四川广元上寺二叠系—三叠系界线层内微球粒的发现与研究  

DISCOVERY AND STUDY OF MICROSPHERULES AT THE PERMIAN—TRIASSIC BOUNDARY OF THE SHANGSI SECTION,GUANGYUAN,SICHUAN

作　　者：高振刚[1] 徐道一[1] 张勤文[2] 孙亦因[3] 

机构地区：[1]国家地震局地质研究所 [2]中国地质科学院地质研究所 [3]中国科学院地质研究所

出　　处：《地质论评》1987年第3期203-211,301-302,共11页Geological Review

基　　金：国家自然科学基金委员会资助

摘　　要：在四川广元上寺剖面二叠系—三叠系的界线层内发现了大量微球粒,这些微球粒数目的峰值在层位上与铱异常、碳稳定同位素负异常大体是一致的,与生物大量绝灭也大体上是相当的。显示了与白垩系—第三系界线层内相类似的微球粒数目变化特征。某些铁质微球粒的结构表明,微球粒形成于高温熔体急速冷却的物理环境。有些微球粒的Cr/Fe与CI型陨石相近,有些与铁质宇宙尘的相近,而有些则与地球物质的相近。微球粒的来源是复杂的,现有来源于地内的,也有来源于地外的。此文主要是介绍四川广元上寺剖面二叠系—三叠系的界线层内所发现的微球粒及对其研究的初步结果。Abundant microspherules have been recently discovered in the Permian--Trias-sic boundary layer of the Shangsi section in Guangyuan, Sichuan. In terms of thestratigraphic position, the peak value of microspherules is largely coincident withthe changes in Ir anomaly and negative stable carbon isotope anomaly and massextinction, which shows a similar change pattern of the number of microspherewith that shown in the Cretaceous--Tertiary boundary layer. Surface textures ofsome ferrusinous microspherules indicate that the microspherules are formed by cooling of high-temperature melt. In some microspherules the Cr/Fe ratio isclose to that of CI-type chondrite and iron cosmic dust, while in others the ratiois to that of terrestrial material. It suggests that the origin of microspherules iscomplex: They are of both extraterrestrial and terrestrial origins.

关 键 词：上寺 三叠系 微球粒 二叠系 铁质 四川广元 图版 界线 第三系 

分 类 号：P53[天文地球—古生物学与地层学]