| 赵明福,杨秦昆,安朝,魏有宁,吉明甲,韩建军,任鑫.青海大干沟西早三叠世二长花岗岩地球化学特征及其形成环境[J].矿产勘查,2019,(1):1-7 |
| 青海大干沟西早三叠世二长花岗岩地球化学特征及其形成环境 |
| The Geochemical characteristics and formed Environment of Early Triassic Monzonitic Granites from Northern Dagangou Area in Qinghai |
| 投稿时间：2018-05-17 |
| DOI： |
| 中文关键词: 二长花岗岩 早三叠世 地球化学特征 构造环境 大干沟西 |
| 英文关键词: Monzonitic granite,early triassic epoch,geochemical characteristics,tectonic environment Western Dagangou |
| 基金项目:青海省地质勘查基金项目(编号:2016020021jc021)资助。 |
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| 摘要点击次数: 2085 |
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| 中文摘要: |
| 青海省东昆仑地区大干沟西一带出露的侵入岩的岩石组合为中细粒花岗闪长岩—二长花岗岩—正长花岗岩等。通过对二长花岗岩的分析研究发现,SiO2含量为71.11%～77.07%；Al2O3含量为12.21%～14.38%；CaO含量为0.54%～2.45%、Na2O含量为2.80%～3.71%、K2O含量为3.59%～5.26%,里特x'z曼指数σ为1.55～2.14,为过铝质—高钾钙碱性系列花岗岩；稀土总量(ΣREE)为76.62×10-6～178.09×10-6,轻重稀土比(LREE/HREE)为4.35～13.54,δEu在0.27～0.78之间；微量元素中Sr、P、Ti等元素表现出明显的负异常,而Rb、Th、Ce、Nd等元素相对富集。在二长花岗岩中获得LA-ICP-MS锆石206Pb/238U年龄为(248.7±1.6 )Ma,显示时代为早三叠世。通过构造环境分析,大干沟西一带分布的早三叠世二长花岗岩即形成于板块碰撞前俯冲、挤压的构造环境。 |
| 英文摘要: |
| The concentrated distribution of intrusive rocks in Western Dagangou of Qinghai province which the combination of fine grained granodiorite-monzonitic granite-syenite,etc.Through the analysis of the monzonitic granite,show that(SiO2 between 71.11% and 77.07%,Al2O3 between 12.21% and 14.38%,CaO from 0.54% to 2.45%,Na2O between 2.80% and 3.71%,K2O between 3.59% and 5.26%,σ from 1.55 to 2.14).It is a series of granite with high potassium-calcium alkalinity.∑REE is 76.62-178.09×10-6,LREE/HREE is 4.35-13.54,the value of δEu is from0.27 to 0.78. Sr、P、Ti show a strong negative abnormality,Rb、Th、Ce、Nd show relativity enriched in the trace element characteristics.The age of the LA-ICP-MS zircon 206Pb/238U was 248.7±1.6 Ma,during the early triassic epoch.By constructing environmental analysis,it is believed that the monzonitic granite in the western Dagangou during early triassic epoch is formed in subducted and squeezing constructing environment before plate collision. |
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