【作者】 刘成东； 莫宣学； 罗照华； 喻学惠； 谌宏伟； 李述为； 赵欣；

【Author】 LIU Chengdong MO Xuanxue LUO Zhaohua YU Xuehui CHEN Hongwei LI Shuwei ZHAO Xin (China University of Geoscience, Beijing, 100083; East China Institute of Technology, 344000)

【机构】 中国地质大学；

【摘要】 本文报道了东昆仑造山带三叠世辉长岩、花岗岩类及其中包体的Pb、Sr、Nd和O同位素组成。东昆仑造山带花岗质岩石全岩和长石Pb同位素组成相差不大,具明显的造山带Pb同位素特征;Sr同位素初始值I_Sr变化于0.70144～0.70972之间,暗示幔源成因;εNd值变化于-4.49939～-9.19258之间,具壳源成因特点;Nd同位素模式年龄(T_DM在1.38～1.761Ga之间,与中元古变质岩相当;O同位素组成变化范围7.8～9.5,也表明花岗岩类成岩物质主要来自地壳。综合岩石的同位素组成,结合矿物学、岩石地球化学的研究,表明花岗岩浆主要起源于地壳,但与来自地幔的基性岩浆曾发生过混合作用,从而导致同位素组成趋于一致。更多还原

【Abstract】 This paper reports Pb, Sr, Nd and 0 isotopic compositions of the gabbro, granitoids which were formed in the Triassic epoch in Eastern Kunlun orogenic belt. Pb isotopic compositions of granitoids and potassic feldspar are similar.The results indicate that they are formed in orogenic environment. Initial(87Sr/86Sr)t ratios range from 0.7014 to 0.70972, and t Nd values from -4.49939 to -9.19258, and Nd isotopic modle ages (TDM) from 1.38Ga tol.761Ga, being close to the age of mesoproterozoic epoch metamorphic rocks.O isotopic compositions range from 7.8 to 9.5, and they indicate that the granitoids are derived from the crust. Therefore, the granitoids are mainly derived from the crust and mixed by the mantle-derived materials on the basis of all isotope data and the study on mineralogy and petrochemistry. The mixing process between the crust materials and mantle-derived materials causes the compositions of isotope tend to be the same.更多还原