摘要
研究区辉长闪长玢岩脉分布于石炭系提热艾力组中,锆石U-Pb定年结果表明,岩脉的形成年龄为(218±1)Ma,为早中生代印支期岩浆作用的产物。岩石ΣREE=136×10^(-6)~202×10^(-6),LREE=119×10^(-6)~186×10^(-6),HREE=15×10^(-6)~17×10^(-6),轻稀土元素分馏较明显,重稀土元素分馏不明显。岩石相对富集Rb、Ba、K、LREE等大离子亲石元素,亏损Nb、Ta和HREE等高场强元素。结合锆石定年结果及岩脉产出的区域地质背景,认为晚三叠世西昆仑地区已进入后碰撞阶段,辉长闪长玢岩脉是在岩石圈伸展环境下形成的产物,岩脉的锆石U-Pb年龄为其提供了时代依据。
The gabbroic dioritic porphyrite dyke is distributed in Tireaili Group of Carboniferous.The zircon U-Pb dating results indicate that the formation age of dyke is 218 ± 1 Ma,which is the outcome of magmatism in Early Mesozoic Indosinian.Its ΣREE = 136×10^（-6）~ 202×10^（-6）,LREE = 119×10^（-6）~ 186×10^（-6）,HREE = 15×10^（-6）~ 17×10^（-6）,the light rare earth elements fractionate obviously,while the heavy rare earth elements contrarily.Rb,Ba,K,LREE and other large ion lithophile element are rich in the rock,Nb,Ta,HREE and other high field-strength elements are depleted.According to the zircon dating results and local geological setting,Western Kunlun has entered to post-collision setting in late Triassic epoch.And the gabbroic dioritic porphyrite dyke is the outcome under the lithosphere extension environment,whose U-Pb dating age supplies the time-criterion for it.
出处
《资源环境与工程》
2017年第3期237-242,共6页
Resources Environment & Engineering
关键词
晚三叠世
岩脉
年代学
岩石地球化学
西昆仑
Late Triassic
dyke
geochronology
lithogeochemistry
western Kunlun
