【摘要】 大加山碱性花岗岩位于卡拉美丽-哈尔里克花岗岩带的中段,主要为中细粒钠铁闪石花岗岩。大加山碱性花岗岩锆石LA-ICPMS年龄为284±1Ma。该花岗岩具有富碱（A/CNK<1,AR=3.9～6.67）和具有高的FeO^T/MgO和10000×Ga/Al值,而钙和铝含量较低的特征,相对富集稀土元素REE（除Eu）元素、大离子亲石元素（Rb、U、Th、K）,而强烈亏损Ba、Sr、P、Ti、Eu元素的特征。同时其Y/Nb（2.71～3.75）>1.2。这些说明大加山岩体为二叠纪A₂型花岗岩。东准噶尔和天山地区各花岗岩带年龄有向南为逐渐年轻的趋势,这与新疆北部由北向南增生的方向一致。因此,可能是侧向增生与垂向增生均表现出向南增生极性。更多还原

【Abstract】 The Dajiashan alkali granite is situated at the central parts of the Kalameili-Haerlike granitic belt of Eastern Junggar, Northwest China.LA-ICPMS zircon U-Pb dating shows that its crystallization age is 284±1Ma.The Dajiashan alkali granite is characterized by high absolute SiO₂,Alkali（A/CNK<1,AR=3.9～6.67）abundance,low CaO and Al₂O₃;high FeO_T/MgO and 10000 * Ga/Al ratios;enriched REE（except Eu）,LILE（Rb,U,Th,K）and some HFSE（Zr,Hf,Nb,Ta）;strongly depleted Ba, Sr P,Ti,Eu;Y/Nb（2.71～3.75）>1.2.All these facts reveal that the Dajiashan alkali granite is a Permian A₂-type granite.The distribution of ages of the other A-type and late-orogenic granites belts in the Eastern Junggar area indicates a south-ward younging trend,which is good agreement with the south-ward accretion.更多还原