冀南武安岩体中闪长质杂岩体的成因矿物学研究

Genetic Mineralogical Study of Dioritic Complex in Wu'an Pluton,Southern Hebei Province

为了研究邯邢地区武安岩体中闪长质杂岩体的成因,利用电子探针微区分析和元素面扫描技术对其中的角闪石和斜长石的主量元素进行了分析,应用成因矿物学的方法计算了角闪石形成的物理化学条件,分析了斜长石的环带特征及其形成机制。研究发现,武安闪长质杂岩体中的角闪石多为镁角闪石,部分为阳起石。角闪石的矿物温压计计算结果显示,角闪石的形成温度为697℃~754℃,压力介于39 MPa^65 MPa之间,形成深度为1.5 km^2.4 km,氧逸度为ΔNNO+1.7^+2.4,平衡熔融体中的水含量为3.4%~4.3%。斜长石环带核部为中长石,幔部为更长石,边部为钠长石。研究认为,武安闪长质杂岩体是由地幔起源的基性岩浆与地壳起源的酸性岩浆通过岩浆混合作用形成。

In order to understand the genesis of dioritic complex in Wu'an pluton in Handan-Xingtai area,the major elements in the amphibole and plagioclase zoning of the Wu'an pluton were analyzed by electron microprobe analysis.The physico-chemical conditions for the formation of amphibole are calculated by the means of genetic mineralogy,and the zonal characteristics and formation mechanism of plagioclase are analyzed.We found that most of the amphibole in Wu'an diorite are magnesiohornblende,some are actinolite.amphibole thermobarometry shows that the amphibole phenocrysts were formed at 697~754℃and 39~65 MPa,corresponding to crustal depth of ca.1.5~2.4 km,with f O 2 ofΔNNO+1.7^+2.4 and magma water content of 3.4%~4.3%.The core of the plagioclase zoning is andesine,the mantle is oligoclase,and the edge is albite.It is believed that the Wu'an dioritic complex was formed by the mixing of mantle derived basic magma and crustal derived acidic magma.