论文部分内容阅读
甘肃天水地区黄门川花岗闪长岩体位于北祁连造山带东端,侵位于晚奥陶世陈家河群中酸性火山岩系中,岩石学和地球化学特征表明其具有壳幔岩浆混合的特点。对黄门川花岗闪长岩体进行了LA-ICP-MS锆石U-Pb定年,结果表明该花岗闪长岩体的年龄为440.5Ma±4.4Ma,形成于早志留世。地球化学特征表明,黄门川花岗闪长岩体属于中钾钙碱性系列,具I型花岗岩的特征。构造环境判别表明其形成于安第斯型大陆边缘弧。综合区域地质背景,认为祁连造山带东端在早古生代期间发育有有限洋盆,洋盆向北俯冲消减产生大量弧岩浆岩。对进一步研究祁连与秦岭造山带构造交接部位早古生代的构造格局、演化等大陆动力学问题具有重要意义。
The Huangmenchuan granodiorite body in the Tianshui area of Gansu is located at the eastern end of the North Qilian orogenic belt and intruded into the acidic volcanic rocks of the Chenjiahe Group in the Late Ordovician. The petrological and geochemical characteristics of the Huangmenchuan granodiorite show that it has the characteristics of crust-mantle magmatic mixing . LA-ICP-MS zircon U-Pb dating of the Huangmenchuan granodiorite body was performed. The results show that the age of the granodiorite body is 440.5Ma ± 4.4Ma, formed in the Early Silurian. Geochemical characteristics indicate that the Huang-Men-Chuan granodiorite belongs to the medium-K calc-alkaline series with the characteristics of I-type granite. Tectonic environment discrimination shows that it formed in the Andean continental margin arc. Based on the regional geological background, it is considered that the eastern end of the Qilian orogenic belt developed a finite oceanic basin during the Early Paleozoic, and the subduction of the oceanic basin to the north resulted in a large amount of arc magmatic rocks. It is of great significance to further study the continental dynamics of the tectonic framework and evolution of the Early Paleozoic in the Qilian-Qinling orogenic belt.