新疆玛因鄂博断裂南侧阿热勒托别岩体地球化学特征及地质意义
Geochemistry and Tectonic Implications of the Aretuobie Pluton to South of the Mayinebo Suture Zone in Altay, Xinjiang
-
摘要: 阿热勒托别岩体位于玛因鄂博断裂南侧,由二长花岗岩组成,其岩石化学具有与A型花岗岩相似的高碱、低铝的特点,但与典型的A型花岗岩相比,其钙、镁含量偏高,硅略偏低.岩石稀土元素含量较高,ΣREE为227.04×10-6~326.42×10-6;轻稀土富集,轻、重稀土比值L/H为5.6~6.9,具有中等程度的铕负异常,δEu为0.4~0.6;岩石中不相容元素富集,具有Sr、Ba、Nb、P、Ti等元素负异常;全岩δ18O(SMOW)值分别为4.4‰和4.6‰;岩石具有较低的Sr初始比值和正的∈Nd值,分别为0.70048~0.70547和+2.6~+3.2,两阶段Nd模式年龄为0.91Ga和0.94Ga.地球化学特征表明其原始岩浆来自年轻的玄武质下地壳的重熔.阿热托别岩体为形成于后碰撞伸展背景下的I型花岗岩,具有某些与A型花岗岩相似的地球化学特征.Abstract: The Aretuobie monzonitic granite is located to the south side of the Mayinebo suture zone. It shares some characteristics of the A-type granite, such as high alkali and low alumina. However, comparing with typical A-type granite, it has relatively high MgO and CaO and low SiO2. In trace elements, their total REE ranges from 277 ppm to 326 ppm and the ratios of LREE/HREE are bet ween 5.6 and 6.9. Negative Eu anomalies (δEu=0.4-0.6) are present ed in the REE pat terns. The rocks are enriched in incompatible elements and havev ariable Sr, Ba, Nb, P and Ti troughs in their trace elements distribution patterns. Isot opically, they have low initial Sr ratios (0.70048-0.70547) and positive initial Nd values (2.6-3.2). Collectively, we suggest that the Aretuobie pluton was derived from partial melting of a juvenile maficlo wercrust in a postorogenic extensional background.
-
Key words:
- Aretuobie pluton /
- Geochemistry /
- post-collision
-
-
计量
- 文章访问数: 2305
- PDF下载数: 2867
- 施引文献: 0
下载: