东北地区是中国显生宙花岗岩极其发育的地区，构造演化复杂。研究大兴安岭东北部塔河地区早白垩世侵入岩是解决大兴安岭地区中生代岩浆演化及构造背景的重要突破口。塔河地区早白垩世侵入岩的岩性主要有石英闪长岩、花岗闪长岩、二长花岗岩、正长花岗岩和花岗闪长斑岩。运用LA-ICP-MS测年方法对花岗闪长岩和石英闪长岩进行测年，锆石U-Pb年龄分别为131±1Ma(MSWD=0．73)和130±1Ma(MSWD=2．2)。早白垩世侵入岩SiO2含量为61．32%~71．68%，为中酸性岩类。 Al2 O3含量为13．53%~15．62%，显示为准铝质或过铝质、高钾钙碱性花岗岩。∑REE为(152．28~253．85)×10-6。地球化学特征可分为高Sr低Yb型和低Sr高Yb型两类侵入岩，起源于地壳的不同深度。研究区早白垩世侵入岩形成于蒙古-鄂霍次克洋洋盆自西向东的剪切式收缩闭合作用，可能与蒙古-鄂霍次克造山带陆-陆碰撞导致下地壳加厚作用有关。%The Phanerozoic granites occur on a wide range of scales in northeastern China. The emphasis in this study is placed on the Early Cretaceous intrusive rocks from the Tahe region, NE Dahingganling region, where the research of the intrusive rocks may be highly helpful to the understanding of Mesozoic magmatic evolution and tectonic settings. The intrusive rocks in this region consist dominantly of quartz diorite, granodiorite, monzogranite, syenogranite and granodioritic porphyry. The LA-ICP-MS zircon U-Pb dating yields the age determinations of 131 ± 1 Ma (MSWD=0. 73) and 130 ± 1 Ma (MSWD =2. 2) for granodiorite and quartz diorite, respectively. The intrusive rocks cited above are enriched in SiO2(61. 32% -71. 68%) and Al2O3(13. 53% -15. 62%), and have the ΣREE values between 152 . 28 × 10-6 and 253 . 85 × 10-6 , indicating the metaluminous or peraluminous high-K calc-alkaline granitic rocks. Geochemically, these granitic rocks may be classified into two types:high-Sr and low-Yb, and low-Sr and high-Yb types originated from different depths of the Earth’ s crust. It is inferred that the Early Cretaceous intrusive rocks in the study area were created by the processes of gradually eastward shear closure of the Mongolia-Ochotsk Sea basin, and probably related to the thickening of the lower crust caused by the continent-continent collision along the Mongolia-Ochotsk orogenic belt.
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