| 孙志远,孙永刚,龙灵利,王玉往,万建宇,张波涛,范晶,丁然然,王路豪.新疆东天山银帮山地区中酸性火山岩地球化学特征及其地质意义[J].矿产勘查,2025,16(5):955-968 |
| 新疆东天山银帮山地区中酸性火山岩地球化学特征及其地质意义 |
| Geochemical characteristics of the intermediate-felsic volcanic rocks from Yinbangshan area in eastern Tianshan, Xinjiang and its geological implication |
| 投稿时间：2024-11-02 |
| DOI：10.20008/j.kckc.202505002 |
| 中文关键词: 中酸性岩 地球化学 Sr-Nd同位素 东天山 银邦山中图分类号:P597文献标志码:A文章编号:1674-7801(2025)05-0955-14 |
| 英文关键词: intermediate-felsic volcanic rocks geochemistry Sr-Nd isotopes eastern Tianshan Yinbangshan |
| 基金项目:本文受国家重点基础发展研究计划项目(2014CB440803)资助。 |
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| 中文摘要: |
| 银帮山地区位于东天山阿奇山—雅满苏构造带东部，本文对该区的中酸性火山岩进行研究，以期探讨岩石成因及为东天山地区构造演化提供重要支撑。研究结果表明，银帮山地区以安山岩、英安岩、流纹岩、流纹斑岩以及角砾凝灰岩和晶屑凝灰岩为主，岩石地球化学特征显示火山岩具有高的 SiO(2 54.04%～82.76%，平均为 68.85%)和 Na2O+K2O(6.07%~10.14%)、贫 MgO(0.15%~3.59%)和 FeOT(0.34%~7.98%)特征，为准铝-弱过铝质(A/CNK=0.69~1.30)的高钾钙碱性系列岩石。岩石具有相对富集轻稀土和大离子亲石元素、亏损重稀土和高场强元素的特征，显示与形成于弧环境下的 I型花岗岩类似。同位素特征显示火山岩具有低的 Sr同位素初始比值和正的 εNd(t)值，暗示其为地幔岩浆演化后的产物，可能来源于地幔玄武质岩浆。结合前人综合研究认为银帮山地区中酸性岩形成于与俯冲有关的靠近活动大陆边缘的弧前盆地环境。 |
| 英文摘要: |
| Yinbangshan area is located in the eastern Aqishan-Yamansu tectonic belt of eastern Tianshan,Xinjiang. Intermediate-felsic volcanic rocks in the Yinbangshan area were studied to discuss petrogenesis and toprovide evidence for tectonic evolution of eastern Tianshan. The results reveal that Yamansu Formation in Yinbang.shan is mainly composed of dacite, rhyolite, rhyolite porphyry, breccia tuff, and crystalline tuff. The geochemicalcharacteristics show that these volcanic rocks have high SiO2 (54.04%-82.76%, 68.85% on average) and Na2O+K2O (6.07%-10.14%), low MgO (0.15%-3.59%) and FeOT (0.34%-8.51%), and belong to high K2O (3.87%-9.98%),metaluminous-peraluminous (A/CNK=0.68-1.30), calc-alkaline series. The volcanic rocks are generally enrichedin LREE relative to the HREEs with negative europium anomalies in the chondrite-normalized pattern. They are en.riched in large ion lithophile elements and depleted in high field strength elements in the primitive mantle-normalized trace element diagram, indicating similar geochemical characteristics to I-type granitoids. Isotope char.acteristics indicate that volcanic rocks have low initial Sr isotope ratios and positive εNd(t) values, suggesting thatthey are products of mantle magma evolution and may have been formed through crystallization differentiation ofmantle basaltic magma. We suggest that volcanic rocks from Yinbangshan area were formed in fore-arc basin set.ting that formed in close to active continental margin island arc in subduction zone. |
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