辽宁弓长岭太古宙斜长角闪岩中微球粒之发现

本文报道了辽宁弓长岭二矿区太古宙纹层状斜长角闪岩中微球粒之发现。微球粒一种呈暗色、不透明、有磁性;另一种为浅乳黄—棕黄色、透明—半透明、无磁性或弱磁性。它们多为玻璃质,强磁性者为磁铁矿。微球粒具气孔、瘤状、气泡塌陷、连体、凹坑等反映强塑性、高速运动、富挥发份、快速冷凝特征的多种表面和内部结构。其化学组成以SiO_2、TFe、Al_2O_3和CaO为主。它们的形成可能与火山作用或陨石撞击作用有关。无论其成因如何,均表明:1)纹层状斜长角闪岩的原岩为基性凝灰岩;2)本区变质温压条件存在微区不均匀性。

The Discovery of Microspherules in Archean Lamellar Plagioclase Amphibolite of Gongchangling Area,Liaoning Province

The microspherules reported here are discovered in lamellar plagioclaseamphibolite of the Gongchangling No. 2 Mine. The microspherules can be divi-ded into two kinds: one is black, opaque, and with magnetism; the other iscanary--citrine, transparent--semitransparent, and with weak or no magnetism.Most of them are glassy, but those with strong magnetism have become mag-netite. The microspherules have many kinds of surface and inher texturessuch as vesicle, tubercle, bubble breakdown and intergrowth, indieating thatthey were formed under such cotiditions as high temperature, abundance of vo-latile components, strong plasticity, and rapid movement and cooling. The micro-spherules are compositionally charadterized by high contents and wide varia-tion in SiO_2 (2.7%--55.9%), Al_2O_3(1.7%--23.9%), TFeO(2.1%--92.6%) andCaO(0.5%--33.5%) .Based on the present study, it is thought that their forma-tion might have been related either to volcanism or to meteorite impact. whi-chever origin the microspherules are of , the following important informationcan be drawn: (1) the original rocks of the lamellar plagioclase amphibolitesare basic tuffs formed by resedimentation; (2) metamorphic temperature-pressure conditions are somewhat inhomogenous in the study area.