对大兴安岭中部柴河林场地区钾长花岗岩进行了系统的地球化学及锆石U-Pb同位素年代学研究,并对其岩石成因及构造意义进行讨论.研究结果表明,柴河林场地区钾长花岗岩中锆石具有典型的岩浆振荡生长环带和较高的Th/U比值(0.44 ～ 1.42),反映了岩浆成因特征.LA-ICP-MS锆石U-Pb定年结果为133±3Ma.岩石具有富硅、稀土元素含量较高、相对富集轻稀土元素亏损重稀土元素的特征,Eu负异常较为明显,稀土元素配分图解具有右斜“V”字型的特征,并相对富集高场强元素和大离子亲石元素.以上特征表明,柴河林场地区钾长花岗岩为铝质A型花岗岩,是地壳岩石部分熔融的产物,具有典型A1型(裂谷或板内)花岗岩的特征,代表了伸展的构造环境.%In this paper, the geochemistry and zircon U-Pb isotope chronology of the Chaihe K-feldspar granites in the central Greater Xing'an Range is studied and their petrogenesis and tectonic significance are discussed. The zircons from Chaihe K-feldspar granites show oscillatory growth zonations of typical magmatic origin and high Th/U ratios (0. 52 ~ 1. 33) , indicating a magmatic origin for the zircons, and yielded a LA-ICP-MS U-Pb age of 133 ±3Ma. The granites have high SiO2 rare earth elements ( REE) , high field-strength elements (HFSE) , and large ion lithophile elements (LILE) contents. The REE patterns are characterized by enrichment of LREEs relative to HREEs and distinct negative Eu anomalies in chondrite-normalized REE diagram, which is characterized by right oblique and "V"-shaped feature. These features suggest that the Chaihe K-feldspar granites belong to aluminous A-type granite which derived from partial melting of crustal rocks with a typical character of A,-type ( rift valley or within plate) granite representing an extensional tectonic environment.
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