Mantle, crustal and atmospheric noble gases in ailaoshan gold deposits, Yunnan Province, China

A two-component mantle source feeding Mt. Etna magmatism: Insights from the geochemistry of primitive magmas

“…It is unlikely that the SPA value is influenced by a post-eruptive accumulation of cosmogenic 3 He, because this sample has the highest He elemental concentration among those investigated and is, therefore, the least prone to isotope variation due to post-eruptive He accumulation. Furthermore, the single-step crushing procedure is known to minimize radiogenic-cosmogenic components (e.g., Burnard et al, 1999;Marty et al, 1994). No contribution of cosmogenic He was reported by Marty et al (1994) He values lower than 7.6 Ra measured in both historical (DEF and MONT) and prehistorical (FS, ET0901 and MAL) samples are probably not indicative of the mantle source, being influenced by secondary processes that occurred before or after the eruption.…”

He-Ar isotope geochemistry of the Yaoling-Meiziwo tungsten deposit, North Guangdong Province: Constraints on Yanshanian crust-mantle interaction and metallogenesis in SE China

“…ASW is characterized by atmospheric He and Ar isotope compositions (negligible isotope fractionation occurs during dissolution of noble gases), therefore 3 He/ 4 He= 1.39910 −6 = 1 Ra, 40 Ar/ 36 Ar = 295.5. Because noble gas solubility in low temperature aqueous fluid decreases with mass [1,10], the solubility of He in an aqueous setting is lowest, and the He abundance in air is very low. So, He is almost absent from ASW, e.g.…”

“…However, radiogenic 4 He, produced by the radioactive decay of U and Th in aquifer rocks, will diffuse into groundwater and hydrothermal fluids. So, most shallow groundwater or geological fluids of meteoric or marine origin have 3 He/ 4 He ratios that are lower than the atmospheric value but have atmospheric 40 Ar/ 36 Ar, which shows modified air-saturated water (MASW) characteristics [10,51].…”

“…As a result, in many metal deposits, mantle-derived He was discovered in ore fluids [1][2][3][4][5][7][8][9][10]12,[15][16][17][18][19][20][21][22][23][25][26][27][28][29]. Mantle He in crustal rocks is intimately related to crust-mantle interaction, and the formation and evolution of mantle magma.…”

Note: A dual temperature closed loop batch reactor for determining the partitioning of trace gases within CO2-water systems

“…These data can be used to determine locations of hydrocarbon reservoirs, 1,2 understanding natural analogues for Carbon Capture and Storage (CCS) projects, 3,4 constraining water recharge temperatures and rates in natural aquifers, 5,6 and indicating hydrothermal fluid origin and evolution within gold mineralisation zones. 7,8 The simplest way to experimentally derive partitioning for these tracers requires injecting a tracer-rich spike into closed system of interest, then collecting representative samples from both phases while the system is fully at equilibrium under specified P,T conditions. This requires a specially constructed experimental system.…”