Table 2 Summary of isotope analysis for three CsMPs using SIMS and γ spectrometry.

Isotopic ratio	OTZ3 (1σ)	KOI2 (1σ)	OMR1 (1σ)	Natural abundance ratio	SRM610 (1σ)
²³⁵U/²³⁸U	0.029584 (0.004967)	0.029341 (0.003032)	n/d	0.00729	0.002388 (0.000001)
¹³⁴(Cs + Ba)/¹³⁷(Cs + Ba)	0.02488 (0.00219)	0.03184 (0.00107)	0.03167 (0.00037)	—	—
¹³⁴Cs/¹³⁷Cs(γ)	0.0131	0.0135	0.0132
¹³⁴Ba_radiogenic/¹³⁷Ba_radiogenic(γ)	0.515	0.517	0.520
¹³⁴Cs/¹³⁴Ba_radiogenic(γ)	0.190	0.190	0.191
¹³⁷Cs/¹³⁷Ba_radiogenic(γ)	7.47	7.46	7.47
¹³⁴(Cs + Ba_radiogenic)/¹³⁷(Cs + Ba_radiogenic) (γ)	0.0724	0.0742	0.0727
¹³⁵Cs/¹³⁷(Cs + Ba_radiogenic)	0.3929 (0.0089)	0.4007 (0.0050)	0.4011 (0.0020)	—	—
¹³⁵Cs/¹³³Cs	0.3901 (0.0121)	0.3685 (0.0062)	0.3777 (0.0025)	—	—
¹³⁷(Cs + Ba_radiogenic)/¹³³Cs	0.9941 (0.0543)	0.9199 (0.0246)	0.9417 (0.0102)	—	—
¹³⁴(Cs + Ba_radiogenic)/¹³⁸Ba	36.6 (3.7)	35.3 (5.9)	137.7 (21.7)	0.03371	0.03371 (0.00009)
¹³⁶Ba/¹³⁸Ba	0.1523 (0.0124)	0.1638 (0.0191)	0.4293 (0.0697)	0.1095	0.1097 (0.0002)
⁸⁷Rb/⁸⁵Rb	2.407 (0.014)	2.284 (0.017)	2.236 (0.120)	0.3856	0.3857 (0.00009)
⁹⁰Sr	n/d	n/d	n/d	—	—
⁴¹K/³⁹K	0.07217 (0.00001)	—	—	0.07216	0.07214 (0.00003)
⁴⁰K/³⁹K	0.000127 (0.000041)	—	—	0.000125	—
⁴³Ca/⁴⁴Ca	0.06465 (0.00115)	—	—	0.06472	0.06469 (0.000005)

A NIST standard, SRM610, which contains depleted U, was also analyzed as a reference. Ten scans were conducted for each analytical spot on the CsMPs, meaning that the sequence of ten analyses represents a depth profile of the variation in the isotopic ratios; thus, SIMS analyses provide the isotope signatures inside the CsMPs. The average values are given in the table with the standard deviation calculated for the ten analyses and the standard deviations are given in the parenthesis as 1σ. The isotopic ratios recalculated from the results of γ spectrometry are annotated as (γ). Conversion of radioactivity to isotopic ratio was conducted by decay-correcting to the time of SIMS analysis. n/d stands for not detected.

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