中文摘要：

小秦岭碳酸岩位于华北板块南缘,其（87Sr/86Sr）i与εNd值分别介于0.70495～0.70552和-10.1～4.6之间,紧靠EM1地幔端元,但相对EM1具有低Sr和低Nd特征。Pb同位素与华北板块南缘完全不同,而是落在了南秦岭下地壳范围之内,这表明华北板块南缘下地壳或地幔已经受到南秦岭地壳物质俯冲置换的影响,即在晚三叠纪时期,秦岭地区的碰撞造山作用可能已经结束,转入伸展拉张的构造环境。并进一步论述了秦岭地区三叠纪花岗岩是在深部拉张的构造环境下形成以及具有幔源物质参与的特征。

英文摘要：

The Lesser Qinling carbonatite is located at the southern margin of North China craton.The Sr,Nd isotopic characteristics are close to the EM1 mantle member [（87Sr/86Sr）i =0.70495～0.70552;εNd =-10.1～4.6],but with low Sr and Nd compared to EM1.The Pb isotopic characteristics of the carbonate rocks are in the range of southern Qinling Mountains,completely different from the North China plate.This implies that the lower crust or mantle of the southern margin of the North China Craton has been mixed with the lower crust of South Qinling.So the carbonatites formed at the stage of extension after collision in the Qinling orogeric belt.This paper also argues that the Triassic granitoids formed under an extension background and were involved in mantle materials from Qinling Orogenic belt.