COSMIC DUST IN SUZHOU A-TYPE GRANITE

A large number of microspherules have been extracted from Suzhou A-typ e granite by means of heavy placer. Both natural surfaces and part sec tions of 539 microspherules have been observed by SEM. 457 microspheru les have been determined by EDX, with some of them by EPMA, XRD and IN AA. The results suggest these spherules are of ablated cosmic dust. Am ong them silicate glassy microspherules have been highly enriched in R EE and other lithophile refractory trace elements, and REE abundance p attern favors a meteoritic origin as a roughly flat distribution. Ring woodite has been first found in these glassy microspherules. The compo sition of these iron spherules is similar to those of the ablated cosm ic dust from deep sea nd polar ice. Some Fe-Ni spherules and spherules composed of troilite have also been found. This is probably the first report on various types of cosmic dust extracted from granite.