新疆哈巴河县白哈巴村一带火山岩地质特征及构造意义

Geological Features of Volcanic Rock in Baihaba Village,Kaba,Xinjiang

该区火山岩分为南北两带,二者既有一定的成因联系,也有一定的个体差异。据岩石化学成果估算出南带火山岩岩浆房顶部的近似深度为3.97km,而北带火山岩岩浆房顶部的近似深度为1.65km。表明岩浆房是向南倾斜的。该区基底属过渡壳海盆基底性质,火山活动具有类双峰特征,但又不是陆内裂谷。岩石建造及微量、稀土、同位素等地球化学特征反映具有活动陆缘特征。流纹岩Sr初始比值87Sr0/86Sr0=0.711130±0.00083,据"不同成因类型花岗岩类的(87Sr/86Sr)年龄和岩浆源区的关系图解",投入下部壳源型区,表明岩浆可能主要来自下部地壳。

Volcanic rock in Baihaba Village,Kaba,Xinjiang is distributed over south and north zones.According to petrochemistry,magmatic chamber in the south zone was 3.97 km deep,while magmatic chamber in the north zone was 1.65 km deep.In other words,the magmatic chamber was inclined to the south.The basement was transitional crust in character.The volcanic activity was bimodal.Rock formation,minor element geochemistry,REE geochemistry and isotope geochemistry indicate an active continental margin.The initial Sr isotope ratio for rhyolite indicates lower crust-derived.