Noble gas constraints on degassing processes

On the degassing state and the chemical structure of the Earth's interior inferred from noble gas isotopes-Past and recent views

“…MORB glasses which show the 4 He concentration of more than 5 × 10 -6 cm 3 STP/g systematically show high 4 He/ 21 Ne*, where 21 Ne* indicates nucleogenic component, exceeding the estimated production ratio of 2.2 × 10 7 and these values are correlated each other (Honda and Patterson, 1999). In contrast, the 4 He/ 21 Ne* for OIB glasses do not exceed the production ratio even if some samples show 4 He concentrations close to 10 -5 cm 3 STP/ g. Although some attempts have been made to explain such a difference including gas loss effects (e.g., Honda and Patterson, 1999;Moreira and Sarda, 2000), the detailed mechanism is not yet well understood. Furthermore, we have noted that the thickness of glassy portions are less than a few mm in the case of Loihi samples (Kaneoka et al, 2002), which is much thinner than that of MORB glasses which is in the order of 10 mm.…”

186Os and 187Os enrichments and high-3He/4He sources in the Earth’s mantle: Evidence from Icelandic picrites

“…The Iceland plume system is ideal for this examination because of the well-established high 3 He/ 4 He and the near-solar Ne isotopic compositions in many Iceland lavas. These noble gas characteristics likely require a deep mantle source that is distinct from the convecting upper mantle source for MORB (Kurz et al, l982;l985;Graham et al, l998;Harrison et al, l999;Hilton et al, l999;Breddam et al, 2000;Dixon et al, 2000;Moreira and Sarda, 2000;Moreira et al, 2001;Stuart et al, 2003;Graham, 2005;Ballentine et al, 2005;Macpherson et al, 2005). In addition, there is evidence in some Icelandic lavas, from both noble gases and lithophile elements, for varying contributions from the upper mantle MORB source as well as from several ancient crustal and/or mafic components within the mantle (Hemond et al, l993;Hanan and Schilling, l997;Fitton et al, l997;Taylor et al, l997;Stecher et al, l999;Hanan et al, 2000;Breddam et al, 2000;Chauvel and Hemond, 2000;Kempton et al, 2000;Thirlwall et al, 2004;Macpherson et al, 2005;Thirlwall et al, 2006;Kokfelt et al, 2006).…”

Lessons Learned from Natural and Industrial Analogues for Storage of Carbon Dioxide in Deep Geological Formations

“…Magma can have significant fractions of crustal material, either carbonate or organic carbon from buried sediments. The origins of magma in subduction zones, back arc basins, and hot spots are more complex than at mid-ocean spreading centers, where an exclusive mantle source is assumed (Giggenbach et al, 1993;Kerrick and Caldeira, 1998;Marty and Jambon, 1987;Marty and Tostikhin, 1998;Minissale et al, 1997;Moreira and Sarda, 2000;Nishio et al, 1998;Sano and Marty, 1995;Sano and Williams, 1996;Trull et al, 1993).…”

“…When CO 2 exceeds 25% by volume in hydrocarbon reservoirs, isotopic analysis typically shows a significant mantle component (Pankina et al, 1978;Rigby and Smith, 1981;Clayton et al, 1990;Giggenbach et al, 1990Giggenbach et al, , 1993Cappa and Rice, 1995;Dai et al, 1995;Giggenbach, 1995;Xu et al, 1995Xu et al, , 1997Hao et al, 1996;Wycherley et al, 1999;Ballentine et al, 2000). For further discussion of noble gas and isotope systematics as mantle tracers refer to: Dunai and Baur (1995), Xu et al (1995), Ballentine et al (1996), Ballentine (1997), Kambio et al (1998), Kaneoka (1998), Osenbruch et al (1998, Pedroni et al (1999), Moreira and Sarda (2000), and Ozima and Igarashi (2000).…”