松辽盆地徐家围子中生代火山岩形成环境

Formation Setting of the Mesozoic Volcanic Rocks in Xujiaweizi,Songliao Basin

岩石化学特征研究表明,研究区火山岩主要以中酸性岩石为主,基性岩石次之,主要呈中高钾的中—强钙碱性—弱碱性特征,少数为碱性和强碱性系列,火山岩共生组合特征显示该地区火山岩具有较弱的岩浆分异作用特征。通过利用主量元素特征来分析火山岩的形成环境可得:松辽盆地徐家围子断陷火山岩的形成构造环境主要为活动大陆边缘岩浆弧和(或)岛弧环境(太平洋区),少量火山岩形成于碱性或强碱性火山岩区(大西洋区)。

The research of Petrochemical characteristics indicated that the volcanic rocks in Xujiaweizi, Songliao Basin, are mainly the medium-acid rocks, the next is basic rocks, moreover, the rocks are mainly medium-high-K and the medium-strong calc-alkaline to weak alkaline, with a few of the alkaline and strong alkaline rocks. The volcanic rocks characteristics of symbiotic combination demonstrated that the volcanic rocks have the weak magmatic differentiation. Through the major elements characteristics is used to analyze the formation setting of volcanic rocks, the results show as follows： the formation setting of volcanic rocks of Xujiaweizi depression Xongliao basin mainly belongs to active continental margin magmatic arc and （or） island-arc environment （the Pacific Ocean area）,the few volcanic rocks form in the alkaline or strong alkaline volcanic zone （the Atlantic area）.