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小兴安岭北麓石林公园区钼钨矿化点是近年笔者所在团队在该区新发现的。在矿床地质特征研究的基础上,开展了矿石矿物辉钼矿的Re-Os同位素定年和锆石LA-ICP-MS U-Pb定年及赋矿围岩花岗岩的元素地球化学研究。碱长花岗岩加权平均年龄为(207±3.1)Ma,辉钼矿的Re-Os同位素加权平均年龄为(207.55±3.4)Ma。初步厘定该矿化发生在207 Ma左右,成岩成矿发生在印支晚期。花岗岩以高硅(w(SiO2)大于75%)、富碱(w(Na2O+K2O)为1.78%～8.58%)、低钙(w(CaO)小于0.3%)及高FeOT/MgO值(平均25.75%)为特征,并具有强Eu和不同程度的Ba、Sr、P和Ti等元素亏损,具有高分异A型花岗岩的成因属性。这一成果揭示了该区钼钨矿化与高分异A型花岗岩密切相关,是佳木斯板块和松嫩—张广才岭板块在印支晚期碰撞造山后伸展阶段花岗岩浆强烈分异作用的产物。
Xiaoxinganling northern foot of Shilin Park Molybdenum tungsten mineralization point in recent years, the author team where the new discovery. Based on the study of the geological characteristics of the deposit, the Re-Os isotopic dating of ore minerals molybdenite and the zircon LA-ICP-MS U-Pb dating and the element geochemistry of the ore-bearing granite are carried out. The weighted average age of alkali-bearing granites is (207 ± 3.1) Ma, and the Re-Os isotopic weighted age of molybdenite is (207.55 ± 3.4) Ma. Preliminary determination of the mineralization occurred in about 207 Ma, diagenetic mineralization occurred in the late Indosinian. The content of high-FeOT / MgO (average CaO) and high FeOT / MgO (average CaO content) 25.75%), with strong Eu and varying degrees of depletion of Ba, Sr, P and Ti, with the genesis property of highly-differentiated A-type granites. This result reveals that molybdenum and tungsten mineralization in this area is closely related to high-grade A-type granites, and is a product of the strong differentiation of the granitic magmas in the extensional stage of the Late Indo-Chinese uplift of the Jiamusi and Zhangnenageonic plates.