西藏措勤赤马地区古近系年波组火山岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及其成因

发布时间：2018-07-09 14:55

本文选题：年波组火山岩 + 地球化学　；参考：《地质论评》2017年04期

【摘要】：西藏措勤县赤马地区年波组火山岩大地构造位置位于隆格尔—工布江达复合岛弧带,岩石w(SiO_2)=72.46%~81.4%;w(Al_2O_3)=11.39%~12.72%;Alk(K_2O+Na_2O)=3.33%~8.5%;w(K_2O)/w(Na_2O)=1.09~46.68;A/CNK=1.4~3.4;里特曼δ=0.27~2.15,属过铝质的钾质、超钾质钙碱性—亚碱性的中酸性火山岩。稀土总量ΣREE=118.38×10~(-6)~343.65×10~(-6);LREE/HREE=2.13~10.99;δEu=0.07~0.38,轻稀土富集,重稀土亏损,配分曲线呈右倾型,较明显的铕负异常。富集K、Rb、LREE等大离子亲石元素,而亏损Nb、P、Ti等高场强元素的特征,岩石显示出岛弧火山岩相似特征。锆石U-Pb定年结果显示,年波组火山岩成岩年龄约65~45Ma间,为古新世—始新世。年波组火山岩显示出物质来源主要为地壳物质重熔和地幔物质同化混染,由老到新,地壳物质贡献增强。
[Abstract]:The tectonic position of the volcanic rocks of the Nimbo formation in Chima area, Toqin County, Tibet is located in the Longgie-Gongbujiangda complex island arc belt, rock w (SiO2) 72.4646and 81.4 + 81.4. (Al2O3). It is 11.3939, and has 12.72Alk (K2O Na2O) 3.338.5w / w (Na2O) / w (Na2O), 1.0946.68A / CNK = 1.43.4; the Richter 未 0.272.15 belongs to the over-aluminous potassium, super-potassium calc-alkaline-subalkaline intermediate acid volcanic rocks. The total amount of REE is 118.38 脳 10 ~ (-6) O ~ (343.65) 脳 10 ~ (-6) ~ (-6) LREE / HREE ~ (2 +) 2.13 ~ (13) ~ (10.99), 未 EU ~ (0.07) O _ (0.38), which is enriched in light rare earths, depleted in heavy rare earths, and the partition curve is right-tilted, with obvious negative europium anomaly. The characteristics of enrichment of large ion lithophile elements, such as K RbSe, LREE, and depletion of high field strength elements, such as NbPU Ti, show that the rocks show similar characteristics of island arc volcanic rocks. The zircon U-Pb dating results show that the diagenetic age of the volcanic rocks in the Nimbo formation is about 6545 Ma, which is from Paleocene to Eocene. The volcanic rocks of the Nianbo formation show that the material sources are mainly crustal material remelting and mantle material assimilation, and from old to new, the crustal material contribution is enhanced.
【作者单位】：成都理工大学地球科学学院;四川省地质矿产勘查开发局攀西地质队;达州市安全生产监督管理局;广西壮族自治区遥感中心;
【基金】：中国地质调查局地质调查项目(项目编码:DD20160015;1212011221067)的成果~~
【分类号】：P588.14;P597.3

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