黑龙江新开岭变质核杂岩的组成及其演化

新开岭变质核杂岩位于黑龙江省北部黑河地区,由断层下盘的变质核、拆离断层和上盘滑脱—冲断系所构成,地貌上呈长垣型的隆起带,变质核内面理外倾,盖层中褶皱轴向呈环形展布。本文根据同位素测年结果讨论了新开岭变质核杂岩的隆升和演化特征。中央侵入体花岗闪长岩的结晶年龄为171~164Ma,变质的白云母和流纹质糜棱岩的变形年龄分别为142Ma和155Ma,北部边界断裂带糜棱岩的⁴⁰Ar-³⁹Ar年龄为154.9±0.6Ma。中央侵入体的侵入时间代表了核杂岩的隆升时间,北部冲断带的年龄代表大规模的变形时间。岩浆流体、变质流体和构造流体的叠加使成矿更为有利,是今后找矿的重点地区。

COMPOSITION AND EVOLUTION OF THE XINKAILING METAMORPHIC CORE COMPLEXES IN HEILONGJIANG PROVINCE

The Xinkailing Metamorphic Core Complex exposed in Heihe area, northern part of Heilongjiang province. It was composed of the metamorphic core in the lower plate (metamorphic and granitic rocks),the detachment faults and the sedimentary cover in age of Sinian to Triassic in the upper plate. Geomorphologically, it was long dome-shaped in landform, with the inner planar joint of metamorphic core dipping towards outside, and the fold axes in the capping beds being circular distributing. Based on recent isotopic data, the paper discussed uplifting time and evolution of the Xinkailing Metamorphic Core Complexes. The granodiorite in the lower-plate intrusive body intruded 171～164 Ma ago, the deformation ages of muscovite and metamorphic rhyolitic were 142 Ma and 155 Ma respectively, and the ⁴⁰Ar-³⁹Ar age of the mylonite in northern boundary fault was 154.9±0.6 Ma, which indicated that the lower-plate intrusive body occurred in Middle Jurassic, and the metamorphic core complex uplifted in Late Jurassic. All strata of the metamorphic core complex were covered by the Upper Jurassic and Lower Cretaceous, which meant that it outcropped and eroded in late Late Jurassic. It should be an advantaged area for mineralization since admixture of magma liquid, metamorphose liquid and structure liquid, so it might become an area of reconnaissance mineral deposits.