黑龙江三矿沟-庄乎河地区岩浆岩年代学、地球化学研究及其俯冲构造与成矿意义

Geochronology and Geochemical Characteristics of Igneous Rocks in the Sankuanggou-Zhuanghuhe area in Heilongjiang and Its Implications for Subduction Structure and Metallogeny

黑龙江三矿沟-庄乎河地区位于多宝山成矿带北侧,区内构造-岩浆-热液活动复杂,主要发育有三矿沟矽卡岩型矿床及庄乎河热液脉型矿床。本文选择三矿沟-庄乎河地区的岩浆岩主体为对象开展年代学、岩石学及元素地球化学等综合研究,系统厘定两个时期的岩浆岩,包括海西期庄乎河流纹岩(288~294 Ma)、庄乎河花岗斑岩(297~303Ma),燕山期三矿沟花岗闪长岩(172~179Ma)和庄乎河矿区石英闪长岩(165~176Ma)。三矿沟-庄乎河地区的成(含)矿岩浆岩均具有高硅、高铝及富碱的I型花岗岩特征,富集Rb、Sr、Ba、K等大离子亲石元素,亏损Nb、Ta、Ti等高场强元素,轻重稀土元素分馏明显,δEu亏损等特征。本次研究认为研究区与成矿作用有关的构造背景为活动大陆边缘,三矿沟-庄乎河地区在海西期受到古亚洲洋俯冲作用形成庄乎河花岗斑岩及流纹岩,而燕山期三矿沟花岗闪长岩和庄乎河石英闪长岩则与成矿富集作用有关,且两区矿床成矿作用与燕山期古太平洋俯冲作用密切相关。

The Sankuanggou-Zhuanghuhe area is located in the north of the Duohaoshan metallogenic belt in Heilongjiang Province, NE China. Tectonic-magmatic-hydrothermal activities in the area are complicated, resulting in the formation of Sankuanggou skarn type deposits and Zhuanghuhe hydrothermal vein deposits. This study investigated geochronological, petrograpic and geochemical characteristics of magmatite rocks in the Sankuanggou and Zhuanghuhe areas. Two-period magmatic rocks have been identified： Hercynian rhyolite in Zhuanghuhe （288 Ma-294 Ma） and Hercynian Granite porphyry in Zhuanghuhe （297 Ma-303 Ma）, and Yanshanian granite in Sankuanggou （172- 179 Ma） and quartz diorite in Zhuanghuhe （165-176 Ma）. Ore-forming magmatic rocks in the Sankuangou-Zhuanghuhe area are high Si and Al, alkali-rich type-I granite, and enrichment of LILEs （such as Rb, Sr, Ba, and K）, and depletion of HSFEs （such as Nb, Ta, and Ti）, with distinct fractionation of HREE and LREE, and 3Eu loss. This study suggests that rhyolite and granite porphyry in Zhuanghuhe formed in active continental margin and was the result of subduction of the paleo Asian Ocean in the Hercynian period. The Yanshanian granite in Sankuanggou and quartz diorite in Zhuanghuhe are related to mineralization and enrichment, and the mineralization in the two areas was closely related to the subduction of the paleo Pacific in Yanshanian period.