Radial Distribution of Spallogenic K, Ca, Ti, V and Mn Isotopes in Iron Meteorites

Abstract

Abstract Cosmic-ray-produced stable nuclides of Ca (mass number: 42, 43, 44 and 46), Ti (46, 47, 49 and 50), V (50), Cr (50, 53 and 54) and the long-lived nuclides, 40 K and 53 Mn were determined along the radial axes of the iron meteorites Grant and Treysa. Grant was extensively examined and the results compared with rare gas data. Although Treysa does not include enough samples to allow detailed analysis, the depth profile shows typical features for a small meteorite. The results were compared with calculated profiles of 40 K, 49 Ti and 53 Mn using thick bombardment data. The approximate pre-atmospheric radii of Grant and Treysa were determined to be 30 cm and 14 cm, respectively. The effect of space erosion was also estimated by comparing the data of 49 Ti and radioactive 53 Mn in Grant and Treysa with the calculated patterns. It is suggested that space erosion of both meteorites is small (≲ 0 . 8 Å /y ) during the cosmic-ray exposure of several hundred million years.