-Pb年龄

Abstract:

Volcanic rocks of the Balonggongge’er Formation in the Calete area are composed of calc-alkaline pyroclastic rocks and volcanic lavas. LA-MC-ICP-MS zircon U-Pb dating on the meta-dacite of this formation yielded an age of the Late Silurian according to the weighted average age of (418.7±2.7) Ma, representing the first age reported for this formation. Geochemical data show that the volcanic rocks are featured by their high Al2O3 and low TiO2, relatively high total rare earth element contents (ΣREE), LREE enrichments, distinct LREE/HREE fractionation and negative Eu anomalies. The rocks show marked enrichments in Rb, Th and K, slight enrichments in La, Ce, Ba and Nb, and depletions in Nb, Sr, P and Ti. Comprehensive analysis indicates that the volcanic rocks in this area were formed in a continental arc setting.

Key words: southern Qilian, Balonggongge’er Formation, volcanic rock, LA-MC-ICP-MS zircon U-Pb dating

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