辽宁永宁地区含金刚石闪长质岩石显微特征及金刚石来源探讨

辽宁永宁地区发育一套闪长质火山岩,该岩石中曾选获金刚石及其指示矿物,因此成为辽宁省金刚石第Ⅳ成矿带。通过对该岩石矿物组成及其显微结构构造特征研究,表明：(1)闪长质岩石中的斑晶斜长石具有环带结构;(2)橄榄石及金云母具有多世代性,且目估橄榄石+金云母含量在10%以上,局部更为富集;(3)出现“橄榄石+金云母+石榴石”与“斜长石+辉石+角闪石”不平衡的矿物组合;(4)发现橄榄石有碎斑结构和金伯利岩角砾。初步认为,永宁地区的闪长质岩浆在上升过程中捕获了早先已形成的金伯利岩并与之发生熔融混合作用,金刚石来自于深部的金伯利岩。这一认识对该地区寻找金刚石原生矿具有启示意义。

Microscopic characteristics of diamond-bearing dioritic rock in Yongning area, Liaoning province and discussion on source of the diamond

A set of dioritic volcanics occur in Yongning area, Liaoning province. Diamond and diamond-indicator minerals were picked out from the dioritic rock. Therefore, the dioritic rock belt becomes the diamond ore belt IV. Study on mineralogy, microscopic texture and structure of the rock shows that (1) plagioclase phenocrystal is characterized by ring structure, (2) olivine and phlogopite occur in many generations and visual estimation of olivine + phlogopite is >10% or more locally of total mineral constituent of the rock, (3) unbalanced mineral combination of olivine+phlogopite + garnet and plagioclase + pyroxene + hornblende occur in the rock, (4) clastic olivine phenocrystal and kimberlite breccia occur in the rock. It is believed that the ascending dioritic magma captured, melted and mixed the preexisting kimberlite. The diamond is derived from the deep kimberlite that will enlighten primary diamond prospecting in the area.