藏南松多地区阿扎朗岩体LA-ICP-MS锆石U-Pb年龄和地球化学特征

阿扎朗岩体位于冈底斯岩浆弧中东部的松多地区.岩体的锆石U-Pb定年和全岩地球化学分析结果表明，阿扎朗岩体岩性为石英二长斑岩，形成时代为中新世（17.9±0.2 Ma），地球化学上表现高Sr（1 052×10-6~1 150×10-6）、低Y（8.51×10-6~9.04×10-6）和Yb（0.85×10-6~0.94×10-6），高的Sr/Y（118~128）和La/Yb（30.9~40.8）比值，无明显的Eu异常，同时具有较高的K₂O（3.17%~3.84%）含量和较低的Cr（6.46×10-6~7.78×10-6）和Ni（5.41×10-6~7.45×10-6）含量，较高的Rb/Sr比值，较高的Mg#值（43.8~49.8），大离子亲石元素的含量，如Rb、Ba、Th和U明显比LREE高.这些地球化学特征表明其岩石成因可能为增厚的下地壳部分熔融形成，形成于印度－欧亚大陆碰撞造山的后碰撞构造背景下，可能有一定的幔源物质参与.该研究为揭示冈底斯成矿带中新世埃达克岩的成因及成矿地质背景提供重要的制约. 

Geochemical Characteristics and LA-ICP-MS Zircon U-Pb Age of the Azhalang Intrusion in Sumdo,Southern Tibet

The Azhalang pluton is located in the Sumdo area in the east-central part of the Gangdise magmatic arc. Zircon U-Pb dating and geochemical analysis of the whole rock indicate that the Azhalang intrusion is quartz monzonite porphyry and the formation period is Miocene (17.9±0.2 Ma). Geochemical characteristics show high Sr (1 052×10-6-1 150×10-6), low Y (8.51×10-6-9.04×10-6) and Yb (0.85×10-6-0.94×10-6), high Sr/Y (118-128) and La/Yb (30.9-40.8) ratios, no obvious Eu anomalies, high K₂O (3.17%-3.84%) content, low Cr (6.46×10-6-7.78×10-6) and Ni (5.41×10-6-7.45×10-6) content, high Mg# value (43.8-49.8), high Rb/Sr ratio, large ion lithophile element content, such as Rb, Rb, Rb. Ba, Th and U were significantly higher than LREE.These geochemical characteristics indicate that the petrogenesis of the rocks may be formed by partial melting of the thicker lower crust and formed in the post-collisional tectonic setting of the India-Eurasia collision orogeny, and some mantle-derived materials may be involved.This study provides important constraints for revealing the genesis and metallogenic geological setting of the Miocene adakite in the Gangdise metallogenic belt.