小兴安岭—张广才岭成矿带钼矿床岩石地球化学特征及地球动力学研究

Lithogeochemical characteristics and geodynamics of the molybdenum deposits in Xiao Hinggan Mountains-Zhangguangcai range metallogenic belt

小兴安岭—张广才岭成矿带是国内重要的钼矿带,近年来陆续发现了多处储量巨大的钼矿床,本文在该区选取5个典型的斑岩型与矽卡岩型钼矿床进行矿床地质特征、成矿时代、岩石地球化学及反映的构造动力学环境研究与探讨。结果表明:5个钼矿床成矿岩石为过铝质-准铝质,属于高钾钙碱性系列岩石,整体表现出富集Rb、K、Th、U、Zr、Hf、Nd和明显亏损Nb、P、Ti、Ba、Sr等元素的特征,但矽卡岩型翠宏山、五道岭钼矿与斑岩型的鹿鸣、霍吉河与大黑山钼矿存在一定的差异,显示了不同成矿类型岩石特征的不一致性;成岩与成矿年龄多集中在168~187 Ma之间,为早-中侏罗世;花岗岩的Rb-Yb+Nb、Rb-Yb+Ta和R1-R2等构造环境判别图解均落入火山弧花岗岩与同碰撞花岗岩处,结合侏罗纪时期该区域上经历的构造岩浆活动特点,推测小兴安岭-张广才岭成矿带的钼矿成岩成矿与侏罗纪太平洋板块俯冲和佳木斯与松嫩地块的拼合有着密切的关系。

Xiao Hinggan Mountains-Zhangguangcai is an important molybdenum metallogenic belt in China.In recent years,several large molybdenum deposits have been discovered.Five typical porphyry type and skarn type molybdenum deposits were selected to study and discuss the geological characteristics,metallogenic epoch,geochemistry and the tectonic dynamics environment.The metallogenic rocks of 5 molybdenum deposits are peraluminum-quasi aluminum,belonging to a series of high potassium and calc-alkaline series rocks.The characteristics of the rock are the enrichment of Rb,K,Th,U,Zr,Hf,Nd elements and obvious losses of Nb,P,Ti,Ba and Sr.However,there are some differences between the skarn-type Cuihongshan,Wudaoling molybdenum deposit and Luming.Huojihe and Daheishan porphyry molybdenum deposits,the characteristics of rocks are different in metallogenic types.The ages of diagenesis and mineralization are mainly between 168-187Ma,which is early-middle Jurassic.The Rb-Yb+Nb,Rb-Yb+Ta and R1-R2 of granite are all located in the volcanic arc granite and collisional granite region.Combined with the tectonic magmatic activities experienced during,it is speculated that the mineralization and diagenesis of molybdenum ore is closely related to the subduction of Jurassic Pacific plate and the combination of Jiamusi and Songnen block.