西准噶尔谢米斯台山西缘火山岩岩石地球化学特征及其地质意义  

Geochemical and Geological Significance of the Volcanic Rocks in the West of the Xiemisitai Mountain,West Junggar

作　　者：孙勇[1] 李永军[1] 杨高学[1] 王冉[1] 张胜龙[1] 易善鑫[1] 孙羽[1] 王军年 

机构地区：[1]长安大学地球科学与资源学院,西安710054 [2]新疆地质矿产开发局第七地质大队,新疆乌苏833000

出　　处：《矿物岩石地球化学通报》2015年第2期387-394,共8页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金项目(41273033;41303027);中国地质调查局地质矿产调查专项(1212011120516);中央高校基本科研业务费专项(2014G1271058)

摘　　要：为探讨西准噶尔谢米斯台山西缘新发现的中志留世火山岩的岩石属性和地质特征,对其进行岩石地球化学研究。分析结果显示,岩石以富Si、Sr、Ba为特征且具有较高的Mg^#（55-75）、Sr/Y（28-59）和Ba/La（17.52-49.88）值,K/Na值0.33-0.66,大离子亲石元素（LILE）相对富集,高场强元素（HFSE）相对亏损,其中Nb、Ta、Ti强烈亏损,具有轻微的负铕异常（δEu=0.84-0.99）。上述特征显示其类似日本中新世Setouchi火山岩带中的赞岐岩。结合其他研究,推测该火山岩可能为受俯冲板片熔体交代的地幔源区部分熔融的产物,它与区内相近时期埃达克岩等的共生组合意味着西准北部在中志留世—早泥盆世曾受到热的洋壳俯冲机制的影响,为进一步认识博什库尔-成吉斯岩浆弧的性质及构造演化提供了新的证据。Abstract： Geochemistry studies were conducted to explore properties and geological characteristics of Middle Silurian vol- canic rocks in the west of the Xiemisitai Mountain, West Junggar. The results indicated that the igneous rocks are characterized by high Si, Sr, Ba and Mg^#（55-75）, Sr/Y （28-59）, Ba/La （17.52-49.88）, and K/Na （0.33-0.66）, en- rich large ion lithophile elements （LILE） and deplete high field strength elements （HFSE） especially, Nb, Ta, Ti, and show weak negative Eu anomalies （ δEu = 0.84 - 0.99）. These features are analogous to those of sanukite in the Setouchi volcanic belt, Japan, indicating they originatied from the subduction slab with partial melting of mantle sourced metasomatites. The occurrence of the volcanic rocks and the similar slab-related adakite in this area implied that the northern West Junggar had been affected by hot, subduction-related regime in the Middle Silurian-Early Devonian, and helped to further understand the nature and the tectonic evolution of the Boshchekul-Chingiz island arc in the West Junggar.

关 键 词：赞岐岩 中志留世 板片熔体交代 俯冲带 西准噶尔 

分 类 号：P588.14[天文地球—岩石学]