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火山岩岩石化学研究表明 ,西昆仑山东段北缘石炭纪火山岩的SiO2 含量在 42 .98%～ 5 0 .78%之间 ,Na2 O +K2 O在 1.5 2 %～ 5 .85 %之间 ,Na2 O/K2 O为 1.5 3～ 5 .86 ,显示出明显的富钠特征。稀土元素特征为 :ΣREE为 (146 .91～ 472 .14)× 10 -6,LREE/HREE为 1.78～ 2 .5 8,δEu为 1.0 4～ 1.15 ,(La/Yb) N 为 3.45～ 5 .32 ,球粒陨石标准化曲线为右倾的弱铕正异常的轻稀土富集型的平滑曲线。微量元素研究结果 :Nb/Ta比值在 15 .96～ 17.99之间 ,Zr/Hf比值在37.2 2～ 41.42之间 ,相对富集大离子亲石元素 (LIL)和高场强元素 (HFS) ,在微量元素N -MORB配分模式图上 ,呈明显的左侧单“隆起”型 ,即大离子亲石元素 (LIL)呈现峰值。Rb -Sr同位素组成研究结果表明 :样品Rb/Sr比值在 0 .0 0 49～ 0 .1314之间 ,表明岩浆在上升过程中受到了地壳物质的混染。综合分析认为 ,该区火山岩具有板内玄武岩的特征 ,应属产于大陆边缘弧后盆地的钠质碱性玄武岩
Volcanic rock petrochemical studies show that the Carboniferous volcanic rocks in the northern margin of the eastern section of the western Kunlun Mountains have SiO2 contents between 42.98% and 50.78%, Na2 O + K2 O between 1.52% and 5.85%, Na2 O / K2 O was 1.53 ~ 5 .86, showing a clear sodium-rich character. The characteristics of REE are as follows: ΣREE is (146.91 ~ 472.14) × 10 -6, LREE / HREE is 1.78 ~ 2.58, δEu is 1.0 4 ~ 1.15, (La / Yb) N is 3.45 ~ 5. 32, chondrite normalized curve for the rightward weak europium positive anomalous light rare earth-rich smooth curve. The results of trace elements study showed that Nb / Ta ratios were between 15.96 and 17.99 and Zr / Hf ratios were between 37.22 and 41.42, which were relatively enriched in LIL and HFS. On the pattern of micronutrient N -MORB partitioning pattern, there is an obvious single “uplift” type on the left side, that is, the peak of large ion lithophile (LIL) appears. The results of Rb-Sr isotope composition indicate that the Rb / Sr ratio of the samples is between 0.049 and 0.1314, indicating that the magma was contaminated by the crustal material during the rising process. The comprehensive analysis shows that the volcanic rocks in this area have the characteristics of intraplate basalts and should belong to the alkaline basalts of sodium basalts