Alteration of CAIs as recorded by ³⁶S/ ³⁴S as a function of ³⁵Cl/ ³⁴S
Publisher DOI
Abstract
Using new model calculations, we study the production of chlorine and sulfur isotopes in different irradiation scenarios. We demonstrate that irradiation during meteorite transit from the asteroid belt to Ear th has a negli gible influence on the sulfur isot opic composition. We analyzed five different physical assemblages: carbonaceous chondrites,
carbonaceous chondrites covered with water ice, carbonaceous chondrites covered with
water ice that contains silicates and chlorine, precursor CAIs, and water ice that contains
chlorine. For each of these five we ran simulations in which they were irradiated by galactic cosmic rays or solar energetic particles. We found that for producing sufficient amounts of ³⁶Cl, the required GCR and SEP flux densities must have been either unreasonably high on absolute terms or must had been high relatively late after the formation of the solar system. This finding casts doubt on the interpretation of the correlation lines in the diagram ³⁶S/ ³⁴S and ³⁵Cl/ ³⁴S as isochrons. Alternatively, the correlation may be interpreted as mixing between water that contains chlorine that has been irradiated (likely as ice) either by GCR or SEP particles and sulfur (without any chlori ne) with solar isotopic composition. Using this model we can explain the correlation as mixing between components, one of which was exposed to energetic particles; the conditions of this irradiation are not unrealistic
carbonaceous chondrites covered with water ice, carbonaceous chondrites covered with
water ice that contains silicates and chlorine, precursor CAIs, and water ice that contains
chlorine. For each of these five we ran simulations in which they were irradiated by galactic cosmic rays or solar energetic particles. We found that for producing sufficient amounts of ³⁶Cl, the required GCR and SEP flux densities must have been either unreasonably high on absolute terms or must had been high relatively late after the formation of the solar system. This finding casts doubt on the interpretation of the correlation lines in the diagram ³⁶S/ ³⁴S and ³⁵Cl/ ³⁴S as isochrons. Alternatively, the correlation may be interpreted as mixing between water that contains chlorine that has been irradiated (likely as ice) either by GCR or SEP particles and sulfur (without any chlori ne) with solar isotopic composition. Using this model we can explain the correlation as mixing between components, one of which was exposed to energetic particles; the conditions of this irradiation are not unrealistic
Date Issued
2018
Publication Type
Article
Subject(s)
Language(s)
en
Author(s)
Masarik, J. | |
Lin, Y. |
Additional Credits
Journal
Meteoritics & planetary science
Publisher
Meteoritical Society at the University of Arkansas, Dept. of Chemistry and Biochemistry
ISSN
1086-9379
Access(Rights)
restricted