N2 and CO2 in deep crustal fluids: evidence from the Caledonides of Norway

Andersen, Tom; Austrheim, Håkon; Burke, E. A. J.; Elvevold, Synnøve

doi:10.1016/0009-2541(93)90320-i

Cited by 99 publications

(54 citation statements)

References 36 publications

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“…For example, Andersen et al (1993) reported coexistence of CO 2 -N 2 fluid inclusions and H 2 O-rich fluid inclusions with about 30 wt. % NaCl equivalent in eclogites of the Norwegian Caledonides, which represent immiscible fluids at peak metamorphic conditions.…”

Section: Discussionmentioning

confidence: 99%

T1 - Immiscible C-H-O fluids formed at subduction zone conditions

Li¹

2016

Geochem. Persp. Let.

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Section: Discussionmentioning

confidence: 99%

T1 - Immiscible C-H-O fluids formed at subduction zone conditions

Li¹

2016

Geochem. Persp. Let.

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“…Pure CO 2 inclusions are commonly seen in lherzolite from mantle rocks (Roedder, 1984;Denies, 2002), and they are also typically found in high-grade metamorphic rocks such as granulites (Andersen et al, 1993;Touret, 2001). Carbonic fluid inclusion-dominated gold deposits have been studied in recent decades (Schmidt-Mumm et al, 1997;Xavier and Foster, 1999;Graupner et al, 2001;Wilde et al, 2001;Chi et al, 2006;Klein and Fuzikawa, 2010;Xu et al, 2015).…”

Section: The Origin Of Co 2 -Rich Fluids In the Sarekoubu-qiaxia Areamentioning

confidence: 97%

CO 2 -rich inclusions in vein gold–copper mineralization of the Sarekoubu–Qiaxia District, southern Altaides, China: Implication for ore genesis

Yang

Xing

et al. 2015

Journal of Geochemical Exploration

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“…However, even high pyrolysis temperatures in the laboratory are unable to eliminate isotopic fractionation during thermal disproportionation of N org from coal (e.g., Stiehl and Lehmann, 1980). (iii) Nitrogen isotope exchange between N org in source rocks and NH 4 + in aqueous fluids has been observed in hydrous pyrolysis experiments (Schimmelmann et al, 1998) + (e.g., Manning and Hutcheon, 2004) until metamorphism reaches stability fields where ammonium ions and ammonia are no longer stable in the free fluid phase (e.g., Hallam and Eugster, 1976;Andersen et al, 1993). The effect of isotopic buffering of δ 15 N org would extend into the temperature range of metamorphism if NH 3 or NH 4 + can penetrate into ultramicroporous carbonaceous grains.…”

Section: Mechanism For Organic Nitrogen Loss Without Isotope Fractionmentioning

confidence: 99%

Organic nitrogen chemistry during low-grade metamorphism

Boudou

Schimmelmann

Ader

et al. 2008

Geochimica et Cosmochimica Acta

135

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-Most of the organic nitrogen (N org ) on Earth is disseminated in crustal sediments and rocks in the form of fossil nitrogen-containing organic matter. The chemical speciation of fossil N org within the overall molecular structure of organic matter changes with time and heating during burial. Progressive thermal evolution of organic matter involves phases of enhanced elimination of N org and ultimately produces graphite containing only traces of nitrogen. Long-term chemical and thermal instability makes the chemical speciation of N org a valuable tracer to constrain the history of sub-surface metamorphism and to shed light on the subsurface biogeochemical nitrogen cycle and its participating organic and inorganic nitrogen pools. This study documents the evolutionary path of N org speciation, transformation and elimination before and during metamorphism and advocates the use of XRay Photoelectron Spectroscopy (XPS) to monitor changes in N org speciation as a diagnostic tool for organic metamorphism. Our multidisciplinary evidence from XPS, stable isotopes, traditional quantitative coal analyses, and other analytical approaches shows that at the metamorphic onset N org is dominantly present as pyrrolic and pyridinic nitrogen. The relative abundance of nitrogen substituting for carbon in condensed, partially aromatic systems (where N is covalently bonded to three C atoms) increases exponentially with increasing metamorphic grade, at the expense of pyridinic and pyrrolic nitrogen. At the same time, much N org is eliminated without significant nitrogen isotope fractionation. The apparent absence of Rayleigh-type nitrogen isotopic fractionation suggests that direct thermal loss of nitrogen from an organic matrix does not serve as a major pathway for N org elimination. Instead, we propose that hot H, O-containing fluids or some of their components gradually penetrate into the carbonaceous matrix and eliminate N org along a progressing reaction front, without causing nitrogen isotope fractionation in the residual N org in the unreacted core of the carbonaceous matrix. Before the reaction front can reach the core, an increasing part of core N org chemically stabilizes in the form of nitrogen atoms substituting for carbon in condensed, partially aromatic systems forming graphite-like structural domains with delocalized π-electron systems (nitrogen atoms substituting for "graphitic" carbon in natural metamorphic organic matter). Thus, this nitrogen species with a conservative isotopic composition is the dominant form of residual nitrogen at higher metamorphic grade.

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N2 and CO2 in deep crustal fluids: evidence from the Caledonides of Norway

Cited by 99 publications

References 36 publications

T1 - Immiscible C-H-O fluids formed at subduction zone conditions

T1 - Immiscible C-H-O fluids formed at subduction zone conditions

CO 2 -rich inclusions in vein gold–copper mineralization of the Sarekoubu–Qiaxia District, southern Altaides, China: Implication for ore genesis

Organic nitrogen chemistry during low-grade metamorphism

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