辽河盆地西部凹陷南区火山岩地球化学特征

GEOCHEMICAL CHARACTERITICS OF VOLCANIC ROCKS IN THE SOUTH OF WESTERN DEPRSSSION IN LIAOHE BASIN

辽河盆地西部凹陷南区的火山岩主要分布于中生界和下第三系，岩石类型多种多样。在岩石取心和岩石薄片不多的情况下，为了对本区火山岩准确定名，了解本区火山岩的地球化学特征以及岩浆的结晶分异等岩浆作用的形成和演化，对本区１２块火山岩的主元素分布（包括铬、钴、镍等微量元素分析）和７块火山岩的稀土元素进行了分析。本区中生界岩石类型主要为安山岩和碱流岩，而房身泡组主要是碱性玄武岩和玄武岩类，这表明在岩浆的演化过程中曾发生过橄榄石和辉石的结晶分异作用。本区火山岩应主要来自上地幔，而房身泡组源区相对较浅，可能有下地壳物质混人。

In the south of western depression in Liaohe basin, the volcanic rocks are distributed in Mesozoic group and Paleogene system. In order to actually name the volcanic rocks and to know about the geochemical characteristics of volcanic rocks, the genesis and evolution of magma and its crystallization differentiation etc., major elements (including the trace element of Cr, Co and Ni) of 12 samples and rare earth elements (REE) of 7 samples are tested. It is found that the volcanic rocks in Mesozoic group are andesite and pantellerite, and the volcanic rocks in Paloogene system are basalts, which shows that olivine and pyroxene had crystallized and differentiated during the evolution of magma. The volcanic rocks resulted from upper mantle in Mesozoic group, and volcanic rocks from lower crust in Palapene system.