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Presence of 60Fe in eucrite Piplia Kalan: A new perspective to the initial 60Fe/ 56Fe in the early solar system

DRS at CSIR-National Institute of Oceanography

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Title Presence of 60Fe in eucrite Piplia Kalan: A new perspective to the initial 60Fe/ 56Fe in the early solar system
 
Creator Rudraswami, N.G.
Sahijpal, S.
Bhandari, N.
 
Subject eucrite
solar system
Cooling rate
ferrous pyroxenes
 
Description Fe-Ni isotope measurements of ferrous pyroxenes of the Piplia Kalan eucrite using Secondary Ion Mass Spectrometer revealed the presence of sup (60) Ni excess corresponding to the initial 60Fe/56Fe of (5.2 + or - 2.4) × 10 sup(-9). Combining this ratio with the inferred initial sup(26) Al/ sup(27) Al ratio of (7.5 + or - 0.9) × 10 sup(-7) in plagioclase of the Piplia Kalan that has been already reported in the literature suggests initial sup(60) Fe/ sup(56) Fe of (5.2 + or - 2.4) × 10 sup(-8) in the early solar system, which is significantly lower than the value inferred from Fe-Ni isotope measurements of chondrules in silicates and sulphides from unequilibrated ordinary chondrites. We attribute the difference in the initial sup(60)Fe/ sup(56) Fe to be solely due to the closure temperature of Fe-Ni isotope systematics, which is less compared to Al-Mg isotope systematics. With the initial sup(60) Fe/ sup(56) Fe values found in the Piplia Kalan, it is possible that the Fe-Ni isotope systematics was disturbed for another approx. 5 Ma (million years) after closure of the Al-Mg isotope systematics. The closure temperature of approx. 450-650 degrees C for Fe-Ni isotope system seems feasible and we anticipate a cooling rate of approx. 20-60 degrees C/Ma in the crust region of the parent body of Piplia Kalan, thereby matching the initial sup(60) Fe/sup(56) Fe to approx. 5 × 10 sup(-7). This is consistent with the initial value found in the silicate phases in chondrules of least metamorphosed meteorites. However, the presence of sup(60) Ni excess in Piplia Kalan does not confirm sup(60) Fe to be a major heat source for the early thermal evolution of meteorite parent bodies. Also, it seems that a massive star probably has contributed the two short-lived nuclides, sup(26) Al and sup(60) Fe, to the early solar system.
 
Date 2010-10-21T09:47:42Z
2010-10-21T09:47:42Z
2010
 
Type Journal Article
 
Identifier Current Science, vol.99(7); 948-952
http://drs.nio.org/drs/handle/2264/3729
 
Language en
 
Rights Copyright [2010]. All efforts have been made to respect the copyright to the best of our
knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.
 
Publisher Current Science Association