Nitrogen isotope fractionations during progressive metamorphism: A case study from the Paleozoic Cooma metasedimentary complex, southeastern Australia

Jia, Yiefei

doi:10.1016/j.gca.2006.08.004

Cited by 79 publications

(35 citation statements)

References 62 publications

(136 reference statements)

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“…It is noted that Brauer and Hahne (2005) reported that nitrogen content and N-isotope composition of rocks analyzed by an elemental analyzer coupled with an isotope mass spectrometer, like the one employed in this study, are sometimes lower than those derived from the conventional dissolution and distillation method (Haendel et al, 1986). On the other hand, Jia (2006) reported comparable N-isotope compositions of mica from both methods. Further studies may be necessary to evaluate the different methods.…”

Section: Methodsmentioning

confidence: 57%

“…In recent studies of progressive metamorphism of sedimentary sequences of a given age in subduction (Bebout and Fogel, 1992) or collision (Mingram and Brauer, 2001) complexes, the maximum N-isotope shift from littlemetamorphosed protoliths to greenschist-and amphibolite-facies counterparts was in general ~1‰ and 2‰, respectively. In studying granitic contact aureoles (Jia, 2006;Bebout et al, 1999b), N-isotope shift in country rocks is also low (<1‰) in chlorite and biotite zone and may reach to 3-8‰ at the contact. Mica/K-feldspar decomposition may be the major mechanism to account for large N-isotope enrichment in high grade metamorphic rocks.…”

Section: Fig 6 Cross Sections Showing Variations Of N/al (Molar) Ramentioning

confidence: 99%

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Nitrogen and N-isotope variation during low-grade metamorphism of the Taiwan mountain belt

Yui

Kao

2009

Geochem. J.

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To investigate factors affecting the evolution of nitrogen system in rocks during progressive metamorphism, unmetamorphosed to greenschist-facies pelitic samples were collected from both pelitic and (pelitic members of) psammitic rock sequences along two transects of the Taiwan mountain belt. Among all samples, greenschist-facies metapelites from the Tananao metamorphic basement of this mountain belt exhibit the most variable and depleted nitrogen content and δ 15 N values. The observations are difficult to interpret and can only be accounted for by complicated tectonic/metamorphic history of the basement complex. On the other hand, irrespective of the different metamorphic grades, samples from the metamorphosed cover strata, which have been subjected to only one stage of metamorphism, show comparable nitrogen and N-isotope composition. The only exception is that greenschist-facies metapelites from the pelitic members of psammitic rock sequence (i.e., the G(Ps) group samples) of the cover strata are enriched in the 15 N isotope by at least 1‰. Taking Al content as a normalizing factor, averaged N/Al and LOI/Al show systematic decrease through progressive metamorphism. Given the non-homogeneous nature of the sedimentary protoliths, the comparable N-isotope composition among the unmetamorphosed to zeolite-facies (i.e., S-Z) group, prehnite-pumpellyite-facies (i.e., PP) group and greenschist-facies (i.e., G) group samples from pelitic rock sequences can be explained by rock devolatilization with limited nitrogen depletion (<10%). High δ 15 N composition of the G(Ps) group samples might be mainly due to more extensive nitrogen depletion (~25%). It is suggested that during metamorphism, the pelitic rock sequence may approximate a closed system, while thick psammitic rock sequence may behave more like an open system, facilitating nitrogen depletion and N-isotope fractionation even for thin pelitic members within a thick psammitic sequence. Lithology, in addition to other factors, therefore plays a role in controlling the evolution of the nitrogen system during low-grade metamorphism. The present study implies that element transport by dehydration fluid in subduction zones may largely take place along fluid channel ways.

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Section: Methodsmentioning

confidence: 57%

Section: Fig 6 Cross Sections Showing Variations Of N/al (Molar) Ramentioning

confidence: 99%

Nitrogen and N-isotope variation during low-grade metamorphism of the Taiwan mountain belt

Yui

Kao

2009

Geochem. J.

