Cosmogenic isotope and track records in meteorites and their implications to cosmic ray fluxes

Abstract

Study of several cosmic ray effects, such as VH track density, spallogenic ²⁶Al and ⁵³Mn activity, ²¹Ne and ²²Ne/²¹Ne ratio, made in the same sample or in cores taken from different meteorites can identify parameters related to the exposure history of meteorites and cosmic ray flux variations. Meteorites with single or multiple exposure can be distinguished from a track production rate -²²Ne/²¹Ne correlation diagram and cosmic ray flux variations over 10⁶-10⁷ years can be deduced from a three-isotope correlation diagram of ²⁶Al, ⁵³Mn and ²¹Ne. Isotopic data based on chondrites with simple, one-stage exposure are consistent with the same average galactic cosmic ray intensity over the past 2 million years as that during the past 10⁷ years.