伊春前进地区岩浆岩的地球化学特征及其对成矿的制约

伊春前进地区地处伊春延寿成矿带中部,区内Mo、Cu、Pb、Zn、Ag等多金属矿产资源丰富,且成矿与岩浆活动关系密切。研究区出露的岩浆岩主要为花岗岩、二长花岗岩、正长花岗岩和酸性火山岩,岩石化学成分上以富铝钾、贫镁铁,且经历了较大的分离结晶作用为特征。岩石轻重稀土分馏明显,轻稀土富集,有明显的负铕异常。研究表明,前进地区岩浆岩为造山后阶段岩石圈伸展体制下导致地壳碱性至高钾钙碱性地壳岩石重熔的产物。通过对研究区岩浆岩成因、构造环境和成矿作用的讨论,确认该区多金属矿床的形成主要受岩浆活动的制约。

Magmatite Geochemical Characteristics and Their Constraints on Mineralizations in Qianjin Area,Yichun

The Qianjin magmatite in the Yichun area is located in the central part of the Yichun-Yanshou metallogenic belt which is rich in polymetallic mineral resources of Mo,Cu,Pb,Zn,Ag.The magmatite in the area consist mainly of granite,monzonitic granite,syenogranite and acid volcanics.Petrtochemically,the igneous rocks in the magmatite are characterized by enrichment in alkaline,potassium and aluminium,poor Mg and Fe,suggesting remarkable crystal differentiation.With rather high REE and LREE contents,obviously depleted in Eu,it is suggested that this late Mesozoic magmatite in the Qianjin area was formed at post-orogenic stage of rapid lithospheric extension by resultative remelting of calc-alkaline and high-K cal-alkaline crustal rocks.Furthermore,the genesis, structure and mineralization of the Qianjin magmatite are discussed.It is suggested that the formation of the polymetallic deposits in the area might have been controlled by the magmatic activities in the area.