⁵³Mn-⁵³Cr Chronometry of CB chondrite: Evidence for uniform distribution of ⁵³Mn in the early solar system

High-precision Cr isotope ratios for chondrules and metal grain separated from CB chondrite Gujba were determined. The ε⁵⁴Cr values (εⁱCr = [(ⁱCr/⁵²Cr)sample/( ⁱCr/⁵²Cr)standard - 1] × 10⁴) for all samples were identical within the analytical uncertainty, with a mean value of +1.29 ± 0.02. Uniform ε⁵⁴Cr signatures of both chondrules and metal grains imply that the Cr isotope systematics of the meteorite was once completely equilibrated. The ε⁵³Cr values of the chondrules and metal grain, on the other hand, display a strong correlation with the ⁵⁵Mn/⁵²Cr ratio. The ⁵³Mn/⁵⁵Mn calculated from the slope of the isochron is (3.18 ± 0.52) × 10^-6. This corresponds to absolute ages of 4563.7 ± 1.2 Ma and 4563.5 ± 1.1 Ma using angrites D'Orbigny and LEW 86010, respectively, as time anchors. These ages are consistent with the ages obtained using other short- and long-lived radio nuclides, supporting the uniform distribution of ⁵³Mn in the early solar nebula.