Paleocene metamorphism along the Pennine–Austroalpine suture constrained by U–Pb dating of titanite and rutile (Malenco, Alps)

Swiss Journal of Geosciences

Table 1 Measured rutile and titanite U–Pb ages for the three studied samples from the Ur Breccia

Sample	Isochron age				Isochron type		Common Pb composition
Sample	Age (Ma)	± (95% conf.)	MSWD	n^a	Concordia type	Anchored isochron?	²⁰⁷Pb/²⁰⁶Pb_common	Source	Isochron slope^b
Titanite ages
19–85	38	16	0.3	7/7	Wetherill	Un-anchored	0.809 ± 0.037	Isochron slope	0.00897 ± 0.00039
28–20	57	5	1.2	20/20	Wetherill	Un-anchored	0.841 ± 0.023	Isochron slope	0.00863 ± 0.00023
60–65	48	11	1.8	10/10	Wetherill	Un-anchored	0.819 ± 0.026	Isochron slope	0.00886 ± 0.00027
Pooled (3 samples)	54.7	3.9	1.3	37/37	Wetherill	Un-anchored	0.833 ± 0.014	Isochron slope	0.008706 ± 0.00014
Rutile ages
19–85	63.0	2.7	1.3	19/20 [26]	Tera-Wasserburg	Anchored	0.839 ± 0.015^c	Stacey–Kramers 60 Ma
28–20	61	7	2.6	11/11 [23]	Tera-Wasserburg	Anchored	0.839 ± 0.015^c	Stacey–Kramers 60 Ma
Pooled (2 samples)	62.4	3.3	1.9	30/31 [49]	Tera-Wasserburg	Anchored	0.839 ± 0.015^c	Stacey–Kramers 60 Ma

^an indicates the number of analyses included in the calculation of the age, as a fraction of the total number of analyses. For rutile, only analyses for which ²⁰⁷Pb was distinguishable from background (> 50 cps) are included in this total; the total number of analyses including those with < 50 cps ²⁰⁷Pb is given in square brackets
^bThe measured slope of isochrons is given for un-anchored Wetherill concordia only; for these isochrons the ²⁰⁷Pb/²⁰⁶Pb_common was calculated from the isochron slope as described in text
^cFor anchored Tera-Wasserburg isochrons, the quoted ²⁰⁷Pb/²⁰⁶Pb_common is an assumed model common Pb composition (Stacey and Kramers 1975), and is not inferred from the isochron itself