Apatite Fission Track Thermochronology of Granite from Duobaoshan Porphyry Cu (Mo) Deposit, Northeast China: Implications for Cooling History and Ore Preservation

Table 2

Apatite fission track (AFT) results of samples from the Duobaoshan copper deposit.

Sample number	Nc	ρd(Nd) (×10^6 cm^-2)	ρs(Ns) (×10^5 cm^-2)	ρi(Ni) (×10^6 cm^-2)	U concentration (ppm)	P(χ^2) %	r	Pooled age (Ma ±1σ)	Mean track length (μm ±1σ)(Nj)	Dpar (μm)	Standard deviation (μm)
DB01	30	0.905(2261)	5.857(1233)	1.295(2727)	17.9	57.1	0.936	71.8 ± 3.5	13.76 ± 0.12(100)	1.58	1.28
DB37	30	0.878(2194)	2.826(578)	0.869(1777)	12.4	99.6	0.931	50.2 ± 3.0	13.80 ± 0.10(100)	1.60	1.00
DB66	30	0.871(2178)	2.212(365)	0.573(945)	8.2	100	0.963	59.1 ± 4.2	13.79 ± 0.11(100)	1.66	1.11
DB82	30	0.864(2161)	4.178(988)	1.119(2646)	16.2	86.2	0.890	56.7 ± 2.9	13.82 ± 0.10(100)	1.63	1.02
DB119	30	0.838(2094)	2.915(483)	0.808(1338)	12.0	93.2	0.900	53.2 ± 3.4	13.80 ± 0.10(100)	1.72	0.97
DB120	29	0.831(2077)	5.002(1189)	0.960(2281)	14.4	64.7	0.899	76.0 ± 3.8	13.67 ± 0.10(100)	1.53	1.07

Notes: Nc = number of apatite crystals analyzed. ρd = induced FT density calculated from muscovite external detectors used with SRM612 dosimeter. Nd = total number of FT counted in ρd. ρs = spontaneous FT density on the internal surfaces of apatite crystals analyzed. Ns = total number of FT counted in ρs. ρi = induced FT density on the muscovite external detector for crystals analyzed. Ni = total number of FT counted in ρi. P (χ²) = chi-squared probability that all single-crystal ages represent a single population of ages where degrees of freedom = Nc-1 [34]. r = correlation coefficient between Ns and Ni. Nj = number of horizontally confined FT lengths measured. Apatite-Zeta CN5 = 353.0 ±10.