�Դ��˰����ж������������������������ʯ�������ʯU-Pb���ѧ��Lu-Hfͬλ�غ�ȫ�ҵ���ѧ�о����ʯU-Pb��������ʾ����������������������ʯ�γ���134~127 Ma��Ϊ��������ҽ���IJ���ڵ���ѧ�����ϣ���Щ��������ʯ�ձ���и߹裨SiO₂=65.21%~78.43%�������K₂O+Na₂O=6.77%~9.66%����ƶCaO��0.10%~2.55%����MgO��0.07%~1.30%��������������Rb��Th��U�ȴ�������ʯԪ�أ�����Nb��Ta��Ti��P�ȸ߳�ǿԪ�أ����ڸ߼ظƼ���I�ͻ�������ʯ���ʯε_Hf��t��=+4.9~+8.4��t_DM2=654~874 Ma��������Դ����Ԫ�Ŵ��ڼ��������ĵؿ����ʵIJ������ڣ���������о����ϣ���Ϊ�˰����ж����������������������ҵ��γ����̫ƽ����ĸ������ù�ϵ���С�

The authors studied the zircon U-Pb geochronogy,Lu-Hf isotopic compositions and whole-rock major and trace element data for Late Mesozoic granitiods in the Wuchagou area of the central Great Xing'an Range, NE China. The zircon U-Pb dating shows that the granitiods were formed in Early Cretaceous, ranging from 134 to 127 Ma in age. Geochemically, the granitiods are characterized by high silica (SiO₂=65.21%~78.43%) and total alkali concentrations (K₂O+Na₂O=6.77%~9.66%),but low concentrations of CaO (0.10%~2.55%) and MgO(0.07%~1.30%). They are also enriched in large-ion lithophile elements (e.g. Rb, Th, U) and depleted in high field elements (e.g. Nb, Ta, Ti, and P), indicating that they can genetically be ascribed to high-K calc-alkaline I-type granites. The positive ε_Hf(t) values (+4.9 to +8.4) of the Early Cretaceous granites and their corresponding Hf two-stage model ages of 654 Ma to 874 Ma indicate that the parental magma was derived from partial melting of Neoproterozioc juvenile crustal material. Combining with the regional research data, the authors considered that the formation of Early Cretaceous granites in the Wuchagou area was related to the subduction of Paleo-Pacific plate.

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