Origin of nitrogen-rich natural gases in the California Great Valley: Evidence from helium, carbon and nitrogen isotope ratios

Geochemistry of fluid discharges from Peteroa volcano (Argentina-Chile) in 2010–2015: Insights into compositional changes related to the fluid source region(s)

“…do not allow to clearly discriminate between crustal and magmatic sources. Such a positive isotopic signature is indeed typical of 1) N 2 produced by thermal decomposition of organic material buried in sedimentary material (Jenden et al, 1988;Fischer et al, 2002;Snyder et al, 2003;Inguaggiato et al, 2004) likely involved in the subduction process, and/or 2) low-grade metamorphism affecting NH 4 fixed in the crystal lattices of K-rich minerals (micas and K-feldspars) of crystalline rocks (e.g., Honma and Itihara, 1981;Mingram and Brauer, 2001).…”

Hydrogen and carbon isotopic compositions of methane in N2- and CO2-rich gases from Central Japan.

“…The elevated N2/Ar ratios for the gas samples reflect probably the incorporation of nitrogen derived from organic matter in the crust (Matsuo et al, 1978;Jenden et al, 1988) The C02-rich gas samples contain more than 85% of carbon diox ide. Relatively low N2/Ar ratios ranging from 76 to 31 for the C02-rich gases suggest the contri bution of air dissolved in groundwaters (N2 / Ar 40) to the bubble gases.…”

“…Prior to this study, the Yuya(Gifu), Shikanoyu, Byakko, Yuya-2(Aichi) bubble gases were known to have 3He/4He ratios ranging from 3.0 x 10-6, about 2 times the at mospheric value (1.4 x 10-6), to 1.1 x 10-6 (Sano and Wakita, 1985). These high 3He/4He values and high helium concentrations of the gases in dicate the presence of a primordial 3He-rich com ponent derived from the mantle in addition to a crustal 4He-rich component in the gases (Craig et al, 1978;Poreda et al, 1986;Jenden et al, 1988). In both N2 and C02-rich gas samples, methane concentrations range from 23.4 to 0.8% and no C2 hydrocarbon gases have been detected.…”

Helium in the Australian liquefied natural gas economy

“…While Ballentine and Sherwood Lollar (2002) stated that gases with 4 He > 0.1% nearly always contain high nitrogen contents, the Australian natural gases generally show a weak positive correlation between 4 He and nitrogen and poor correlation within individual basins (Fig. 11), which does not support an overall strong correspondence between nitrogen and crustal, radiogenic helium nor the concept for a dominant deep metasedimentary or crystalline origin for the associated nitrogen (Jenden et al 1988a(Jenden et al , 1988b. Additionally, the stronger positive linear correlation between R/Ra and 3 He/N 2 (Fig.…”

“…The N 2 / 40 Ar air ratios for Australian natural gases range from around 1 to 3878, with the highest value in Dingo-3 gas, Amadeus Basin. Input of nitrogen from ASW and atmospheric sources would be expected to have values between~37 and 83, although values two to three times higher than this are commonly observed in hydrocarbon-and CO 2 -rich natural gases (Zartman et al 1961), while most volcanic sources extend N 2 / 40 Ar air ratios to 300 (Jenden et al 1988b). Approximately 86% of Australian natural gases have N 2 /…”