Radiogenic, nucleogenic and fissiogenic noble gas compositions in early Archaean magmatic zircons from Greenland

Abstract

We report a full suite of radiogenic, nucleogenic and fissiogenic noble gas compositions obtained by step-heating experiments from early Archaean Greenland zircons. We estimated activation energy (E a ) of diffusion and closure temperatures (T c ) for radiogenic 4 He* and fissiogenic 86 Kr* and 136 Xe* in zircons. These data demonstrate that the combined study of (U-Th)/He and (U-Th)/Kr-Xe can provide powerful geochronological information on cooling ages and crystallization ages from the same samples.

Noble gases in South Indian carbonatites: Trapped and in situ components

“…They may be applied to other U,Th rich minerals like monazite and zircon as well. In fact, this is also demonstrated from some recent studies of magmatic Archaean zircons from Greenland showing good retention of nucleogenic 21 Ne (Honda et al, 2004).…”

Crustal noble gases in deep brines as natural tracers of vertical transport processes in the Michigan Basin

“…Although release temperatures for Ne and Xe in these common minerals are currently uncertain, on the basis of their diffusivity decrease with increasing atomic numbers [ Ozima and Podosek , 2002], it is reasonable to assume that Ne release temperatures will fall between those of He and Ar (e.g., ∼70–250°C), while Xe release temperatures are expected to be greater than those of Ar (e.g., >275°C). These assumptions are supported by the increasing release temperatures for 4 He, 21 Ne, 84 Kr, and 136 Xe in zircons [ Honda et al , 2004; Gautheron et al , 2006], as well as the observed Xe release temperature in meteorites, which was shown to be greater than that of Ar [ Burkland et al , 1995]. Because of its currently low geothermal gradient (∼19°C/km) [ Vugrinovich , 1989], fluid temperatures in most of our sampled formations in the Michigan Basin are ∼40–80°C, far lower than release temperatures required for 40 Ar and 136 Xe.…”

Halogens and noble gases in Mathematician Ridge meta-gabbros, NE Pacific: implications for oceanic hydrothermal root zones and global volatile cycles

“…non-irradiated aliquots of three of the six samples using the VG 5400 noble gas mass spectrometer also at the ANU (Honda et al, 2004).…”

“…Analogous noble gas extraction procedures were used for isotopic analysis of He, Ne, Ar, Kr and Xe on the VG 5400 noble gas mass spectrometer. The differences were that the custom built air-actuated crushing devise accommodates larger samples (Matsumoto et al, 2001) (Honda et al, 2004).…”