摘要
This study covers cosmic spherules derived from the Mesoproterozoic Dahongyu Formation in the Ming Tombs area, Beijing. The cosmic spherules include iron oxide cosmic spherules, carbonaceous chondrites, and atomic iron "steely bead"-shaped cosmic spherules. The mineral assemblage of silicon carbide, forsterite, zircon, and glass spherules and fragments were picked from melt-silicified carbonate of the Mesoproterozoic Dahongyu Formation(ca. 1625 Ma). Cosmic spherule assemblages are solely discovered from sedimentary rocks in China. Platinum group elements(PGE) were determined for the first time in cosmic spherules and associated minerals. PGE comparative observation between meteorite and cosmic spherules is presented in this study. It is recognized that an extraterrestrial meteorite impact event might have occurred in the Dahongyu Stage. The main evidence is a large number of iron cosmic spherules in silicified oncolitic limestone, and associated cosmic silicon carbide, glass spherules, and fragments, as well as the presence of forsterite. The impact-volcanic crater is characteristic of a big black shale block dropped into the bended silicified limestone.
This study covers cosmic spherules derived from the Mesoproterozoic Dahongyu Formation in the Ming Tombs area, Beijing. The cosmic spherules include iron oxide cosmic spherules, carbonaceous chondrites, and atomic iron "steely bead"-shaped cosmic spherules. The mineral assemblage of silicon carbide, forsterite, zircon, and glass spherules and fragments were picked from melt-silicified carbonate of the Mesoproterozoic Dahongyu Formation(ca. 1625 Ma). Cosmic spherule assemblages are solely discovered from sedimentary rocks in China. Platinum group elements(PGE) were determined for the first time in cosmic spherules and associated minerals. PGE comparative observation between meteorite and cosmic spherules is presented in this study. It is recognized that an extraterrestrial meteorite impact event might have occurred in the Dahongyu Stage. The main evidence is a large number of iron cosmic spherules in silicified oncolitic limestone, and associated cosmic silicon carbide, glass spherules, and fragments, as well as the presence of forsterite. The impact-volcanic crater is characteristic of a big black shale block dropped into the bended silicified limestone.
基金
granted by National Nature Science Foundation of China(41472082,41402100,49772121,40172044,and 41173065)
Institute of Geology,Chinese Academy of Geological Sciences,ChinaGeological Survey(DD20190448 and DD20190370).
作者简介
first author:SONG Tianrui,male,born in 1931 in Taiyuan City,Shanxi Province,bachelor,graduated from Peking University,research fellow and doctoral supervisor of Institute of Geology,Chinese Academy of Geological Sciences.He is now interested in the study on mineralogy,petrology,and sedimentology.Email:songtianrui@cags.ac.cn,phone:010-68999695,13071159485;corresponding author:ZHENG Ning,female,born in 1983 in Panjin City,Liaoning Province,doctor,graduated from Chinese Academy of Geological Sciences,research assistant at the Institute of Geology,Chinese Academy of Geological Sciences.She is now interested in the study on sedimentology.Email:zhengninglaio@163.com,phone:010-68999726,15210019969.
