内蒙古哈多河-阿尔本格勒地区花岗岩年代学及其地质意义

CHRONOLOGY AND ITS GEOLOGICAL IMPLICATION OF THE GRANITES IN HADUOHE-AERBENGELE AREA,INNER MONGOLIA

对哈多河-阿尔本格勒地区二叠纪花岗岩进行年代学研究,获得花岗岩、花岗斑岩锆石U-Pb SHRIMP年龄分别为133.2±1.7 Ma和127.0±2.0Ma,为早白垩世.岩石化学研究表明,花岗岩、花岗斑岩均为钙碱性岩石,为S型花岗岩.岩石稀土元素分馏较为彻底,无明显的铕异常,与区域内典型二叠纪花岗岩(SI型)没有明显区别,表明在燕山晚期该地区具有碰撞造山晚期的复杂构造背景,暗示自华力西期至燕山晚期经历了多期次的碰撞造山作用,岩浆活动与古亚洲洋构造域转换、叠加滨太平洋构造域有关.

Geochronogic study on the previously decided Permian granites in Haduohe-Aerbengele area, Inner Mongolia obtains the U-Pb SHRIMP zircon ages of 133.2±1.7 Ma and 127.0±2.0 Ma for granite and granite-porphyry, respectively, suggesting a Cretaceous age. The lithogeochemical study shows that both the granite and granite-porphyry are cale-alkaline, belonging to S-type granite. The rare earth elements are well fractionated, without significant Eu anomaly. The rocks present no evident differences to the typical granite （SI-type） in the region, showing a complex tectonic setting of late collision- orogeny during Late Yanshanian stage. Multiple collision-orogeny movements took place from Variscan to Late Yanshanian in the region. The magmatic activities are related to the transition of Paleo-Asia tectonic domain and the superposition of marginal-Pacific tectonic domain.