内蒙古巴林右旗胡都格绍荣岩体的年代学、地球化学、Hf同位素特征及构造背景

大兴安岭地区晚中生代的大地构造背景一直存在争议，通过对内蒙古巴林右旗胡都格绍荣岩体进行锆石U-Pb测年、岩石地球化学以及锆石Lu-Hf同位素分析，探讨其形成时代及构造背景.胡都格绍荣岩体主体岩性为似斑状黑云母二长花岗岩，LA-ICP-MS锆石U-Pb测年确定其加权平均年龄为129.9±1.4 Ma(MSWD=0.91)，指示其侵位于早白垩世.花岗岩具有高SiO₂、Na₂O、K₂O含量，低CaO、MgO含量，富集Cs、Rb、K、Th、U、Zr，亏损Ba、Sr、P、Ti，轻稀土富集，具明显Eu负异常(δEu=0.35~0.44)，10 000×w(Ga)/w(Al)]为2.08~3.05，表明其为典型的A型花岗岩.Hf同位素分析结果显示，锆石具有正的ε_Hf(t)值(2.24~9.41)，Hf两阶段模式年龄为1 030~570 Ma，平均为809 Ma，结合其微量元素特征，认为岩浆来源于新元古代地壳的部分熔融.胡都格绍荣花岗岩指示研究区在早白垩世为伸展构造背景，可能与蒙古-鄂霍茨克洋闭合关系更为密切. 

Geochronology,Geochemistry, Zircon Hf Isotopic Characteristics and Tectonic Setting of Hudugeshaorong Pluton in Balinyouqi,Inner Mongolia

The tectonic setting of Da Hinggan Mountains area at the Late Mesozoic has always been controversial, this paper presents zircon U-Pb age, geochemistry and Hf isotopic data of Hudugeshaorong pluton in order to discuss its formation time and tectonic background. Hudugeshaorong pluton is mainly composed of porphyritic biotite monzogranite with LA-ICP-MS zircon U-Pb age of 129.9±1.4 Ma (MSWD=0.91), indicating it was intruded at the Early Cretaceous. This granite pluton is high in SiO₂, Na₂O, K₂O and low in CaO, MgO, enriched in Rb, K, Th, U and Zr, and depleted in Ba, Sr, P and Ti. Rare earth elements show light REE enrichment (LREE/HREE=6.90-9.39) with obvious negative Eu anomalies (δEu=0.35-0.44), the ratio of 10 000×w(Ga)/w(Al)] is between 2.08 and 3.05, showing that it is typical A-type granite. Hf isotopic analysis results show a positive ε_Hf(t) values (2.24-9.41), two-stage model ages ranging from 1 030 Ma to 570 Ma, with an average age of 809 Ma. Combining with Th/U and Nb/Ta, we suggest that the primary magma was derived from the partial melting of the Neoproterozoic crust. Hudugeshaorong granite indicates that the study area was in an extensional environment during the Early Cretaceous, we suggest it is more likely related to the closure of the Mongol-Okhotsk Ocean.