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“…Metamorphism can increase sedimentary nitrogen isotope ratios by preferential volatilization of isotopically light NH 3 or N 2 (Bauersachs et al, 2009;Bebout et al, 1999;Bebout and Fogel, 1992;Boyd and Phillippot, 1998;Haendel et al, 1986;Jia, 2006;Mingram and Bräuer, 2001;Palya et al, 2011). However, the overall effect is variable and not always expressed (Busigny et al, 2003;Plessen et al, 2010;Yui et al, 2009), which prohibits precise corrections.…”

Section: Preservation Of Nitrogen Isotopes In the Rock Recordmentioning

confidence: 99%

The evolution of Earth's biogeochemical nitrogen cycle

Stüeken

Kipp

Koehler

et al. 2016

Earth-Science Reviews

318

287

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Nitrogen is an essential nutrient for all life on Earth and it acts as a major control on biological productivity in the modern ocean. Accurate reconstructions of the evolution of life over the course of the last four billion years therefore demand a better understanding of nitrogen bioavailability and speciation through time. The biogeochemical nitrogen cycle has evidently been closely tied to the redox state of the ocean and atmosphere. Multiple lines of evidence indicate that the Earth"s surface has passed in a non-linear fashion from an anoxic state in the Hadean to an oxic state in the later Phanerozoic. It is therefore likely that the nitrogen cycle has changed markedly over time, with potentially severe implications for the productivity and evolution of the biosphere. Here we compile nitrogen isotope data from the literature and review our current understanding of the evolution of the nitrogen cycle, with particular emphasis on the Precambrian. Combined with recent work on redox conditions, trace metal availability, sulfur and iron cycling on the early Earth, we then use the nitrogen isotope record as a platform to test existing and new hypotheses about biogeochemical pathways that may have controlled nitrogen availability through time. Among other things, we conclude that (a) abiotic nitrogen sources were likely insufficient to sustain a large biosphere, thus favoring an early origin of biological N 2 fixation, (b) evidence of nitrate in the Neoarchean and Paleoproterozoic confirm current views of increasing surface oxygen levels at those times, (c) abundant ferrous iron and sulfide in the midPrecambrian ocean may have affected the speciation and size of the fixed nitrogen reservoir, and (d) nitrate availability alone was not a major driver of eukaryotic evolution.

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“…Anaerobic degradation of organic matter during early diagenesis retains the initial ␦ 15 N value or decreases ␦ 15 N only to a slight extent (less than 2‰) (Freudenthal et al, 2001;Möbius et al, 2010;Robinson et al, 2012). On the other hand, although thermal metamorphism can increase C/N ratios to hundreds and even thousands, ␦ 15 N values might only increase to a small extent, depending on metamorphic grade, with increases of ∼1-2‰ at greenschist facies and of ∼3-4‰ at amphibolite facies (Bebout and Fogel, 1992;Jia, 2006;Mingram and Bräuer, 2001). As the ␦ 15 N bulk values from our studied successions are unlikely to have been modified significantly by post-depositional thermal alteration because of high H/C ratio values having been measured at the nearby coeval Yanwutan-Lijiatuo section (Guo et al, 2007b), nitrogen isotopic shifts if any caused by thermal alteration should be expressed consistently through the section in such a limited stratigraphic interval.…”

Section: Evaluation Of Nitrogen Isotope Datamentioning

confidence: 99%

Marine redox variations and nitrogen cycle of the early Cambrian southern margin of the Yangtze Platform, South China: Evidence from nitrogen and organic carbon isotopes

Wang

Struck

Guo

et al. 2015

Precambrian Research

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Nitrogen isotope fractionations during progressive metamorphism: A case study from the Paleozoic Cooma metasedimentary complex, southeastern Australia

Cited by 79 publications

References 62 publications

Nitrogen and N-isotope variation during low-grade metamorphism of the Taiwan mountain belt

Nitrogen and N-isotope variation during low-grade metamorphism of the Taiwan mountain belt

The evolution of Earth's biogeochemical nitrogen cycle

Marine redox variations and nitrogen cycle of the early Cambrian southern margin of the Yangtze Platform, South China: Evidence from nitrogen and organic carbon isotopes

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