黑龙江科洛富钾火山岩中超镁铁岩包体和捕虏晶的矿物学研究

MINERALOGY OF ULTRAMAFIC INCLUSIONS AND XENOCRYSTS IN K-RICH VOLCANIC ROCKS FROM KELUO, HEILONGJIANG PROVINCE

本文研究了黑龙江科洛火山群超镁铁岩包体和捕虏晶矿物的光学、化学成分和稀土元素特征,计算了Ⅰ型包体的平衡结晶温度、压力值,用Ⅰ型包体矿物/寄主岩的稀土元素比值与矿物的稀土元素分配系数进行了对比。本区的Ⅰ型包体与其寄主岩有成因联系;上地幔经历过地幔交代;地温较高,属于大洋-大陆裂谷型地温,推测其从某一时期起存在着大陆地壳向大洋地壳的转化;其橄榄石和单斜辉石捕虏晶来自上地幔,与Ⅰ型包体同源,具有相同的成因。

The characteristics of optics, chemical compositions and rare earth elements of minerals in ultramafic inclusions and xenocrysts from Keluo volcanic group, Heilongjiang province are studied in this paper. The temperatures and pressures of equilibrium crystallization of minerals in inclusions of group Ⅰ are calculated. REE ratio of inclusion minerals of group Ⅰ / host of Keluo is compared with partition coefficients of minerals. The result of the studies in this paper suggests that, genetic relation exists between group Ⅰ inclusions in this area and their host rocks; the upper mantle in this area has undergone mantle metasomatism; the geotemperature of this area is high, and equal to ocean-continental rift geotemperature. Thus, it may be deduced that the crust of this area changed from continental crust to oceanic crust in a certain period; the xenocrysts of olivine and clinopyroxene are xenocrysts from upper mantale, have the same source and the same genesis with inclusions of group Ⅰ.