新疆西准噶尔哈拉阿拉特山火山岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及意义
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国家自然科学基金项目(面上项目,重点项目,重大项目)


LA-ICP-MS Zircon Age and Geochemistry of the Aladeyikesai Formation Volcanic Rocks in the Halaalate Mountain of West Junggar, Xinjiang, and Their Tectonic Significance
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    摘要:

    西准噶尔哈拉阿拉特山一带阿腊德依克赛组火山岩主要由玄武岩、玄武安山岩和安山岩组成。玄武岩LA ICPMS锆石UPb年龄为3038±24 Ma,MSWD=082(95%置信度),时代为晚石炭世。火山岩地球化学研究表明,SiO2含量为5105%~5931%,TiO2为090%~133%、全碱K2O+Na2O为397%~807%,富钠贫钾(Na2O/K2O>2)。A12O3为1658%~1984%、MgO为250%~501%,Mg#为3504~4762,主体属于亚碱性系列。稀土元素总量高(∑REE=4112×10-6~7393×10-6),轻、重稀土分馏较强((La/Yb)N=201~533),具轻微负Eu异常(Eu/Eu*=072~088)。相对富集LILE(Ba、Th、K和Sr),轻微亏损HFSE(Zr、Hf),Nb和Ta强烈亏损,Ti轻微亏损。地球化学特征表明岩浆由亏损地幔部分熔融形成,受俯冲带流体的影响,属于博什库尔成吉斯岩浆弧南部活动大陆边缘火山作用的产物。西准噶尔东部增生造山作用滞后于西部,这为进一步认识西准噶尔地区晚古生代构造演化提供了依据。

    Abstract:

    The Late Carboniferous Aladeyikesai Formation volcanic rocks consist of basalt, basaltic andesite and andesite, Halaalate Mountain, western Junggar. The U-Pb zircon LA ICP-MS age of the basalt closely associated volcanic rocks is 303.8±2.4Ma, MSWD=0.82(95% conf.). The volcanic rocks are belong to sub-alkaline series, geochemical study shows the SiO2 ranging from 51.05% to 59.30%, TiO2 ranging from 0.90% to 1.33%, total alkaline (K2O+Na2O) ranging from 3.97% to 8.07%, showing relative rich in sodium, but poor in potassium(Na2O/K2O>2), A12O3 ranging from 16.58% to 19.84%, MgO ranging from 2.50% to 5.01%, and Mg# ranging from 35.04 to 47.62.All samples are characterized by higher rare earth elements(∑REE=41.12×10-6~73.93×10-6) and LREE enrichment((La/Yb)N=2.01~5.33), but weak negative Eu anomaly (Eu/Eu*=0.72~0.88). In addition, they display LILE enrichment (such as Ba、Th、K and Sr), HFSE depletion (Zr and Hf), obvious Nb and Ta negative anomalies, and slight Ti depletion. The geochemical characteristics show that all the rocks from the Aladeyikesai Formation were product of active continental margin arc volcanism in the south of the Boshchekul-Chingiz arc with the source of depletion mantle and mainly affected by the fluid from the subduction zone. So we proposed the orogeny in the east of western Junggar was later than in the west,furthermore, provides evidence for further understanding the tectonic evolution of western Junggar.

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向坤鹏,李永军,李钊,王冉,杨高学,段丰浩,李甘雨.2015.新疆西准噶尔哈拉阿拉特山火山岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及意义[J].地质学报,89(5):843-855.
xiangkunpeng, liyongjun, li zhao, wang ran, yang gao xue, duan feng hao, li gan yu.2015. LA-ICP-MS Zircon Age and Geochemistry of the Aladeyikesai Formation Volcanic Rocks in the Halaalate Mountain of West Junggar, Xinjiang, and Their Tectonic Significance[J]. Acta Geologica Sinica,89(5):843-855.

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  • 收稿日期:2014-11-04
  • 最后修改日期:2014-12-23
  • 录用日期:2014-12-24
  • 在线发布日期: 2015-05-14
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