中文摘要：

对中冈底斯带北部申扎县买巴地区广泛分布于石炭—二叠纪地层中的中、酸性侵入岩进行了研究,获得其中的花岗岩和石英二长岩LA-ICP-MS锆石U-Pb年龄值分别为（110.8±0.9）Ma和（111.0±1.1）Ma,二者在误差范围内一致,表明其应该为同一期岩浆活动的产物.其总的地球化学特征是SiO2含量较高,而且均为铝质过饱和（A/CNK=1.05～1.38）,并且富集Al、Th、LREE等元素,其中Th丰度为14.8× 10-6～ 28.4× 10-6,暗示它们很可能与中上地壳物质有关;与上部陆壳及中冈底斯带110 Ma时地壳物质发生脱水重熔形成的则弄群酸性火山岩具有非常相似的蛛网图曲线,表明其可能为地壳物质脱水发生重熔有关.结合冈底斯带中北部地区广泛分布130～ 110 Ma则弄群、多尼组等火山岩分析,认为西藏申扎县买巴地区早白垩世110 Ma左右中、酸性侵入岩是班公湖—怒江洋盆南向俯冲消减的产物.

英文摘要：

In this paper, the authors studied the intrusive rocks widely distributed in Carboniferous - Permian strata in Maiba area of Xainza County within northern Middle Gangdise belt, and obtained the LA-ICP-MS zircon U-Pb age of 110.8±0.9 Ma for granite and age of 1 11.0±1.1 Ma for quartz monzonite, respectively. Both ages are consistent within the error range, suggesting that the granite and the quartz monzonite should he the product of the same magmatic activity. The intrusive rocks are characterized by high SiO2, supersaturated aluminum （A/CNK=l.05-1.38）, and enrichment of A1, Th, LREE, with Th abundance being 14.8 ×10^-6-28.4× 10^-6, implying that they are probably associated with the upper crust substances. Their cobweb curve is remarkably similar to that of the upper crust and acidic volcanic rocks resulting from crustal remelting of 110 Ma Zenong Group in Middle Gangdise belt. These data indicate that the intrusive rocks might be the remelting products caused by the dehydration of crustal materials.