Study of Iron Cosmic Spherules from 1.8Ga and 1.6Ga Proterozoic Strata of the Ming Tombs District, Beijing

Key words: 
• Proterozoic era /
• cosmic spherules /
• Beijing Ming Tombs

Abstract: Numerous iron spherules have been found from coarse sandstone in the bottom of the Changzhougou Formation (1.8Ga) and silicified carbonate rock of the Dahongyu Formation (1.6Ga) of Proterozoic strata of the Ming Tombs District, Beijing. Most of them are round shaped as rod. Surface of iron cosmic spherules are observed by secondary back scanned image without carbon coating showing matallogenic graphs and “gas escape” holes so common during intro\|atmosphere melted and crystallized again. 44 testing points of 30 iron cosmic spherules have been measured by means of electron probe analysis average data as follows(%): FeO 8095; Cr2O3 0.786.56; NiO 0.060.41. Relatively, Cr2O3 is higher in spherules of the Changzhougou Formation but FeO higher in the Dahongyu Formation. However, the helium isotope analysis data are quite different between them. The abnormal of helium isotope made sure of extraterrestrial origin of iron cosmic spherules.