论文部分内容阅读
黑河新生地区位于大、小兴安岭的结合部,其早白垩世岩浆活动频繁,主要岩石类型为花岗斑岩、花岗闪长岩。地球化学特征显示这些岩石为高钾钙碱性系列的I型花岗岩,富集大离子亲石元素(LILE)而亏损高场强元素(HFSE)。LA--ICPMS锆石U--Pb年龄测定结果表明,花岗斑岩的形成时代为118.1±1.5 Ma,花岗闪长岩的形成时代为112.8±0.9 Ma,这与该区广泛分布的早白垩世火山岩形成时代一致。Hf同位素成分特征表明,岩体的源岩为中—新元古代时期由亏损地幔起源的火成岩。结合岩石学特征和邻区其他地质资料,认为黑河新生地区早白垩世花岗岩的形成与古太平洋板块的俯冲作用有关。
The Heihe Xinsheng area is located at the junction of the Greater and Xiaoxing’an Mountains. Its Early Cretaceous magmatic activity was frequent with the main rock types being granite porphyry and granodiorite. Geochemical characteristics indicate that these rocks are high-K calc-alkaline series I-type granites that enrich large ion lithophile elements (LILEs) and loss high-field elements (HFSEs). LA - ICPMS zircon U - Pb ages show that the age of granite porphyry is 118.1 ± 1.5 Ma and the age of granodiorite is 112.8 ± 0.9 Ma, which is consistent with the widely distributed early Cretaceous volcanic rocks formed in the same era. The Hf isotopic compositions indicate that the source rocks of the rock mass are igneous rocks originated from the depleted mantle during the Meso-Neoproterozoic. Combined with petrological characteristics and other geological data in the adjacent area, it is considered that the formation of Early Cretaceous granites in the Heihe Xinsheng area is related to the subduction of the Paleo-Pacific plate.