金川县独松岩体锆石U-Pb年龄及其地球化学特征

Zircon U-Pb Age and Geochemical Characteristics of the Dusong Intrusion in Jinchuan

首次获得四川金川县南部的独松岩体锆石U-Pb年龄为200.9±4.3Ma。该岩体属钙碱性系列,富硅、低镁铁、富铝、富钾钠,K_2O较Na_2O偏高,富集大离子亲石元素K、Rb,贫Ba、Sr,高场强元素富等,贫Ta、Nb、Ti、P、Nb、Ta。稀土元素低-中等,轻稀土元素富集,重稀土元素相对亏损,轻重稀土分馏较明显。具弱的负铕异常,无明显的铈异常,具有基本一致的配分模式特征。独松岩体岩石类型为S型花岗岩,在Barbarin的划分方案中属于富钾钙碱性花岗岩类(KCG)。可能形成于造山阶段后碰撞环境。

The Dusong intrusion in Jinchuan belongs to calc-alkaline series with a zircon U-Pb age of 200.9 ±4.3Ma. The rock is characterized by enrichment in Si, A1, K, Na, Rb and HFSE and depletion in Mg, Fe, Ba, Sr, Ta, Nb, Ti, P. The REE geochemistry of the rock is characterized by enrichment in LREE and depletion in HREE with weak negative Eu anomaly and without obvious Ce anomaly. The intrusion belongs to S-type granitoid and rich-K calc-alkaline granitoid （ KCG ） of Barbarin. The intrusion should be emplaced in postorogenic collision setting.